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Yang Y, Zheng S, Feng Y. Associations between vitamin C intake and serum uric acid in US adults: Findings from National Health and Nutrition Examination Survey 2011-2016. PLoS One 2023; 18:e0287352. [PMID: 37831704 PMCID: PMC10575504 DOI: 10.1371/journal.pone.0287352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 06/04/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUNDS Dietary factors has been found to influence serum uric acid (SUA) levels. We further explored the associations between dietary and supplemental vitamin C intake and SUA in a large population-based study. METHODS The cross-sectional study included 6308 participants (3146 males and 3162 females) aged ≥20 years from the National Health and Nutrition Examination Survey (NHANES) 2011-2016 in the United States. The dietary vitamin C was log-transformed for statistical analysis. Hyperuricemia was defined as SUA concentrations >420 umol/L in males or >360 umol/L in females. The associations of dietary vitamin C and supplemental vitamin C with SUA levels and hyperuricemia risk were evaluated using weighted linear regression models and weighted multivariate logistic regression models, and a subgroup analysis stratified by gender was also conducted. RESULTS In this large-scale database study, there was a negative association between dietary vitamin C (log transformed) and SUA levels in US adults (β = -7.27, 95% CI: -11.58, -2.97). The inverse relationship existed among males but not females (P for interaction = 0.02). There was inverse correlation between dietary vitamin C (log transformed) and hyperuricemia risk (OR = 0.68, 95% CI: 0.57, 0.81), especially in males compared to females determined through an interaction test (P = 0.04). There were no associations between supplemental vitamin C and SUA levels (β = 1.00 (95% CI: -4.44, 6.44) or hyperuricemia risk (OR = 0.98 (95% CI: 0.78, 1.24). High-dosage supplemental vitamin C (>300 mg) and hyperuricemia risk were not associated (OR = 1.04, 95% CI: 0.69, 1.56). CONCLUSIONS This study demonstrated that there were negative associations between dietary vitamin C and SUA levels and hyperuricemia risk among US adults. The inverse correlations between dietary vitamin C and hyperuricemia risk were more significant in males compared to females. There were no associations between supplemental vitamin C and SUA levels or hyperuricemia risk.
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Affiliation(s)
- Yanting Yang
- Department of Gastroenterology, The Third People’s Hospital of Kunshan, Kunshan, China
| | - Sijie Zheng
- Endoscopy Center, The First People’s Hospital of Kunshan, Kunshan, China
| | - Yunfu Feng
- Endoscopy Center, The First People’s Hospital of Kunshan, Kunshan, China
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Cheng S, Shan L, You Z, Xia Y, Zhao Y, Zhang H, Zhao Z. Dietary patterns, uric acid levels, and hyperuricemia: a systematic review and meta-analysis. Food Funct 2023; 14:7853-7868. [PMID: 37599588 DOI: 10.1039/d3fo02004e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Abstract
Background: Studies investigating the effects of dietary intake on serum uric acid (SUA) and hyperuricemia have yielded inconsistent results. Therefore, we conducted a meta-analysis to assess the associations between various dietary patterns and SUA levels as well as hyperuricemia. Methods: We searched PubMed, Web of Science, and EMBASE databases for relevant articles examining the association between dietary intake and SUA levels and/or hyperuricemia published until March 2023. Dietary intake patterns were classified into plant-based, animal-based, and mixed dietary patterns based on predominant foods. The pooled effect sizes of eligible studies and their corresponding 95% confidence intervals (CIs) were estimated using random-effects models. Publication bias was assessed using Egger's test. Results: We included 41 studies, comprising 359 317 participants, that investigated the effects of dietary patterns on SUA levels (n = 25) and hyperuricemia (n = 19). Our findings suggested that a plant-based dietary pattern was associated with decreased SUA levels in both interventional (standard mean difference: -0.24 mg dL-1, 95% CI: -0.42, -0.06; I2 = 61.4%) and observational studies (odds ratio (OR): 0.92, 95% CI: 0.89, 0.95, I2 = 91.1%); this association was stronger in men (OR: 0.45, 95% CI: 0.35, 0.58; I2 = 0). We observed that plant- and animal-based dietary patterns were associated with a reduced risk (OR: 0.75; 95% CI: 0.67, 0.83, I2 = 93.3%) and an increased risk (OR: 1.38; 95% CI: 1.20, 1.59, I2 = 88.4%) of hyperuricemia, respectively. Conclusions: Collectively, a plant-based dietary pattern is negatively associated with SUA levels and hyperuricemia. Therefore, a plant-based dietary pattern should be recommended for the management of SUA levels and the prevention of hyperuricemia.
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Affiliation(s)
- Sijie Cheng
- Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
| | - Lishen Shan
- Department of Pediatrics, Shengjing Hospital of China Medical University, China
| | - Zhuying You
- Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
| | - Yang Xia
- Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
| | - Yuhong Zhao
- Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
- Clinical Research Center, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
- Liaoning Key Laboratory of Precision Medical Research on Major Chronic Disease, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China
| | - Hehua Zhang
- Clinical Research Center, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
- Liaoning Key Laboratory of Precision Medical Research on Major Chronic Disease, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China
| | - Zhiying Zhao
- Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Shenyang, Liaoning, 110004, China.
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Lin Z, Chen H, Lan Q, Chen Y, Liao W, Guo X. Composite Dietary Antioxidant Index Is Negatively Associated with Hyperuricemia in US Adults: An Analysis of NHANES 2007-2018. Int J Endocrinol 2023; 2023:6680229. [PMID: 37636314 PMCID: PMC10449592 DOI: 10.1155/2023/6680229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/29/2023] Open
Abstract
Hyperuricemia and its complications are severe risks to human health. Dietary intervention is considered an essential part of the management of hyperuricemia. Studies have reported that the intake of antioxidants has a positive effect on hyperuricemia. Here, we collected data from 8761 participants of the National Health and Nutrition Examination Survey for this analysis. Daily intakes of vitamins A, C, and E; manganese; selenium; and zinc were calculated as the composite dietary antioxidant index (CDAI). The participants were divided into four groups (Q1, Q2, Q3, and Q4) according to the CDAI. Univariate analysis was used to assess the association of covariates with hyperuricemia. The association between the CDAI and hyperuricemia was evaluated using multinomial logistic regression, and its stability was determined by stratified analysis. Our results revealed that the CDAI has a significant negative association with hyperuricemia (Q2: 0.81 (0.69, 0.95); Q3: 0.75 (0.62, 0.90); Q4: 0.65 (0.51, 0.82); P < 0.01). The results of stratified analysis emphasize that this association between CDAI and hyperuricemia is stable. In conclusion, this study suggested a negative association between the CDAI and hyperuricemia.
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Affiliation(s)
- Zhenzong Lin
- Department of Clinical Laboratory Medicine, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China
- Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Haokai Chen
- Department of Clinical Laboratory Medicine, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China
- Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Qiwen Lan
- Department of Medical Imageology, The Second Clinical School of Guangzhou Medical University, Guangzhou 511436, China
| | - Yinghan Chen
- Department of Medical Imageology, The Second Clinical School of Guangzhou Medical University, Guangzhou 511436, China
| | - Wanzhe Liao
- Department of Clinical Medicine, The Nanshan College of Guangzhou Medical University, Guangzhou 511436, China
| | - Xuguang Guo
- Department of Clinical Laboratory Medicine, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China
- Department of Clinical Medicine, The Third Clinical School of Guangzhou Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, China
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Hmong microbiome ANd Gout, Obesity, Vitamin C (HMANGO-C): A phase II clinical study protocol. PLoS One 2023; 18:e0279830. [PMID: 36724193 PMCID: PMC9891498 DOI: 10.1371/journal.pone.0279830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 11/29/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Hmong men in Minnesota exhibit a high prevalence of gout and hyperuricemia. Although evidence of vitamin C's effectiveness as a treatment for gout is mixed, analysis of therapeutic benefit based on an individual's multiomic signature may identify predictive markers of treatment success. OBJECTIVES The primary objective of the Hmong Microbiome ANd Gout, Obesity, Vitamin C (HMANGO-C) study was to assess the effectiveness of vitamin C on serum urate in Hmong adults with and without gout/hyperuricemia. The secondary objectives were to assess if 1) vitamin C impacts the taxonomic and functional patterns of microbiota; 2) taxonomic and functional patterns of microbiota impact vitamin C's urate-lowering effects; 3) genetic variations impact vitamin C's urate-lowering effects; 4) differential microbial biomarkers exist for patients with or without gout; and 5) there is an association between obesity, gut microbiota and gout/hyperuricemia. METHODS This prospective open-labelled clinical trial was guided by community-based participatory research principles and conducted under research safety restrictions for SARS-CoV-2. We aimed to enroll a convenient sample of 180 Hmong adults (120 with gout/hyperuricemia and 60 without gout/hyperuricemia) who provided medical, demographic, dietary and anthropometric information. Participants took vitamin C 500mg twice daily for 8 weeks and provided pre-and post- samples of blood and urine for urate measurements as well as stool samples for gut microbiome. Salivary DNA was also collected for genetic markers relevant to uric acid disposition. EXPECTED RESULTS We expected to quantify the impact of vitamin C on serum urate in Hmong adults with and without gout/hyperuricemia. The outcome will enhance our understanding of how gut microbiome and genomic variants impact the urate-lowering of vitamin C and associations between obesity, gut microbiota and gout/hyperuricemia. Ultimately, findings may improve our understanding of the causes and potential interventions that could be used to address health disparities in the prevalence and management of gout in this underserved population. TRIAL REGISTRATION ClinicalTrials.gov NCT04938024 (first posted: 06/24/2021).
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Yoshina S, Izuhara L, Kamatani N, Mitani S. Regulation of aging by balancing mitochondrial function and antioxidant levels. J Physiol Sci 2022; 72:28. [DOI: 10.1186/s12576-022-00853-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022]
Abstract
AbstractAging is the deterioration of physiological mechanisms that is associated with getting old. There is a link between aging and mitochondrial function. However, there is an unresolved relationship between ATP levels and aging. To address this issue, we administered febuxostat (FBX), an inhibitor of human xanthine oxidase (XO)/xanthine dehydrogenase (XDH), to C. elegans. We used C. elegans as a model to evaluate the effects of FBX and to challenge the enigma of the relationship between ATP and lifespan. In this study, we showed that FBX protects mitochondria and prevents age-related muscle deterioration in C. elegans. In addition, we showed that FBX administration could increase ATP levels without overloading the mitochondria while extending the lifespan. We also showed that the combination of FBX and an antioxidant as a protection against ROS prolongs lifespan more. We have shown that the antioxidant effects and increased ATP levels may lead to antiaging effects.
