Is tea consumption associated with the serum uric acid level, hyperuricemia or the risk of gout? A systematic review and meta-analysis

Association between Visceral Adiposity Index and Hyperuricemia among Steelworkers: The Moderating Effects of Drinking Tea

BACKGROUND/OBJECTIVES

Steelworkers are more likely to have a higher prevalence of hyperuricemia due to their exposure to special occupational factors and dietary habits. The interrelationships of visceral adiposity index (VAI), hyperuricemia, and drinking tea remain uncertain. This study aimed to assess the association between VAI and hyperuricemia among steelworkers, and if drinking tea modified this association.

METHODS

A total of 9928 steelworkers from Hunan Hualing Xiangtan Iron and Steel Company participated in this cross-sectional study. All participants completed a questionnaire, received anthropometric measurements, and provided blood samples for biochemical testing. Three logistic regression models were used to analyze the association between VAI and hyperuricemia.

RESULTS

In this study, the prevalence of hyperuricemia was approximately 23.74% (males: 24.41%; females: 20.63%), and a positive correlation between VAI and hyperuricemia risk was observed. In multivariate logistic regression analysis, the risk of hyperuricemia increased 1.76 times (95% CI: 1.64-1.89) and 2.13 times (95% CI: 1.76-2.57) with the increase of ln VAI in males and females, respectively. For males, compared to quartile 1, the risk of hyperuricemia in the second, third, and fourth quartile of VAI were 1.75 (95% CI: 1.11-2.71), 2.56 (95% CI: 1.67-3.93) and 4.89 (95% CI: 3.22-7.43). For females, compared to quartile 1, the risk of hyperuricemia in the second, third, and fourth quartile of VAI were 1.99 (95% CI: 1.40-2.82), 2.92 (95% CI: 1.96-4.34) and 4.51 (95% CI: 2.89-7.02). Additionally, our study found that, compared with not consuming tea, drinking tea could reduce uric acid levels by 0.014 in male steelworkers (t = -2.051, p = 0.040), 0.020 in workers consuming smoked food (t = -2.569, p = 0.010), and 0.022 in workers consuming pickled food (t = -2.764, p = 0.006).

CONCLUSIONS

In conclusion, VAI is positively correlated with hyperuricemia in steelworkers. Drinking tea may lower uric acid levels in male steelworkers and steelworkers who prefer smoked and pickled foods.

Effects of dietary factors on hyperuricaemia and gout: a systematic review and meta-analysis of observational studies

This study aimed to gather the best evidence on the relationship between dietary factors and hyperuricaemia and gout. We searched databases including PubMed, Embase, Cochrane, and Web of Science from database creation to July 2023. Meta-analysis showed that consumption of alcohol (OR: 1.41, 95% CI: 1.29-1.55; 1.60, 95% CI: 1.33-1.93, respectively), red meat (OR:1.27, 95% CI: 1.18-1.37; 1.32, 95% CI: 1.18-1.47, respectively), fructose (OR: 1.29, 95% CI: 1.21-1.38; 1.65, 95% CI: 1.36-2.01, respectively) and seafoods (OR: 1.40, 95% CI: 1.20-1.64; 1.29, 95% CI: 1.00-1.67, respectively) were positively associated with the risk of hyperuricaemia and gout, while vegetables (OR: 0.78, 95% CI: 0.71-0.85; 0.96,95% CI 0.74-1.24, respectively) were inversely associated. Dairy products (OR: 0.69, 95% CI: 0.61-0.78) and nuts (OR: 0.75, 95% CI: 0.60-0.93) were also inversely associated with the risk of hyperuricaemia. Soy products (OR: 0.86, 95% CI: 0.75-0.98) and coffee (OR: 0.56, 95% CI: 0.39-0.81) were negatively associated with the risk of gout.

Distinguishable short-term effects of tea and water drinking on human saliva redox

Food consumption can alter the biochemistry and redox status of human saliva, and the serving temperature of food may also play a role. The study aimed to explore the immediate (3 min) and delayed (30 min) effects of hot tea (57 ± 0.5 °C) ingestion and cold tea (8 ± 0.5 °C) ingestion on the salivary flow rate and salivary redox-relevant attributes. The saliva was collected from 20 healthy adults before, 3-min after and 30-min after the tea ingestion. The hot or cold deionised water at the same temperatures were used as control. The salivary flow rate and redox markers in hot tea (HBT), cold tea (CBT), hot water (HW) and cold water (CW) group were analysed and compared. The results demonstrated that neither the black tea nor the water altered the salivary flow rate; the black tea immediately increased the salivary thiol (SH) and malondialdehyde (MDA) content while reduced salivary uric acid (UA) significantly. The tea ingestion showed a tendency to elevate the ferric reducing antioxidant power (FRAP) in saliva, although not significantly. The water ingestion decreased the MDA content immediately and increased the UA level significantly. Cold water was found to induce a greater delayed increase in total salivary total protein (TPC) than the hot water. In conclusion, the black tea ingestion affects the redox attributes of human saliva acutely and significantly, while the temperature of drink makes the secondary contribution.