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Juraschek SP, Gaziano JM, Glynn RJ, Gomelskaya N, Bubes VY, Buring JE, Shmerling RH, Sesso HD. Effects of vitamin C supplementation on gout risk: results from the Physicians' Health Study II trial. Am J Clin Nutr 2022; 116:812-819. [PMID: 35575611 PMCID: PMC9437983 DOI: 10.1093/ajcn/nqac140] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/28/2022] [Accepted: 05/11/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Short-term randomized trials suggest that a 500 mg/d vitamin C supplement reduces serum urate, whereas observational studies show vitamin E is inversely associated with gout risk. OBJECTIVES We evaluated the effect of supplemental vitamin C (prespecified primary exposure) and vitamin E (prespecified secondary exposure) on new diagnoses of gout. METHODS We performed a post hoc analysis of data from the Physicians' Health Study II, a randomized, double-blind, placebo-controlled factorial trial of randomized vitamin C (500 mg/d) and vitamin E (400 IU every other day). The primary outcome was new gout diagnoses, self-reported at baseline and throughout the follow-up period of ≤10 y. RESULTS Of 14,641 randomly assigned male physicians in our analysis, the mean age was 64 ± 9 y; 1% were Black, and 6.5% had gout prior to randomization. The incidence rate of new gout diagnoses during follow-up was 8.0 per 1000 person-years among those assigned vitamin C compared with 9.1 per 1000 person-years among those assigned placebo. The vitamin C assignment reduced new gout diagnoses by 12% (HR: 0.88; 95% CI: 0.77, 0.99; P = 0.04). These effects were greatest among those with a BMI <25 kg/m 2 (P-interaction = 0.01). Vitamin E was not associated with new gout diagnoses (HR: 1.05; 95% CI: 0.92, 1.19; P = 0.48). CONCLUSIONS Vitamin C modestly reduced the risk of new gout diagnoses in middle-aged male physicians. Additional research is needed to determine the effects of higher doses of vitamin C supplementation on serum urate and gout flares in adults with established gout.The Physicians' Health Study II is registered at clinicaltrials.gov (identifier: NCT00270647).
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Affiliation(s)
- Stephen P Juraschek
- Division of General Medicine, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - J Michael Gaziano
- Division of Aging, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.,Massachusetts Veterans Epidemiology Research and Information Center (MAVERIC), VA Boston Healthcare System, Boston, MA, USA
| | - Robert J Glynn
- Division of Preventive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.,Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Natalya Gomelskaya
- Division of Preventive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Vadim Y Bubes
- Division of Preventive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Julie E Buring
- Division of Preventive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.,Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Robert H Shmerling
- Division of Rheumatology and Clinical Immunology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Howard D Sesso
- Division of Aging, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.,Division of Preventive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.,Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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7
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Gout and Diet: A Comprehensive Review of Mechanisms and Management. Nutrients 2022; 14:nu14173525. [PMID: 36079783 PMCID: PMC9459802 DOI: 10.3390/nu14173525] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 11/25/2022] Open
Abstract
Gout is well known as an inflammatory rheumatic disease presenting with arthritis and abnormal metabolism of uric acid. The recognition of diet-induced systemic metabolic pathways have provided new mechanistic insights and potential interventions on gout progression. However, the dietary recommendations for gouty patients generally focus on food categories, with few simultaneous considerations of nutritional factors and systemic metabolism. It is worthwhile to comprehensively review the mechanistic findings and potential interventions of diet-related nutrients against the development of gout, including purine metabolism, urate deposition, and gouty inflammation. Although piecemeal modifications of various nutrients often provide incomplete dietary recommendations, understanding the role of nutritional factors in gouty development can help patients choose their healthy diet based on personal preference and disease course. The combination of dietary management and medication may potentially achieve enhanced treatment effects, especially for severe patients. Therefore, the role of dietary and nutritional factors in the development of gout is systematically reviewed to propose dietary modification strategies for gout management by: (1) reducing nutritional risk factors against metabolic syndrome; (2) supplementing with beneficial nutrients to affect uric acid metabolism and gouty inflammation; and (3) considering nutritional modification combined with medication supplementation to decrease the frequency of gout flares.
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Nie J, Deng MG, Wang K, Liu F, Xu H, Feng Q, Li X, Yang Y, Zhang R, Wang S. Higher HEI-2015 scores are associated with lower risk of gout and hyperuricemia: Results from the national health and nutrition examination survey 2007-2016. Front Nutr 2022; 9:921550. [PMID: 35990332 PMCID: PMC9381708 DOI: 10.3389/fnut.2022.921550] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 06/28/2022] [Indexed: 11/18/2022] Open
Abstract
Gout, the most prevalent inflammatory arthritis, is becoming increasingly prevalent in the United States and across the world, and it adversely impacts people’s quality of life and their health. Few studies have focused on the relationship between daily dietary quality and gout, so the topic requires further exploration. Data were derived from the National Health and Nutrition Examination Survey 2007–2016, and the inclusion criteria of the analytic sample were (1) adults, age ≥20 years, with complete information about HEI-2015, gout, and uric acid; (2) complete information of demographics, lifestyle (BMI, smoking, drinking), and disease history [hypertension, chronic kidney disease (CKD), diabetes]. The quality of the daily diet was reflected using the Healthy Eating Index 2015 (HEI-2015). The baseline features of different groups were examined using the Scott-Rao chi-square tests, and the association between the HEI-2015 score and the risk of gout/hyperuricemia (HUA) was investigated using weighted logistic regression models. The effects of different dietary components in the HEI-2015 on reducing the risk of gout/HUA were evaluated by weighted quantile sum (WQS) regression models. After adjusting for demographic characteristics, behavioral covariates, and disease history, higher HEI-2015 scores were associated with a significantly lower risk of gout (OR: 0.878, 95% CI: 0.876–0.880) and HUA (OR: 0.978, 95% CI: 0.976–0.979) in weighted logistic regression. Dairy, whole grains, plant proteins, and added sugar contributed greatly in HEI-2015 to reducing gout risk (weights of WQS index: 42, 17.18, 16.13, and 7.93%, respectively). Dairy, total fruits, greens and beans, and plant proteins contributed greatly in HEI-2015 to reducing HUA risk (weights of WQS index: 28.9, 17.13, 16.84, and 11.39%, respectively). As the result, adherence to the American Dietary Guidelines may assist to decrease the risk of gout/HUA in American adults, and greater emphasis should be placed on dairy products, whole grains, fruits, legumes, and added sugars.
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Affiliation(s)
- Jiaqi Nie
- School of Public Health, Wuhan University, Wuhan, China
| | | | - Kai Wang
- School of Public Health, Wuhan University, Wuhan, China
| | - Fang Liu
- School of Public Health, Wuhan University, Wuhan, China
| | - Haoling Xu
- School of Public Health, Wuhan University, Wuhan, China
| | - Qianqian Feng
- School of Public Health, Wuhan University, Wuhan, China
| | - Xiaosong Li
- School of Public Health, Wuhan University, Wuhan, China
| | - Yichi Yang
- School of Public Health, Wuhan University, Wuhan, China
| | - Ruyi Zhang
- School of Public Health, Wuhan University, Wuhan, China
| | - Suqing Wang
- School of Public Health, Wuhan University, Wuhan, China.,School of Nursing, Wuhan University, Wuhan, China.,Center for Chronic Disease Rehabilitation, School of Nursing, Wuhan University, Wuhan, China
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Andrés M, Sivera F, Buchbinder R, Pardo Pardo J, Carmona L. Dietary supplements for chronic gout. Cochrane Database Syst Rev 2021; 11:CD010156. [PMID: 34767649 PMCID: PMC8589461 DOI: 10.1002/14651858.cd010156.pub3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Dietary supplements are frequently used for the treatment of several medical conditions, both prescribed by physicians or self administered. However, evidence of benefit and safety of these supplements is usually limited or absent. OBJECTIVES To assess the efficacy and safety of dietary supplementation for people with chronic gout. SEARCH METHODS We updated the original search by searching CENTRAL, MEDLINE, Embase, CINAHL, and four trials registers (August 2020). We applied no date or language restrictions. We also handsearched the abstracts from the 2010 to 2019 American College of Rheumatology and European League against Rheumatism conferences, and checked the references of all included studies. SELECTION CRITERIA We considered all published randomised controlled trials (RCTs) or quasi-RCTs that compared dietary supplements with no supplements, placebo, another supplement, or pharmacological agents for adults with chronic gout for inclusion. Dietary supplements included, but were not limited to, amino acids, antioxidants, essential minerals, polyunsaturated fatty acids, prebiotic agents, probiotic agents, and vitamins. The major outcomes were acute gout flares, study withdrawal due to adverse events (AEs), serum uric acid (sUA) reduction, joint pain reduction, participant global assessment, total number of AEs, and tophus regression. DATA COLLECTION AND ANALYSIS We used standard methodological procedures expected by Cochrane. MAIN RESULTS Two previously included RCTs (160 participants) met our inclusion criteria; we did not identify any new trials for this update. As these two trials evaluated different diet supplements (enriched skim milk powder (SMP) and vitamin C) with different outcomes (gout flare prevention for enriched SMP, and sUA reduction for vitamin C), we reported the results separately. One trial (120 participants), at unclear risk of selection and detection bias, compared SMP enriched with glycomacropeptides (GMP) with un-enriched SMP, and with lactose, over three months. Participants were predominantly men, aged in their 50s, who had severe gout. The results for all major outcomes were imprecise, except for pain. None of the results were clinically significant. The frequency of acute gout attacks, measured as the number of flares per month, decreased in all three groups over the three-month study period. The effects of enriched SMP (SMP/GMP/G600) compared with the combined control groups (SMP and lactose powder) at three months in terms of mean number of gout flares per month were not clinically significant (mean (standard deviation (SD)) flares per month: 0.49 (1.52) in SMP/GMP/G60 group versus 0.70 (1.28) in the control groups; absolute risk difference: mean difference (MD) -0.21 flares per month, 95% confidence interval (CI) -0.76 to 0.34; low-quality evidence). The number of withdrawals due to adverse effects was similar between groups (7/40 in SMP/GMP/G600 group versus 11/80 in control groups; (risk ratio (RR) 1.27, 95% CI 0.53 to 3.03); there were 4% more withdrawals in the SMP/lactose groups (10% fewer to 18% more; low-quality evidence). Serum uric acid reduction was similar across groups (mean (SD) -0.025 (0.067) mmol/L in SMP/GMP/G60 group versus -0.010 (0.069) in control groups; MD -0.01, 95% CI -0.04 to 0.01; low-quality evidence). Pain from self-reported gout flares (measured on a 10-point Likert scale) improved slightly more in the GMP/G600 SMP group compared with controls (mean (SD) -1.97 (2.28) in SMP/GMP/G600 group versus -0.94 (2.25) in control groups; MD -1.03, 95% CI -1.89 to -0.17). This was an absolute reduction of 10% (95% CI 20% to 1% reduction; low-quality evidence), which may not be of clinical relevance. The risk of adverse events was similar between groups (19/40 in SMP/GMP/G600 group versus 39/80 in control groups; RR 0.97, 95% CI 0.66 to 1.45); the absolute risk difference was 1% fewer adverse events (1% fewer to 2% more), low-quality evidence). Gastrointestinal events such as nausea, flatulence and diarrhoea were the most commonly reported adverse effects. Data for participant global assessment were not available for analysis; the study did not report tophus regression. One trial (40 participants), at high risk of selection, performance, and detection bias, compared vitamin C alone with allopurinol, and with allopurinol plus vitamin C, in a three-arm study. We only included data from the vitamin C versus allopurinol comparison in this review. Participants were predominantly middle-aged men, and their severity of gout was representative of gout in general. Allopurinol reduced sUA levels more than vitamin C (MD 0.10 mmol/L, 95% CI 0.06 to 0.15), low-quality evidence. The study reported no adverse events; none of the participants withdrew due to adverse events. The study did not assess the rate of gout attacks, joint pain reduction, participant global assessment, or tophus regression. AUTHORS' CONCLUSIONS While dietary supplements may be widely used for gout, this review found no high-quality that supported or refuted the use of glycomacropeptide-enriched skim milk powder or vitamin C for adults with chronic gout.
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Affiliation(s)
- Mariano Andrés
- Sección de Reumatología, Hospital General Universitario de Alicante, Alicante, Spain
- Departamento de Medicina Clínica, Universidad Miguel Hernández, Elche, Spain
| | - Francisca Sivera
- Departamento de Medicina Clínica, Universidad Miguel Hernández, Elche, Spain
- Servicio de Reumatologia, Hospital de Elda, Elda (Alicante), Spain
| | - Rachelle Buchbinder
- Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University; Monash-Cabrini Department of Musculoskeletal Health and Clinical Epidemiology, Cabrini Health, Melbourne, Australia
| | - Jordi Pardo Pardo
- Ottawa Hospital Research Institute, The Ottawa Hospital - General Campus, Ottawa, Canada
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Nakagawa T, Kang DH. Fructose in the kidney: from physiology to pathology. Kidney Res Clin Pract 2021; 40:527-541. [PMID: 34781638 PMCID: PMC8685370 DOI: 10.23876/j.krcp.21.138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/13/2021] [Indexed: 11/30/2022] Open
Abstract
The Warburg effect is a unique property of cancer cells, in which glycolysis is activated instead of mitochondrial respiration despite oxygen availability. However, recent studies found that the Warburg effect also mediates non-cancer disorders, including kidney disease. Currently, diabetes or glucose has been postulated to mediate the Warburg effect in the kidney, but it is of importance that the Warburg effect can be induced under nondiabetic conditions. Fructose is endogenously produced in several organs, including the kidney, under both physiological and pathological conditions. In the kidney, fructose is predominantly metabolized in the proximal tubules; under normal physiologic conditions, fructose is utilized as a substrate for gluconeogenesis and contributes to maintain systemic glucose concentration under starvation conditions. However, when present in excess, fructose likely becomes deleterious, possibly due in part to excessive uric acid, which is a by-product of fructose metabolism. A potential mechanism is that uric acid suppresses aconitase in the Krebs cycle and therefore reduces mitochondrial oxidation. Consequently, fructose favors glycolysis over mitochondrial respiration, a process that is similar to the Warburg effect in cancer cells. Activation of glycolysis also links to several side pathways, including the pentose phosphate pathway, hexosamine pathway, and lipid synthesis, to provide biosynthetic precursors as fuel for renal inflammation and fibrosis. We now hypothesize that fructose could be the mediator for the Warburg effect in the kidney and a potential mechanism for chronic kidney disease.
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Affiliation(s)
| | - Duk-Hee Kang
- Division of Nephrology, Department of Internal Medicine, Ewha Medical Research Institute, Ewha Womans University College of Medicine, Seoul, Republic of Korea
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Chattaraj KG, Paul S. The miscibility and solubility of uric acid and vitamin C in the solution phase and their structural alignment in the solid-liquid interface. Phys Chem Chem Phys 2021; 23:15169-15182. [PMID: 34227626 DOI: 10.1039/d1cp01504d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The crystallization of uric acid (UA) in humans is correlated with unpropitious medical predicaments, including gout and kidney stone germination. Its comparatively low solubility in physiological solutions is a significant contributory factor to UA biomineralization. The inhibition of UA aggregation is investigated as a reasonable approach for reducing kidney and gout-related problems. Therefore, we examine the role of vitamin C (Vit-C), a water-soluble vitamin, in the aggregation of UA, and its potency in solubilizing UA has been confirmed experimentally. We notice that Vit-C encapsulates the aggregated UA. Moreover, it can dismantle the assemblies of UA. We have proffered comprehensive molecular mechanisms of the interplay between the aggregated UA and Vit-C. Vit-C molecules are interspersed in solution due to its non-aggregating nature. We perceive that, through hydrogen bonding and aromatic stacking interactions, Vit-C molecules interact with UA molecules. The determination of the Flory-Huggins interaction parameters suggests that the presence of Vit-C enhances the solubility of UA aggregates. In addition, UA molecules are conformed on a monolayer graphene sheet, where they are assembled to create a 2D self-assembly. Vit-C, however, encapsulates and disseminates itself within the aggregated UA molecules on the surface. Therefore, the molecular mechanisms of the impact of Vit-C on UA aggregation can provide relevant insights into drug design against chronic diseases.
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Affiliation(s)
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India.
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High-Dose Vitamin C: Preclinical Evidence for Tailoring Treatment in Cancer Patients. Cancers (Basel) 2021; 13:cancers13061428. [PMID: 33804775 PMCID: PMC8003833 DOI: 10.3390/cancers13061428] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/02/2021] [Accepted: 03/16/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary Vitamin C is an indispensable micronutrient in the human diet due to the multiple functions it carries out in the body. Reports of clinical studies have indicated that, when administered at high dosage by the intravenous route, vitamin C may exert beneficial antitumor effects in patients with advanced stage cancers, including those refractory to previous treatment with chemotherapy. The aim of this article is to provide an overview of the current scientific evidence concerning the different mechanisms of action by which high-dose vitamin C may kill tumor cells. A special focus will be given to those mechanisms that provide the rationale basis for tailoring vitamin C treatment according to specific molecular alterations present in the tumor and for the selection of the most appropriate companion drugs. Abstract High-dose vitamin C has been proposed as a potential therapeutic approach for patients with advanced tumors who failed previous treatment with chemotherapy. Due to vitamin C complex pharmacokinetics, only intravenous administration allows reaching sufficiently high plasma concentrations required for most of the antitumor effects observed in preclinical studies (>0.250 mM). Moreover, vitamin C entry into cells is tightly regulated by SVCT and GLUT transporters, and is cell type-dependent. Importantly, besides its well-recognized pro-oxidant effects, vitamin C modulates TET enzymes promoting DNA demethylation and acts as cofactor of HIF hydroxylases, whose activity is required for HIF-1α proteasomal degradation. Furthermore, at pharmacological concentrations lower than those required for its pro-oxidant activity (<1 mM), vitamin C in specific genetic contexts may alter the DNA damage response by increasing 5-hydroxymethylcytosine levels. These more recently described vitamin C mechanisms offer new treatment opportunities for tumors with specific molecular defects (e.g., HIF-1α over-expression or TET2, IDH1/2, and WT1 alterations). Moreover, vitamin C action at DNA levels may provide the rationale basis for combination therapies with PARP inhibitors and hypomethylating agents. This review outlines the pharmacokinetic and pharmacodynamic properties of vitamin C to be taken into account in designing clinical studies that evaluate its potential use as anticancer agent.
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Role of Vitamin C in Prophylaxis and Treatment of Gout-A Literature Review. Nutrients 2021; 13:nu13020701. [PMID: 33671646 PMCID: PMC7926958 DOI: 10.3390/nu13020701] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/28/2021] [Accepted: 02/18/2021] [Indexed: 12/14/2022] Open
Abstract
Gout, known as “the disease of the kings”, is the most frequent type of arthritis. It results from sustained hyperuricemia that leads to monosodium urate crystal deposition in joint structures and soft tissue. Environmental factors such as diet affect the incidence of gout; there is a known relationship between the occurrence of an acute attack of gout and the consumption of alcohol and meat; and a low purine diet is a widely recognized nonpharmacological method of supplementing the treatment and preventing recurrence of arthritis. This review aims to summarize the current knowledge about the role of vitamin C in prevention and treatment of gout. A PubMed/Medline database search on the role of vitamin C in purine metabolism was done. Reports from in vitro and animal studies seem to be promising and to allow explanation of the physiological relationship between vitamin C and uric acid. Most epidemiological studies indicate a significant correlation between high vitamin C intake and lower serum uric acid levels. Despite promising observations, there are few observational and interventional studies, and their results do not clearly define the benefits of a high daily intake of vitamin C in preventing the development and recurrence of gout.
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Spencer ES, Pitcher T, Veron G, Hannam T, MacAskill M, Anderson T, Dalrymple-Alford J, Carr AC. Positive Association of Ascorbate and Inverse Association of Urate with Cognitive Function in People with Parkinson's Disease. Antioxidants (Basel) 2020; 9:antiox9100906. [PMID: 32977491 PMCID: PMC7598173 DOI: 10.3390/antiox9100906] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/17/2020] [Accepted: 09/20/2020] [Indexed: 12/02/2022] Open
Abstract
Oxidative stress is thought to contribute to the aetiology of neurological disorders such as Parkinson’s disease. Ascorbate (vitamin C) is a potent antioxidant and is associated with neurological and cognitive function. In this study we assessed the ascorbate status of a cohort of people with Parkinson’s disease (n = 215), aged 50–90 years, compared with a cohort of age matched healthy controls (n = 48). The study sample’s cognitive status ranged from normal to mild cognitive impairment and dementia. There was no difference between the Parkinson’s disease and healthy control groups with respect to mean ascorbate status, however, a higher proportion of participants with Parkinson’s disease had hypovitaminosis C (i.e., <23 μmol/L) compared with healthy controls (20% vs. 8%, respectively). Within the Parkinson’s disease group, Montreal Cognitive Assessment (MoCA) scores correlated positively with ascorbate concentrations, with higher ascorbate status associated with better cognitive function (r = 0.14, p = 0.045). Participants with hypovitaminosis C had significantly lower MoCA scores relative to participants with ascorbate concentrations >23 µmol/L (p = 0.014). Ascorbate concentrations were significantly lower in the cognitively impaired subgroup compared with the normal cognition subgroup in the Parkinson’s disease cohort (p = 0.03). In contrast, urate showed an inverse correlation with cognitive function (r = −0.19, p = 0.007), with higher urate concentrations observed in the cognitively impaired subgroup compared with the normal cognition subgroup (p = 0.015). There was an inverse association between ascorbate status and urate concentrations (r = −0.15, p = 0.017). Plasma protein carbonyls, a measure of systemic oxidative stress, were not significantly different between the Parkinson’s disease cohort and healthy controls, and there was no association with cognitive function (r = 0.09, p = 0.19) or with ascorbate status (r = −0.05, p = 0.45). Overall, our study showed ascorbate status was positively associated with cognitive function in Parkinson’s disease, suggesting that longitudinal studies investigating the temporal sequence of cognitive decline and ascorbate status are warranted.