Effect of tea intake on genetic predisposition to gout and uric acid: a Mendelian randomization study

Objective

The effect of tea on gout and uric acid is still controversial. This study aims to analyze the effect of tea intake on genetic predisposition to gout, idiopathic gout, gout due to impairment of renal function as well as uric acid by Mendelian randomization (MR).

Methods

Forty independent single nucleotide polymorphisms (SNPs) associated with tea intake were selected from UK Biobank. SNPs for uric acid were obtained from BioBank Japan, SNPs for gout were obtained from UK Biobank, and SNPs for gout due to impairment of renal function and idiopathic gout were derived from FinnGen. The causal relationship of exposure-outcome was tested using inverse variance weighted, MR-Egger and weighted median. MR-Egger intercept was employed to assess horizontal pleiotropy, Cochran's Q test was used to assess heterogeneity, and leave-one-out sensitivity analysis was utilized to analyze the stability of the results.

Results

The results of MR analysis showed that tea intake was negatively associated with gout due to impairment of renal function (OR 0.997, 95% CI 0.994 to 0.999, P = 0.017), whereas there was no causal association with gout, idiopathic gout, and uric acid (P > 0.05), for which sensitivity analysis suggested that these results were robust.

Conclusions

There was a genetic predisposition effect of increased tea intake on the reduced risk of gout due to impairment of renal function, whereas there was no such effect on gout, idiopathic gout, and uric acid. Tea intake may become an important option in the dietary treatment of gout due to impairment of renal function.

Dose-response relationships of tea and coffee consumption with gout: a prospective cohort study in the UK Biobank

OBJECTIVES

The association of tea or coffee consumption with gout is inconsistently reported. Few prospective studies have explored their dose-response relationship. Therefore, we aimed to quantitatively investigate the association between tea, coffee and the risk of developing gout.

METHODS

The study included 447 658 participants in the UK Biobank who were initially free of gout. Tea and coffee consumption were assessed at baseline. We used Cox proportional hazards models to estimate the associations between tea/coffee consumption and incident gout, with restricted cubic spline added to the Cox models to evaluate the dose-response relationships.

RESULTS

During a median follow-up period of 13.42 years, we recorded 3,053 gout cases. The associations between tea, coffee and gout were nonlinear, with a significant reduction in the risk by ∼ six cups/day of tea and three cups/day of coffee. Compared with those who were not tea and coffee drinkers, those who consumed >6 cups/day of tea or coffee were associated with 23% (HR 0.77, 95% CI, 0.66, 0.91) and 40% (HR 0.60, 95% CI, 0.47, 0.77) lower risks of gout, respectively, and both caffeinated and decaffeinated coffee consumption were associated with a decreased risk. Moreover, hyperuricaemia may modify the association between coffee and gout. Compared with non-coffee consumers with hyperuricaemia, those with ≥4 cups/day coffee intake without hyperuricaemia had the lowest risk (HR 0.34, 95% CI, 0.28, 0.41).

CONCLUSION

Consumption of tea or coffee had a strong nonlinear association in gout risk reduction. Hyperuricaemia status had a potential effect modification on the association of coffee intake with gout.

Causal association between tea intake and risk for gout: a Mendelian randomization study