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Affiliation(s)
- Emma S. Spencer
- Nutrition in Medicine Research Group, Department of Pathology and Biomedical Science, University of Otago, Christchurch 8011, New Zealand;
| | - Toni Pitcher
- Department of Medicine, University of Otago, Christchurch 8011, New Zealand; (T.P.); (M.M.); (T.A.); (J.D.-A.)
- New Zealand Brain Research Institute, Christchurch 8011, New Zealand
| | - Gabriel Veron
- Centre for Postgraduate Nursing Studies, University of Otago, Christchurch 8011, New Zealand; (G.V.); (T.H.)
| | - Tracey Hannam
- Centre for Postgraduate Nursing Studies, University of Otago, Christchurch 8011, New Zealand; (G.V.); (T.H.)
| | - Michael MacAskill
- Department of Medicine, University of Otago, Christchurch 8011, New Zealand; (T.P.); (M.M.); (T.A.); (J.D.-A.)
- New Zealand Brain Research Institute, Christchurch 8011, New Zealand
| | - Tim Anderson
- Department of Medicine, University of Otago, Christchurch 8011, New Zealand; (T.P.); (M.M.); (T.A.); (J.D.-A.)
- New Zealand Brain Research Institute, Christchurch 8011, New Zealand
| | - John Dalrymple-Alford
- Department of Medicine, University of Otago, Christchurch 8011, New Zealand; (T.P.); (M.M.); (T.A.); (J.D.-A.)
- New Zealand Brain Research Institute, Christchurch 8011, New Zealand
- School of Psychology, Speech, and Hearing, University of Canterbury, Christchurch 8140, New Zealand
| | - Anitra C. Carr
- Nutrition in Medicine Research Group, Department of Pathology and Biomedical Science, University of Otago, Christchurch 8011, New Zealand;
- Correspondence: ; Tel.: +64-3364-0649
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Nakagawa T, Lanaspa MA, Johnson RJ. The effects of fruit consumption in patients with hyperuricaemia or gout. Rheumatology (Oxford) 2020; 58:1133-1141. [PMID: 31004140 DOI: 10.1093/rheumatology/kez128] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/06/2019] [Indexed: 01/05/2023] Open
Abstract
The consumption of fructose has gained increased attention as a potential cause of hyperuricaemia since fructose metabolism produces urate as a byproduct. In addition to sucrose and high fructose corn syrup, fresh fruits also contain fructose, suggesting that patients with hyperuricaemia or gout might also avoid fresh fruit. However, the effect of fruits is complex. Some studies reported that fruit intake was associated with gout flares while other studies showed that fruits rather lowered the risk for gout. Thus, fruits should not be simply viewed as a source of fructose. The complexity of fruits is accounted for by several nutrients existing in fruits. Vitamin C, epicatechin, flavonols, potassium and fibre are all nutrients in fruits, and these factors could modify fructose and urate effects. In this review, we discuss clinical studies evaluating the effect of fruit and fruit juice intake on hyperuricaemia and gout, and propose potential mechanisms for how fruit may influence urate levels.
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Affiliation(s)
- Takahiko Nakagawa
- Department of Nephrology, Rakuwakai Otowa Hospital, Kyoto, Japan.,Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Miguel A Lanaspa
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, USA
| | - Richard J Johnson
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, USA
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Roumeliotis S, Roumeliotis A, Dounousi E, Eleftheriadis T, Liakopoulos V. Dietary Antioxidant Supplements and Uric Acid in Chronic Kidney Disease: A Review. Nutrients 2019; 11:nu11081911. [PMID: 31443225 PMCID: PMC6723425 DOI: 10.3390/nu11081911] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 02/07/2023] Open
Abstract
Increased serum levels of uric acid have been associated with the onset and development of chronic kidney disease (CKD), cardiovascular disease, and mortality, through several molecular pathogenetic mechanisms, such as inflammation and oxidative stress. Oxidative stress is present even in the early stages of CKD, progresses parallelly with the deterioration of kidney function, and is even more exacerbated in end-stage renal disease patients undergoing maintenance hemodialysis. Although acting in the plasma as an antioxidant, once uric acid enters the intracellular environment; it behaves as a powerful pro-oxidant. Exogenous intake of antioxidants has been repeatedly shown to prevent inflammation, atherosclerosis and oxidative stress in CKD patients. Moreover, certain antioxidants have been proposed to exert uric acid-lowering properties. This review aims to present the available data regarding the effects of antioxidant supplements on both oxidative stress and uric acid serum levels, in a population particularly susceptible to oxidative damage such as CKD patients.
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Affiliation(s)
- Stefanos Roumeliotis
- Division of Nephrology and Hypertension, 1st Department of Internal Medicine, AHEPA Hospital, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | - Athanasios Roumeliotis
- Division of Nephrology and Hypertension, 1st Department of Internal Medicine, AHEPA Hospital, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece
| | - Evangelia Dounousi
- Department of Nephrology, School of Medicine, University of Ioannina, Ioannina 45110, Greece
| | | | - Vassilios Liakopoulos
- Division of Nephrology and Hypertension, 1st Department of Internal Medicine, AHEPA Hospital, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki 54636, Greece.
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Koguchi T, Tadokoro T. Beneficial Effect of Dietary Fiber on Hyperuricemia in Rats and Humans: A Review. INT J VITAM NUTR RES 2019; 89:89-108. [PMID: 30789803 DOI: 10.1024/0300-9831/a000548] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Hyperuricemia is recognized as a lifestyle-related disease and the prevalence is increasing in many parts of the world. Excessive intake of purines increases serum uric acid concentration and is thought to be one factor causative of hyperuricemia. Therefore, it is thought that prevention of hyperuricemia by dietary control may be very important. This is an article of our basic research regarding the role of dietary fiber in the suppression of hyperuricemia induced by dietary purines in rats; in addition, clinical research suggesting the possibility that dietary fiber intake has a beneficial effect on the prevention or suppression of hyperuricemia in humans is discussed. Our own studies reveal that the test dietary fiber significantly suppresses the elevation of serum uric acid concentration induced by dietary RNA (12.3-46.2%), adenosine-5'-monophosphate (9.5-23.2%), adenosine (10.7-20.4%), or adenine (16.3-38.9%) and suppresses experimental hyperuricemia in rats. The mechanism is presumed to be mediated by suppression of the digestion and/or absorption of dietary purines by dietary fiber. In clinical studies, intake of dietary fiber decreases serum uric acid concentrations. Reports of recent epidemiological studies indicate that higher levels of hyperuricemia increase the prevalence of its comorbidities (e.g., chronic kidney disease, obesity, hypertension, diabetes, and cardiovascular disease) and dietary fiber intake is associated with significantly lower risk for hyperuricemia and its comorbidities. We wish to emphasize the importance of recognizing the validity of increased dietary fiber intake as a preventive or suppressive method for hyperuricemia and its comorbidities.
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Affiliation(s)
- Takashi Koguchi
- 1Department of Human Education, Kokugakuin Tochigi Junior College, 608 Hirai-cho, Tochigi-Shi, Tochigi 328-8588, Japan
| | - Tadahiro Tadokoro
- 2Department of Administrative Nutrition, Faculty of Health and Nutrition, Tokyo Seiei College, 1-4-6, Nishishinkoiwa, Katsushika-ku, Tokyo 124-8530, Japan
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18
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Peng H, Feng D, Wang Y, Dong Z, Chen Q, Zhang L, Luo R, Chen J, Wang A, Ma S. Effect of Oral Vitamin C Supplementation on High-Altitude Hyperuricemia in Young Men Initially Migrating to High Altitude: A Pilot Study. High Alt Med Biol 2018; 19:373-381. [PMID: 30358417 DOI: 10.1089/ham.2018.0058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVE Clinical studies have shown that oral vitamin C supplementation can reduce serum uric acid levels in multiple populations and may also improve acute mountain sickness. However, it is unclear whether this protocol can improve high-altitude hyperuricemia. Therefore, we aimed to evaluate the role of vitamin C supplementation on high-altitude hyperuricemia. METHODS A preliminary prospective control study was performed in 2015. Young male army recruits (n = 66), who had recently arrived on the Tibetan Plateau for the first time, were recruited for study I. Subjects were assigned to either the vitamin C group, who took an oral daily dose of 500 mg vitamin C for 1 month, or the blank control group, who had no intervention. The levels of serum uric acid, serum creatinine, and blood urea nitrogen were monitored at baseline and at the end of 1 month. In a second study II in 2016 (n = 120), the effect of 500 mg/d vitamin C on high-altitude hyperuricemia was compared with 75 IU/d of vitamin E. RESULTS In study I, the level of serum uric acid at 1 month was significantly higher than at baseline (436.1 ± 79.3 μmol/L vs. 358.0 ± 79.8 μmol/L, p < 0.001) and the prevalence of hyperuricemia was also significantly higher (63.6% [95% confidence interval, CI: 52.0%-75.2%] vs. 19.7% [95% CI: 10.1%-29.3%], p < 0.001). Both the level of serum uric acid (411.5 ± 74.2 μmol/L vs. 460.8 ± 54.8 μmol/L, p = 0.003) and the prevalence of hyperuricemia (48.5% [95% CI: 31.4%-65.6%] vs. 78.8% [95% CI: 64.9%-92.7%], p = 0.020) were significantly lower in the vitamin C group than in the blank control group. In study II, the levels of serum uric acid and the frequency of hyperuricemia also increased over 1 month and were similar in the vitamin C and the vitamin E groups at both baseline and 1 month (p > 0.05). The change in serum uric acid was positively correlated with both the changes in serum creatinine (r = 0.599, p < 0.001) and blood urea nitrogen (r = 0.207, p = 0.005). CONCLUSIONS These findings indicate that healthy young men develop an increase in serum uric acid within a month of moving from low to high altitude. Oral vitamin C supplementation can safely reduce this increase at a low cost.
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Affiliation(s)
- Hui Peng
- 1 Department of Infectious Disease, Kunming General Hospital of Chengdu Military Command, Kunming, China.,2 Department of Postgraduate, Kunming Medical University, Kunming, China
| | - Dongfang Feng
- 3 Laboratory Department, Tibet Military Region General Hospital, Tibet, China
| | - Yingkai Wang
- 4 Medical Administration Division, Tibet Military Region General Hospital, Tibet, China
| | - Zixi Dong
- 5 Medical Administration Division, Kunming General Hospital of Chengdu Military Region, Kunming, China
| | - Qing Chen
- 1 Department of Infectious Disease, Kunming General Hospital of Chengdu Military Command, Kunming, China.,2 Department of Postgraduate, Kunming Medical University, Kunming, China
| | - Lihong Zhang
- 1 Department of Infectious Disease, Kunming General Hospital of Chengdu Military Command, Kunming, China
| | - Ruigang Luo
- 6 Medical Team, Tibet Military Region 77649 Unit, Tibet, China
| | - Jinsong Chen
- 6 Medical Team, Tibet Military Region 77649 Unit, Tibet, China
| | - Anjun Wang
- 6 Medical Team, Tibet Military Region 77649 Unit, Tibet, China
| | - Shiwu Ma
- 1 Department of Infectious Disease, Kunming General Hospital of Chengdu Military Command, Kunming, China.,7 State Key Laboratory of Organ Failure Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
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Gout. Integr Med (Encinitas) 2018. [DOI: 10.1016/b978-0-323-35868-2.00069-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Vitamin C supplementation and serum uric acid: A reaction to hyperuricemia and gout disease. PHARMANUTRITION 2017. [DOI: 10.1016/j.phanu.2017.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Caliceti C, Calabria D, Roda A, Cicero AFG. Fructose Intake, Serum Uric Acid, and Cardiometabolic Disorders: A Critical Review. Nutrients 2017; 9:nu9040395. [PMID: 28420204 PMCID: PMC5409734 DOI: 10.3390/nu9040395] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 02/07/2023] Open
Abstract
There is a direct relationship between fructose intake and serum levels of uric acid (UA), which is the final product of purine metabolism. Recent preclinical and clinical evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, and cardiovascular disease. It is probably also an independent risk factor for chronic kidney disease, Type 2 diabetes, and cognitive decline. These relationships have been observed for high serum UA levels (>5.5 mg/dL in women and >6 mg/dL in men), but also for normal to high serum UA levels (5-6 mg/dL). In this regard, blood UA levels are much higher in industrialized countries than in the rest of the world. Xanthine-oxidase inhibitors can reduce UA and seem to minimize its negative effects on vascular health. Other dietary and pathophysiological factors are also related to UA production. However, the role of fructose-derived UA in the pathogenesis of cardiometabolic disorders has not yet been fully clarified. Here, we critically review recent research on the biochemistry of UA production, the relationship between fructose intake and UA production, and how this relationship is linked to cardiometabolic disorders.
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Affiliation(s)
- Cristiana Caliceti
- Department of Chemistry "Giacomo Ciamician", Alma Mater Studiorum, University of Bologna, 40126 Bologna, Italy.
- Istituto Nazionale Biostrutture e Biosistemi (INBB), 00136 Rome, Italy.
- Centro Interdipartimentale di Ricerca Industriale Energia e Ambiente (CIRI EA), Alma Mater Studiorum, University of Bologna, 47900 Rimini, Italy.
| | - Donato Calabria
- Centro Interdipartimentale di Ricerca Industriale Energia e Ambiente (CIRI EA), Alma Mater Studiorum, University of Bologna, 47900 Rimini, Italy.
| | - Aldo Roda
- Department of Chemistry "Giacomo Ciamician", Alma Mater Studiorum, University of Bologna, 40126 Bologna, Italy.
- Istituto Nazionale Biostrutture e Biosistemi (INBB), 00136 Rome, Italy.
- Centro Interdipartimentale di Ricerca Industriale Energia e Ambiente (CIRI EA), Alma Mater Studiorum, University of Bologna, 47900 Rimini, Italy.
| | - Arrigo F G Cicero
- Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy.
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Kakutani-Hatayama M, Kadoya M, Okazaki H, Kurajoh M, Shoji T, Koyama H, Tsutsumi Z, Moriwaki Y, Namba M, Yamamoto T. Nonpharmacological Management of Gout and Hyperuricemia: Hints for Better Lifestyle. Am J Lifestyle Med 2015; 11:321-329. [PMID: 30202351 DOI: 10.1177/1559827615601973] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 07/06/2015] [Accepted: 07/13/2015] [Indexed: 12/22/2022] Open
Abstract
We reviewed lifestyle factors that influence serum uric acid levels and risk of gout flare, and how to improve their deleterious effects. Since obesity increases uric acid and weight gain increases gout risk, weight reduction by daily exercise and limiting intake of excess calories is recommended. However, strenuous exercise, which causes adenine nucleotide degradation; starvation, which decreases uric acid excretion; and dehydration may raise the level of uric acid in serum and trigger gout. Increased intake of purine-rich foods, such as meat and seafood, raise the level of uric acid in serum and is associated with increased risk of gout, whereas dairy products, especially low-fat types, are associated with a lower risk of gout. Also, heavy alcohol drinking raises the uric acid level and increases the risk of gout through adenine nucleotide degradation and lactate production. Sweet fruits and soft drinks containing fructose should be moderated, since fructose may raise uric acid and increase gout risk through uric acid production and/or decreased excretion. On the other hand, the Mediterranean diet is recommended for gout patients, since it may also help prevent hyperuricemia. Furthermore, coffee and vitamin C supplementation could be considered as preventive measures, as those can lower serum uric acid levels as well as the risk of gout.
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Affiliation(s)
- Miki Kakutani-Hatayama
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Manabu Kadoya
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Hirokazu Okazaki
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Masafumi Kurajoh
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Takuhito Shoji
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Hidenori Koyama
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Zenta Tsutsumi
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Yuji Moriwaki
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Mitsuyoshi Namba
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Tetsuya Yamamoto
- Division of Diabetes, Endocrinology, and Metabolism, Department of Internal Medicine, Hyogo College of Medicine, Hyogo, Japan
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Ekpenyong CE, Daniel N. Roles of diets and dietary factors in the pathogenesis, management and prevention of abnormal serum uric acid levels. PHARMANUTRITION 2015. [DOI: 10.1016/j.phanu.2014.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Bae J, Shin DH, Chun BY, Choi BY, Kim MK, Shin MH, Lee YH, Park PS, Kim SK. The effect of vitamin C intake on the risk of hyperuricemia and serum uric acid level in Korean Multi-Rural Communities Cohort. Joint Bone Spine 2014; 81:513-9. [DOI: 10.1016/j.jbspin.2014.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/22/2014] [Indexed: 12/20/2022]
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Abstract
BACKGROUND Dietary supplements are frequently used for the treatment of several medical conditions, both prescribed by physicians or self administered. However, evidence of benefit and safety of these supplements is usually limited or absent. OBJECTIVES To assess the efficacy and safety of dietary supplementation for people with chronic gout. SEARCH METHODS We performed a search in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and CINAHL on 6 June 2013. We applied no date or language restrictions. In addition, we performed a handsearch of the abstracts from the 2010 to 2013 American College of Rheumatology (ACR) and European League against Rheumatism (EULAR) conferences, checked the references of all included studies and trial registries. SELECTION CRITERIA We considered all published randomised controlled trials (RCTs) or quasi-RCTs that compared dietary supplements with no supplements, placebo, another supplement or pharmacological agents for adults with chronic gout for inclusion. Dietary supplements included, but were not limited to, amino acids, antioxidants, essential minerals, polyunsaturated fatty acids, prebiotic agents, probiotic agents and vitamins. The main outcomes were reduction in frequency of gouty attacks and trial participant withdrawal due to adverse events. We also considered pain reduction, health-related quality of life, serum uric acid (sUA) normalisation, function (i.e. activity limitation), tophus regression and the rate of serious adverse events. DATA COLLECTION AND ANALYSIS We used standard methodological procedures expected by The Cochrane Collaboration. MAIN RESULTS We identified two RCTs (160 participants) that fulfilled our inclusion criteria. As these two trials evaluated different diet supplements (enriched skim milk powder (SMP) and vitamin C) with different outcomes (gout flare prevention for enriched SMP and sUA reduction for vitamin C), we reported the results separately.One trial including 120 participants, at moderate risk of bias, compared SMP enriched with glycomacropeptides (GMP) with unenriched SMP and with lactose over three months. Participants were predominantly men aged in their 50's who had severe gout. The frequency of acute gout attacks, measured as the number of flares per month, decreased in all three groups over the study period.The effects of enriched SMP (SMP/GMP/G600) compared with the combined control groups (SMP and lactose powder) at three months in terms of mean number of gout flares per month were uncertain (mean ± standard deviation (SD) flares per month: 0.49 ± 1.52 in SMP/GMP/G60 group versus 0.70 ± 1.28 in control groups; mean difference (MD) -0.21, 95% confidence interval (CI) -0.76 to 0.34; low-quality evidence). The number of withdrawals due to adverse effects was similar in both groups although again the results were imprecise (7/40 in SMP/GMP/G600 group versus 11/80 in control groups; risk ratio (RR) 1.27, 95% CI 0.53 to 3.03; low-quality evidence). The findings for adverse events were also uncertain (2/40 in SMP/GMP/G600 group versus 3/80 in control groups; RR 1.33, 95% CI 0.23 to 7.66; low-quality evidence). Gastrointestinal events were the most commonly reported adverse effects. Pain from self reported gout flares (measured on a 10-point Likert scale) improved slightly more in the SMP/GMP/G600 group compared with controls (mean ± SD reduction -1.97 ± 2.28 points in SMP/GMP/G600 group versus -0.94 ± 2.25 in control groups; MD -1.03, 95% CI -1.96 to -0.10; low-quality evidence). This was an absolute reduction of 10% (95% CI 20% to 1% reduction), which may not be of clinical relevance. Results were imprecise for the outcome improvement in physical function (mean ± SD Health Assessment Questionnaire (HAQ)-II (scale 0 to 3, 0 = no disability): 0.08 ± 0.23 in SMP/GMP/G60 group versus 0.11 ± 0.31 in control groups; MD -0.03, 95% CI -0.14 to 0.08; low-quality evidence). Similarly, results for sUA reduction were imprecise (mean ± SD reduction: -0.025 ± 0.067 mmol/L in SMP/GMP/G60 group versus -0.010 ± 0.069 in control groups; MD -0.01, 95% CI -0.04 to 0.01; low-quality evidence). The study did not report tophus regression and health-related quality of life impact.One trial including 40 participants, at moderate to high risk of bias, compared vitamin C alone with allopurinol and with allopurinol plus vitamin C in a three-arm trial. We only compared vitamin C with allopurinol in this review. Participants were predominantly middle-aged men, and their severity of gout was representative of gout in general. The effect of vitamin C on the rate of gout attacks was not assessed. Vitamin C did not lower sUA as much as allopurinol (-0.014 mmol/L in vitamin C group versus -0.118 mmol/L in allopurinol group; MD 0.10, 95% CI 0.06 to 0.15; low-quality evidence). The study did not assess tophus regression, pain reduction or disability or health-related quality of life impact. The study reported no adverse events and no participant withdrawal due to adverse events. AUTHORS' CONCLUSIONS While dietary supplements may be widely used for gout, this review has shown a paucity of high-quality evidence assessing dietary supplementation.
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Affiliation(s)
- Mariano Andrés
- Sección de Reumatología, Hospital General Universitario de Alicante, C/ Pintor Baeza, 12, Alicante, Spain, 03010
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Stamp LK, O'Donnell JL, Frampton C, Drake JM, Zhang M, Chapman PT. Clinically insignificant effect of supplemental vitamin C on serum urate in patients with gout: a pilot randomized controlled trial. ACTA ACUST UNITED AC 2013; 65:1636-42. [PMID: 23681955 DOI: 10.1002/art.37925] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 02/28/2013] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Studies in human volunteers have shown that vitamin C reduces serum urate (SU) levels. The aim of this study was to determine the effects of vitamin C on SU levels in patients with gout. METHODS Patients with gout and an SU level >0.36 mmoles/liter (6 mg/dl) were recruited. Twenty patients already taking allopurinol were randomized to receive an increase in the dose of allopurinol or to commence taking vitamin C (500 mg/day). Twenty patients who had not been taking allopurinol were randomized to start receiving either allopurinol (up to 100 mg/day) or vitamin C (500 mg/day). Levels of plasma ascorbate, creatinine, and SU were measured on day 0 and week 8. RESULTS There was no significant difference in the baseline SU level or estimated glomerular filtration rate (eGFR) between those who received vitamin C and those who did not (for SU, mean ± SEM 0.50 ± 0.11 mmoles/liter [8.4 ± 1.8 mg/dl] versus 0.50 ± 0.09 mmoles/liter [8.4 ± 1.5 mg/dl]; for eGFR, mean ± SEM 65.5 ± 3.5 ml/minute/1.73 m(2) versus 67.9 ± 4.6 ml/minute/1.73 m(2) ). Among the randomized patients, 30% in the vitamin C group and 25% in the no vitamin C control group were receiving diuretics. In the patients receiving vitamin C, there was a significant increase between day 0 and week 8 in the plasma ascorbate level. The reduction in SU level over 8 weeks was significantly less in those patients receiving vitamin C compared to those who started or increased the dose of allopurinol (mean reduction 0.014 mmoles/liter [0.23 mg/dl] versus 0.118 mmoles/liter [1.9 mg/dl]; P < 0.001). CONCLUSION A modest dosage of vitamin C (500 mg/day) for 8 weeks had no clinically significant urate-lowering effects in patients with gout, despite the fact that plasma ascorbate levels increased. These results differ from previous findings in healthy control subjects with hyperuricemia. The uricosuric effect of modest-dose vitamin C appears to be small in patients with gout, when administered as monotherapy or in combination with allopurinol.
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Affiliation(s)
- Lisa K Stamp
- University of Otago, Christchurch, Christchurch, New Zealand.
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Torralba KD, De Jesus E, Rachabattula S. The interplay between diet, urate transporters and the risk for gout and hyperuricemia: current and future directions. Int J Rheum Dis 2012; 15:499-506. [DOI: 10.1111/1756-185x.12010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karina D. Torralba
- Division of Rheumatology; Keck School of Medicine; University of Southern California; Los Angeles; California; USA
| | - Emerson De Jesus
- Department of Internal Medicine; University of California-San Francisco; Fresno; California; USA
| | - Shylaja Rachabattula
- Division of Rheumatology; Keck School of Medicine; University of Southern California; Los Angeles; California; USA
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de Oliveira EP, Burini RC. High plasma uric acid concentration: causes and consequences. Diabetol Metab Syndr 2012; 4:12. [PMID: 22475652 PMCID: PMC3359272 DOI: 10.1186/1758-5996-4-12] [Citation(s) in RCA: 268] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 04/04/2012] [Indexed: 12/22/2022] Open
Abstract
High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides) in the liver is associated with the de novo synthesis of purine, accelerating UA production. The role played by diet on hyperuricemia has not yet been fully clarified, but high intake of fructose-rich industrialized food and high alcohol intake (particularly beer) seem to influence uricemia. It is not known whether UA would be a causal factor or an antioxidant protective response. Most authors do not consider the UA as a risk factor, but presenting antioxidant function. UA contributes to > 50% of the antioxidant capacity of the blood. There is still no consensus if UA is a protective or a risk factor, however, it seems that acute elevation is a protective factor, whereas chronic elevation a risk for disease.
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Affiliation(s)
- Erick Prado de Oliveira
- Center for exercise metabolism and nutrition (CeMENutri), Department of Public Health, Botucatu School of Medicine (UNESP), Botucatu, Brazil
- Department of Pathology, Botucatu School of Medicine (UNESP), Botucatu, Brazil
- CeMENutri-Faculdade de Medicina, Departamento de Saúde Pública (FMBUNESP), Distrito de Rubião Jr, s/n, 18.618-970 Botucatu, SP, Brazil
| | - Roberto Carlos Burini
- Center for exercise metabolism and nutrition (CeMENutri), Department of Public Health, Botucatu School of Medicine (UNESP), Botucatu, Brazil
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Zhang M, Chang H, Gao Y, Wang X, Xu W, Liu D, Li G, Huang G. Major dietary patterns and risk of asymptomatic hyperuricemia in Chinese adults. J Nutr Sci Vitaminol (Tokyo) 2012; 58:339-45. [PMID: 23327969 DOI: 10.3177/jnsv.58.339] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this study, we conducted a case-control study to evaluate the association of major dietary patterns and asymptomatic hyperuricemia taking account of blood lipids in Chinese adults. 187 cases with confirmed asymptomatic hyperuricemia and 187 controls were frequency matched on age, gender and area of residence. We conducted factor analysis using dietary information from a validated food frequency questionnaire to derive dietary patterns. The association between major dietary patterns and asymptomatic hyperuricemia was assessed by logistic regression analysis. Three major dietary patterns were found: 1) "animal products and fried food," 2) "western," 3) "soybean products and fruit." In multivariate analyses the "animal products and fried food" pattern score was associated with an odds ratio (OR) of 2.15 (95% CI, 1.22-3.76) compared with the lowest tertile. The OR for the top tertile of score for "soybean products and fruit" pattern was 0.32 (95% CI, 0.19-0.57) compared with the lowest tertile of "soybean products and fruit" pattern score. The significant association of these two patterns and asymptomatic hyperuricemia persisted after further adjusting for blood lipids. On the other hand, the "western" pattern was not associated with asymptomatic hyperuricemia. We observed a positive relationship between the "animal products and fried food" pattern and asymptomatic hyperuricemia, and a negative relationship between the "soybean products and fruit" pattern and asymptomatic hyperuricemia, independent of blood lipids.
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Affiliation(s)
- Meilin Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China
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Hameed FA. Gout. Integr Med (Encinitas) 2012. [DOI: 10.1016/b978-1-4377-1793-8.00049-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Juraschek SP, Miller ER, Gelber AC. Effect of oral vitamin C supplementation on serum uric acid: a meta-analysis of randomized controlled trials. Arthritis Care Res (Hoboken) 2011; 63:1295-306. [PMID: 21671418 DOI: 10.1002/acr.20519] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To assess the effect of vitamin C supplementation on serum uric acid (SUA) by pooling the findings from published randomized controlled trials (RCTs). METHODS A total of 2,082 publications identified through systematic search were subjected to the following inclusion criteria: 1) RCTs conducted on human subjects, 2) reported end-trial SUA means and variance, 3) study design with oral vitamin C supplementation and concurrent control groups, and 4) trial duration of at least 1 week. Trials that enrolled children or patients receiving dialysis were excluded. Two investigators independently abstracted trial and participant characteristics. SUA effects were pooled by random-effects models and weighted by inverse variance. RESULTS Thirteen RCTs were identified in the Medline, EMBase, and Cochrane Central Register of Controlled Trials databases. The total number of participants was 556, the median dosage of vitamin C was 500 mg/day, trial size ranged from 8-184 participants, and the median study duration was 30 days. Pretreatment SUA values ranged from 2.9-7.0 mg/dl (Système International d'Unités [SI units]: 172.5-416.4 μmoles/liter). The combined effect of these trials was a significant reduction in SUA of -0.35 mg/dl (95% confidence interval -0.66, -0.03 [P = 0.032]; SI units: -20.8 μmoles/liter). Trial heterogeneity was significant (I(2) = 77%, P < 0.01). Subgroup analyses based on trial characteristics indicated larger reductions in uric acid in trials that were placebo controlled. CONCLUSIONS In aggregate, vitamin C supplementation significantly lowered SUA. Future trials are needed to determine whether vitamin C supplementation can reduce hyperuricemia or prevent incident and recurrent gout.
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Affiliation(s)
- Stephen P Juraschek
- Johns Hopkins University School of Medicine, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21224, USA
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Abstract
During the past few decades, the mean serum uric acid levels and the prevalence of hyperuricemia in the general population appear to have increased. Correspondingly, the prevalence and incidence of gout have doubled. Potential reasons behind these trends include the increasing prevalence of obesity and metabolic syndrome, Western lifestyle factors, increased prevalence of medical conditions (eg, renal conditions, hypertension, and cardiovascular disorders), and use of medications that increase uric acid levels (eg, diuretics and low-dose aspirin). The substantial increase in sugar-sweetened soft drinks and associated fructose consumption also has coincided with the secular trend of hyperuricemia and gout. Recently, several large-scale epidemiologic studies have clarified a number of these long-suspected risk factors in relation with hyperuricemia and gout. Furthermore, recent studies have illuminated the substantial comorbidities of hyperuricemia and gout, particularly metabolic-cardiovascular-renal conditions. Although many prospective studies have suggested an independent association between serum uric acid levels and the future risk of cardiovascular-metabolic morbidities and mortality, only a limited number of randomized clinical trials and observational studies recently have shown that the use of allopurinol can be beneficial against these outcomes. Because these data are scarce and the effects of allopurinol might not be limited to decreasing serum uric acid levels, the potential causal role of uric acid on these outcomes remains to be clarified with further studies.
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Affiliation(s)
- Young Hee Rho
- Section of Rheumatology and the Clinical Epidemiology Unit, Boston University School of Medicine
| | - Yanyan Zhu
- Section of Rheumatology and the Clinical Epidemiology Unit, Boston University School of Medicine
| | - Hyon K. Choi
- Section of Rheumatology and the Clinical Epidemiology Unit, Boston University School of Medicine
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Choi HK. A prescription for lifestyle change in patients with hyperuricemia and gout. Curr Opin Rheumatol 2010; 22:165-72. [PMID: 20035225 DOI: 10.1097/bor.0b013e328335ef38] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW This review summarizes the recent data on lifestyle factors that influence serum uric acid levels and the risk of gout and attempts to provide holistic recommendations, considering both their impact on gout as well as on other health implications. RECENT FINDINGS Large-scale studies have clarified a number of long-suspected relations between lifestyle factors, hyperuricemia, and gout, including purine-rich foods, dairy foods, various beverages, fructose, and vitamin C supplementation. Furthermore, recent studies have identified the substantial burden of comorbidities among patients with hyperuricemia and gout. SUMMARY Lifestyle and dietary recommendations for gout patients should consider overall health benefits and risk, since gout is often associated with the metabolic syndrome and an increased future risk of cardiovascular disease (CVD) and mortality. Weight reduction with daily exercise and limiting intake of red meat and sugary beverages would help reduce uric acid levels, the risk of gout, insulin resistance, and comorbidities. Heavy drinking should be avoided, whereas moderate drinking, sweet fruits, and seafood intake, particularly oily fish, should be tailored to the individual, considering their anticipated health benefits against CVD. Dairy products, vegetables, nuts, legumes, fruits (less sugary ones), and whole grains are healthy choices for the comorbidities of gout and may also help prevent gout by reducing insulin resistance. Coffee and vitamin C supplementation could be considered as preventive measures as these can lower urate levels, as well as the risk of gout and some of its comorbidities.
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Affiliation(s)
- Hyon K Choi
- Section of Rheumatology and the Clinical Epidemiology Unit, Boston, Massachusetts 02118, USA.
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Chen JY, Chang CY, Feng PH, Chu CC, So EC, Hu ML. Plasma vitamin C is lower in postherpetic neuralgia patients and administration of vitamin C reduces spontaneous pain but not brush-evoked pain. Clin J Pain 2009; 25:562-9. [PMID: 19692796 DOI: 10.1097/ajp.0b013e318193cf32] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Plasma vitamin C concentrations have been suggested to be related to pain modulation in postherpetic neuralgia (PHN), an intractable neuropathic pain syndrome. In this study, we first compared plasma concentrations of vitamin C between healthy volunteers and PHN patients and then designed a symptom-based and mechanism-based approach to assess the analgesic effect of intravenous vitamin C on spontaneous and brush-evoked pain. METHODS Study 1 was cross-sectional that enrolled 39 healthy volunteers and 38 PHN patients. Study 2 was a double-blinded, placebo-controlled intervention study, which comprised 41 patients randomly allocated into the ascorbate group and placebo. Each patient received normal saline infusion with or without ascorbate on days 1, 3, and 5 and answered questionnaires that included side effects; numeric rating pain scale (NRS) on spontaneous and brush-evoked pain on days 1, 3, 5, and 7; and patient global impression of change on spontaneous and brush-evoked pain on day 7. RESULTS Study 1 revealed that plasma concentrations of vitamin C were significantly lower in patients with PHN than in healthy volunteers (P<0.001). Study 2 showed that ascorbate treatment effectively restored plasma vitamin C concentrations in the patients and decreased spontaneous pain by 3.1 in NRS from baseline to day 7, as compared with a decrease of 0.85 in NRS by placebo treatment (P<0.001). Conversely, ascorbate treatment did not significantly affect brush-evoked pain. Ascorbate treatment also resulted in a better efficacy than placebo in patient global impression of change on spontaneous pain (P<0.001) on day 7 and did not affect brush-evoked pain. No side effects were observed. CONCLUSIONS Plasma vitamin C status plays a role in PHN, and intravenous ascorbate helps relieve spontaneous pain in PHN.
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Affiliation(s)
- Jen-Yin Chen
- Departments of Anesthesiology, Chi-Mei Foundation Hospital, Taichung, Taiwan
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Choi HK, Gao X, Curhan G. Vitamin C intake and the risk of gout in men: a prospective study. ACTA ACUST UNITED AC 2009; 169:502-7. [PMID: 19273781 DOI: 10.1001/archinternmed.2008.606] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Several metabolic studies and a recent double-blind, placebo-controlled, randomized trial have shown that higher vitamin C intake significantly reduces serum uric acid levels. Yet the relation with risk of gout is unknown. METHODS We prospectively examined, from 1986 through 2006, the relation between vitamin C intake and risk of incident gout in 46 994 male participants with no history of gout at baseline. We used a supplementary questionnaire to ascertain the American College of Rheumatology criteria for gout. Vitamin C intake was assessed every 4 years through validated questionnaires. RESULTS During the 20 years of follow-up, we documented 1317 confirmed incident cases of gout. Compared with men with vitamin C intake less than 250 mg/d, the multivariate relative risk (RR) of gout was 0.83 (95% confidence interval [CI], 0.71-0.97) for total vitamin C intake of 500 to 999 mg/d, 0.66 (0.52-0.86) for 1000 to 1499 mg/d, and 0.55 (0.38-0.80) for 1500 mg/d or greater (P < .001 for trend). The multivariate RR per 500-mg increase in total daily vitamin C intake was 0.83 (95% CI, 0.77-0.90). Compared with men who did not use supplemental vitamin C, the multivariate RR of gout was 0.66 (95% CI, 0.49-0.88) for supplemental vitamin C intake of 1000 to 1499 mg/d and 0.55 (0.36-0.86) for 1500 mg/d or greater (P < .001 for trend). CONCLUSIONS Higher vitamin C intake is independently associated with a lower risk of gout. Supplemental vitamin C intake may be beneficial in the prevention of gout.
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Affiliation(s)
- Hyon K Choi
- Division of Rheumatology, Department of Medicine, Arthritis Research Centre of Canada, Vancouver General Hospital, University of British Columbia, Vancouver, Canada.
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Forman JP, Choi H, Curhan GC. Fructose and vitamin C intake do not influence risk for developing hypertension. J Am Soc Nephrol 2009; 20:863-71. [PMID: 19144761 DOI: 10.1681/asn.2008050473] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Higher uric acid levels are associated with an increased risk for developing hypertension. Higher intake of fructose increases plasma uric acid levels and higher intake of vitamin C reduces uric acid levels, but whether these nutrients are independently associated with the risk for developing hypertension is unknown. We studied this question by analyzing data from participants of three large and independent prospective cohorts: Nurses' Health Study 1 (n = 88,540), Nurses' Health Study 2 (n = 97,315), and the Health Professionals Follow-up Study (n = 37,375). Relative risks and 95% confidence intervals for incident hypertension were computed according to quintiles of fructose intake and categories of vitamin C intake using multivariable Cox proportional hazards regression. Fructose intake was not associated with the risk for developing hypertension; the multivariable relative risks (95% confidence intervals) for the highest compared with the lowest quintile of fructose intake were 1.02 (0.99 to 1.06) in Nurses' Health Study 1, 1.03 (0.98 to 1.08) in Nurses' Health Study 2, and 0.99 (0.93 to 1.05) in Heath Professionals Follow-up Study. Regarding vitamin C, the relative risks for individuals who consumed > or =1500 mg/d compared with those who consumed <250 mg/d were 0.89 (0.83 to 0.96) in Nurses' Health Study 1, 1.02 (0.91 to 1.14) in Nurses' Health Study 2, and 1.06 (0.97 to 1.15) in Health Professionals Follow-up Study. In conclusion, fructose and vitamin C intake do not substantially influence the risk for developing hypertension.
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Affiliation(s)
- John P Forman
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, 3rd Floor, 181 Longwood Avenue, Boston, Massachusetts 02115, USA.
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Abstract
PURPOSE OF REVIEW This review summarizes recent epidemiologic research findings on gout, and attempts to put them into the context of clinical and public health decision-making aimed at prevention and improved management of gout. RECENT FINDINGS A large prospective study found that coffee consumption was inversely associated with risk of gout and that consumption of sugar-sweetened soft drinks or fructose was strongly associated with an increased gout risk. Studies based on the Third National Health and Nutrition Examination Survey (NHANES III) suggest that these consumptions affect serum uric acid levels parallel to the direction of gout risk. Furthermore, data from NHANES III show a remarkably high prevalence of the metabolic syndrome among individuals with gout. Prospective studies found an increased risk of myocardial infarction and cardiovascular mortality in gout patients. SUMMARY Lifestyle and dietary recommendations for gout patients should consider other health benefits, since gout is often associated with major chronic disorders such as the metabolic syndrome and an increased risk for cardiovascular disease and mortality. In addition to recent dietary recommendations, gout patients should be advised to limit fructose intake. The inverse link between coffee and the risk of gout suggests that coffee could be allowed among gout patients.
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Abstract
Gout is an inflammatory arthritis mediated by the crystallization of uric acid within the joints and often is associated with hyperuricemia. Data suggest that the overall disease burden of gout remains substantial and may be increasing. Identifying and characterizing modifiable risk factors for gout is a major step in preventing and managing this painful condition. As more scientific data on the risk factors and comorbidities of gout become available, their integration into gout prevention and care strategies may become essential. This article reviews the relevant epidemiologic data, with a focus on recent progress and data on other crystal arthropathies.
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Affiliation(s)
- Hyon Choi
- Division of Rheumatology, Vancouver General Hospital, The University of British Columbia, Arthritis Research Centre of Canada, Suite 300, 895 West 10th Avenue, Vancouver, BC V5Z 1L7, Canada.
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Abstract
Gout affects more than 1% of adults in the USA, and it is the most common form of inflammatory arthritis among men. Accumulating data support an increase in the prevalence of gout that is potentially attributable to recent shifts in diet and lifestyle, improved medical care, and increased longevity. There are both nonmodifiable and modifiable risk factors for hyperuricemia and gout. Nonmodifiable risk factors include age and sex. Gout prevalence increases in direct association with age; the increased longevity of populations in industrialized nations may contribute to a higher prevalence of gout through the disorder's association with aging-related diseases such as metabolic syndrome and hypertension, and treatments for these diseases such as thiazide diuretics for hypertension. Although gout is considered to be primarily a male disease, there is a more equal sex distribution among elderly patients. Modifiable risk factors for gout include obesity, the use of certain medications, high purine intake, and consumption of purine-rich alcoholic beverages. The increasing prevalence of gout worldwide indicates that there is an urgent need for improved efforts to identify patients with hyperuricemia early in the disease process, before the clinical manifestations of gout become apparent.
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Affiliation(s)
- Kenneth G Saag
- UAB Center for Education and Research (CERTs) on Therapeutics of Musculoskeletal Disorders, Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Abstract
The disease burden of gout remains substantial and may be increasing as a result of trends in demographics and lifestyles. Recent scientific data serve to illuminate the links between dietary and other factors and risk for gout. These lifestyle factors affect not only the risk for gout, but also are risk factors for other chronic diseases of public health importance. Accordingly, dietary and lifestyle recommendations related to gout should consider their effect on many diseases beyond gout. These recommendations should reinforce established recommendations where the influence on gout parallels the influence on other diseases, and consider modifying the recommendations where they are divergent.
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Affiliation(s)
- Hyon K Choi
- Rheumatology Unit, Bulfinch 165, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
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Huang HY, Appel LJ, Choi MJ, Gelber AC, Charleston J, Norkus EP, Miller ER. The effects of vitamin C supplementation on serum concentrations of uric acid: results of a randomized controlled trial. ACTA ACUST UNITED AC 2005; 52:1843-7. [PMID: 15934094 DOI: 10.1002/art.21105] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Reductions in serum uric acid levels are clinically relevant. Previous studies have suggested a uricosuric effect of vitamin C. Whether vitamin C reduces serum uric acid is unknown. We undertook this study to determine the effects of vitamin C supplementation on serum uric acid concentrations. METHODS The study was a double-blinded placebo-controlled randomized trial conducted in research units affiliated with an academic institution. Study participants were 184 nonsmokers, randomized to take either placebo or vitamin C supplements (500 mg/day) for 2 months. RESULTS At the end of the study period, serum uric acid levels were significantly reduced in the vitamin C group (mean change -0.5 mg/dl [95% confidence interval -0.6, -0.3]), but not in the placebo group (mean change 0.09 mg/dl [95% confidence interval -0.05, 0.2]) (P < 0.0001). The same pattern of results was evident in subgroups defined by age, sex, race, body mass index, chronic illness, diuretic use, and quartiles of baseline serum ascorbic acid levels. In the subgroups, from the lowest to the highest quartile of baseline serum uric acid, net mean changes (95% confidence intervals) in serum uric acid with vitamin C supplementation were -0.4 (-0.8, 0.01), -0.5 (-0.9, -0.2), -0.5 (-0.8, -0.2), and -1.0 (-1.6, -0.4) mg/dl (P = 0.06, 0.005, 0.003, and 0.002, respectively). Compared with placebo, vitamin C increased the estimated glomerular filtration rate. CONCLUSION Supplementation with 500 mg/day of vitamin C for 2 months reduces serum uric acid, suggesting that vitamin C might be beneficial in the prevention and management of gout and other urate-related diseases.
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Affiliation(s)
- Han-Yao Huang
- Johns Hopkins University, Baltimore, Maryland 21205, USA.
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Johnston C. Potential Adverse Effects of Vitamins C and E. Antioxidants (Basel) 2003. [DOI: 10.1201/9781439822173.ch8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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McGrowder D, Ragoobirsingh D, Dasgupta T. The enhancement of the hyperglycemic effect of S-nitrosoglutathione and S-nitroso-N-acetylpenicillamine by vitamin C in an animal model. BMC Pharmacol 2002; 2:18. [PMID: 12230634 PMCID: PMC130025 DOI: 10.1186/1471-2210-2-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2002] [Accepted: 09/13/2002] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND S-nitrosoglutathione (GSNO) and S-nitroso-N-acetlypenicillamine (SNAP) are two of the most common sources of nitric oxide (NO) in the biomedical field. Vitamin C has been known to accelerate the decomposition of GSNO and SNAP increasing the release and availability of NO which is cytotoxic at non-physiological concentrations. The study investigates any potential detrimental effect of vitamin C and GSNO, vitamin C and SNAP on glucose metabolism in normotensive and normoglycemic dogs. RESULTS The results showed that administration of vitamin C (50 mg/kg) and GSNO (35 mg/kg & 50 mg/kg), or vitamin C (50 mg/kg) and SNAP (10 mg/kg) to overnight fasted dogs resulted in significant elevation of the blood glucose levels, attaining maximum level at the 2.0 or 2.5 h time point postprandially. The elevated blood glucose levels were due to significant reduction in plasma insulin levels in the dogs treated with vitamin C and GSNO, or vitamin C and SNAP (P < 0.05). The decreased insulin response was associated with significant elevation of nitric oxide produced from GSNO and SNAP co-administered with vitamin C, as assessed by plasma nitrate/nitrite levels. CONCLUSIONS The results indicate that enhanced NO release by vitamin C affects postprandial blood glucose and plasma insulin levels and the reduced glucose tolerance is mainly due to impaired insulin release. The clinical relevance of the findings of this study suggest that hypertensive diabetic patients treated with GSNO or SNAP, who are on vitamin C supplements may be more predisposed to further decrease in their glycemic control.
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Affiliation(s)
- Donovan McGrowder
- Department of Basic Medical Sciences (Biochemistry Section) and Department of Chemistry, University of The West Indies, Mona, Kingston 7, Jamaica, West Indies
| | - Dalip Ragoobirsingh
- Department of Basic Medical Sciences (Biochemistry Section) and Department of Chemistry, University of The West Indies, Mona, Kingston 7, Jamaica, West Indies
| | - Tara Dasgupta
- Department of Basic Medical Sciences (Biochemistry Section) and Department of Chemistry, University of The West Indies, Mona, Kingston 7, Jamaica, West Indies
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Abstract
Dietary reference intakes (DRIs) for vitamin C for healthy U.S. populations are currently being formulated by the Panel on Dietary Antioxidants and Related Compounds of the Food and Nutrition Board of the Institute of Medicine. A major task of the Panel is to analyze the evidence of adverse effects of high-dose vitamin C intakes to derive, if appropriate, a Tolerable Upper Intake Level (UL) for vitamin C. The present report details current and past research examining potential adverse effects of supplemental vitamin C. The available data indicate that very high intakes of vitamin C (2-4 g/day) are well tolerated biologically in healthy mammalian systems. Currently, strong scientific evidence to define and defend a UL for vitamin C is not available.
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Affiliation(s)
- C S Johnston
- Foods and Nutrition Laboratories, Arizona State University, Tempe 85287-2502, USA
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Diplock AT, Charleux JL, Crozier-Willi G, Kok FJ, Rice-Evans C, Roberfroid M, Stahl W, Viña-Ribes J. Functional food science and defence against reactive oxidative species. Br J Nutr 1998; 80 Suppl 1:S77-112. [PMID: 9849355 DOI: 10.1079/bjn19980106] [Citation(s) in RCA: 409] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This paper assesses critically the science base that underpins the argument that oxidative damage is a significant causative factor in the development of human diseases and that antioxidants are capable of preventing or ameliorating these disease processes. The assessment has been carried out under a number of headings, and some recommendations for future research are made based on the present day knowledge base. The knowledge database (1) Consideration of the basic science that underlies understanding of the role of free radicals in causing cellular pathologies, and the role of antioxidants in preventing this, shows that an imbalance of reactive oxygen species and antioxidant defence systems may lead to chemical modifications of biologically relevant macromolecules. This imbalance provides a logical pathobiochemical mechanism for the initiation and development of several disease states. Experimental data obtained in vivo provide evidence that antioxidants function in systems that scavenge reactive oxygen species and that these are relevant to what occurs in vivo. The relevance in vivo of these observations depends inter alia on knowledge of the uptake and distribution of the antioxidant within the human body, and on what tissue levels of the antioxidant may be expected in relation to dietary levels. (2) There is some way to go until validated precise methods are available for measuring biomarkers of oxidative damage in human subjects in vivo under minimally invasive conditions. With respect to oxidative damage in DNa, HPLC and GC-mass spectrophotometry methods have both merits and limitations. Lipid oxidation products in plasma are best measured as isoprostanes or as lipid hydroperoxides using specific HPLC techniques. Development of isoprostane measurement will advance specificity and precision. The measurement of oxidative damage to proteins has some potential but such methods have not been effectively exploited. (3) Epidemiological studies support the hypothesis that the major antioxidant nutrients vitamin E and vitamin C, and beta-carotene (which may or may not be acting as an antioxidant in vivo), may play a beneficial role in prevention of several chronic disorders. More research is needed on the impact of other non-nutrient compounds, such as other carotenoids and flavonoids, on human health. In general, human intervention studies using hard end-points are the gold standard. Trials are restricted mainly to the major antioxidants and do not allow firm conclusions because of inconsistent findings, an insufficient number of studies and the use of varying doses. There is evidence that large doses of beta-carotene may be deleterious to the health of certain subgroups of the population such as heavy habitual smokers. (4) With respect to the safety of administration of supplementary vitamins, vitamin C is safe at levels of supplementation up to 600 mg/d, and higher levels, up to 2000 mg/d, are without risk. Vitamin E has a very low human toxicity and an intake of 1000 mg/d is without risk; 3200 mg/d has been shown to be without any consistent risk. Large intakes of beta-carotene must be viewed with caution because they have been shown to confer detriment to a population at high risk of lung cancer when administered after many years of high risk (smoking) behaviour. Until further work clarifies the situation in heavy smokers with respect to taking supplements, larger doses should be avoided by such individuals. There is little reliable information about the human toxicology of flavonoids and related non-nutrient antioxidant constituents of the diet. (5) The food industry has long experience in the control of oxidative damage in foods and this experience can be used to advantage for the protection of food antioxidants which are beneficial. Some of these, such as vitamins C and E and beta-carotene, are well known, and strategies for their protection in foods are already exploited by food technologies. (ABSTRACT TRUNCATED)
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Affiliation(s)
- A T Diplock
- International Antioxidant Research Centre, UMDS, Guy's Hospital, London, UK
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Graumlich JF, Ludden TM, Conry-Cantilena C, Cantilena LR, Wang Y, Levine M. Pharmacokinetic model of ascorbic acid in healthy male volunteers during depletion and repletion. Pharm Res 1997; 14:1133-9. [PMID: 9327438 DOI: 10.1023/a:1012186203165] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE To develop a new pharmacokinetic model for ascorbic acid (vitamin C) since no previously published model describes ascorbic acid absorption and disposition over a broad physiologic range of doses and plasma concentrations. METHODS A new model was developed through exploratory simulations. The model was fitted to pharmacokinetic data obtained from seven healthy volunteers who underwent ascorbic acid depletion then gradual repletion. Concentrations of ascorbic acid were measured in plasma and urine. Final pharmacokinetic model parameter estimates were obtained using nonlinear regression analysis. RESULTS The new model included saturable absorption, distribution and renal tubular reabsorption parameters. The model described ascorbic acid concentrations in plasma, cells, and urine during depletion and gradual repletion phases with a residual error less than 15%. CONCLUSIONS The model was useful for obtaining a new understanding of the likely causes for the complex concentration-time profile observed during gradual repletion. At doses of 200 to 2500 mg per day, the plateau in pre-dose concentrations is largely due to apparent saturation of tissue uptake and less a function of oral bioavailability and renal excretion than previously thought.
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Affiliation(s)
- J F Graumlich
- Department of Biomedical and Therapeutic Sciences, University of Illinois College of Medicine, Peoria 61656-1649, USA.
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Abstract
Interest in a putative disease-preventive role for the so-called antioxidant nutrients derives from a large body of evidence suggesting that oxidative damage is a contributing cause of many life-shortening diseases. Since their use is an otherwise healthy population, it is important that such agents be virtually free of toxicity. The agents of most interest are alpha-tocopherol (vitamin E), ascorbic acid (vitamin C) and beta-carotene. When used for disease prevention, the doses given are several-fold greater the Recommended Dietary Allowance (RDA), the latter being based on amounts necessary for the prevention of classic deficiency conditions recognised decades ago. alpha-Tocopherol, ascorbic acid and beta-carotene are remarkably well tolerated and free from toxicity. Consequently, they are well suited for testing as preventive agents, since their use does not require any toxicity monitoring except in unusual circumstances. An example of the latter would be in patients who are vitamin K deficient, perhaps through anticoagulation with drugs such as warfarin, in which case use of high doses of alpha-tocopherol may increase the bleeding tendency.
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Affiliation(s)
- H S Garewal
- Department of Veterans Affairs Medical Center, Tucson, Arizona, USA
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