Background: Gout, an increasingly prevalent form of inflammatory arthritis, is caused by the accumulation of uric acid crystals in joints, resulting in severe pain, swelling and stiffness that adversely affect physical, mental and emotional wellbeing. The management of gout requires a combination of medication and lifestyle modifications. Recent studies suggest that tea intake may reduce the risk of developing gout; however, further research is needed to establish a causal relationship. Methods: In this study, we employed a bidirectional two-sample Mendelian randomization (MR) approach, utilizing genome-wide association study (GWAS) summary statistics, to investigate the causal association between increased tea intake and gout. We meticulously selected instrumental variables (IVs) based on rigorous criteria and employed five different MR methods. Heterogeneity was assessed using Cochran's Q statistic, and pleiotropy was evaluated using the MR Egger intercept and MR-PRESSO tests. Weak IVs were identified using F values. The Phenoscanner database was consulted to exclude single nucleotide polymorphisms associated with confounding factors or outcomes. Results: The study included one dataset related to tea intake (ukb-b-6066) and three datasets related to gout (ukb-b-12765, finn-b-M13_GOUT, and finn-b-GOUT_STRICT). Our forward MR analysis suggest a causal relationship between increased tea intake and reduced risk of gout in all three gout-related datasets [OR (95% CI): 0.9966 (0.9938-0.9993), p = 0.0167; 0.4842 (0.2683-0.8737), p-value = 0.0160; and 0.4554 (0.2155-0.9623), p = 0.0393, respectively]. The reveres MR showed increased risk of gout (ukb-b-12765) was significantly associated with low tea intake according to the IVW analysis [OR (95% CI): 0.0062 (0.0002-0.154), p = 0.0020]. However, this association was not observed in the Finn-b-M13_GOUT and Finn-b-GOUT_STRICT [OR (95% CI): 0.9992 (0.9909-1.0075), p = 0.8453 and OR (95% CI): 0.9996 (0.9932-1.0059), p = 0.8896, respectively]. No significant heterogeneity or potential pleiotropy was detected, and the possibility of weak IVs was also excluded. Conclusion: Our MR analysis suggest a causal relationship between genetically predicted tea intake and a decreased risk of gout. These findings underscore the potential advantages of increasing tea intake for preventing gout. However, further research is needed to validate these results and elucidate the underlying mechanisms.

Habitual Tea Consumption Increases the Incidence of Metabolic Syndrome in Middle-Aged and Older Individuals

In middle-aged and elderly individuals, the relationship between tea consumption and incident metabolic syndrome (MetS) is still unclear. Therefore, this study intends to figure out the relationship between tea-drinking frequency and MetS in rural middle-aged and older Chinese residents. In the Northeast China Rural Cardiovascular Health Study, 3632 middle-aged or older individuals (mean age 57 ± 8, 55.2% men) without MetS were included at baseline during 2012–2013 and were followed up on between 2015–2017. Participants showing differential tea consumption frequency were divided into the following classes: non-habitual tea drinkers, occasional tea drinkers, 1–2 times/day drinkers, and ≥3 times/day drinkers. Data showed that non-habitual tea drinking was more common among women. The frequency of tea consumption was higher in ethnic groups other than Han and among singles, as well as in concurrent smokers and drinkers and individuals with primary or lower educational status. The increasing tea consumption was in line with baseline elevations in body mass index, systolic and diastolic blood pressure, high-density lipoprotein cholesterol (HDL-C), and AST/ALT ratio. Multivariate logistic regression analysis confirmed that occasional tea drinking increased the incidence of low HDL-C [OR (95% CI): 1.268 (1.015, 1.584)], high waist circumference [OR (95% CI): 1.336 (1.102, 1.621)], and MetS [OR (95% CI): 1.284 (1.050, 1.570)]. In addition, 1–2 times/day tea drinking increased the cumulative incidence of high TG [OR (95% CI): 1.296 (1.040, 1.616)], high waist circumference [OR (95% CI): 1.296 (1.044, 1.609)] and MetS [OR (95% CI): 1.376 (1.030, 1.760)]. We demonstrated that regular tea consumption is correlated with a greater incidence of metabolic disorders and MetS. Our findings may help clarify the contradictory association reported between tea drinking and MetS development in middle-aged and older residents of rural China.

Interaction of Harmful Alcohol Use and Tea Consumption on Hyperuricemia Among Han Residents Aged 30-79 in Chongqing, China

Objective

The prevalence of hyperuricemia appears to be high worldwide. We aimed to explore the interaction between harmful alcohol use and tea consumption on hyperuricemia.

Methods

This study recruited 22,449 Han residents based on the data from the China Multi-Ethnic Cohort (CMEC) study, Chongqing province, to have a face-to-face electronic questionnaire, physical examination, and clinical laboratory tests. The difference in hyperuricemia between the different populations was compared by the Chi-square test. The interaction between harmful alcohol use and tea consumption was analyzed by the multivariate logistic regression model.

Results

Amongst 22,449 participants, the mean age was 51.5±11.8 years, and 46.83% of them were males. The proportion of harmful alcohol use, tea consumption, and harmful alcohol use and tea consumption were 14.01%, 21.01%, and 6.54%, respectively. Multivariate logistic regression showed that the odds ratio (OR) of harmful alcohol use and tea consumption (OR=2.21, 95% CI: 1.58-3.10) was greater than that of harmful alcohol use (OR=1.63, 95% CI:1.17-2.27) and tea consumption (OR=1.34, 95% CI:1.10-1.63). Among males, the results were similar (harmful alcohol use and tea consumption: OR=2.02, 95% CI: 1.43-2.84; harmful alcohol use: OR=1.61, 95% CI: 1.14-2.27; tea consumption: OR=1.28, 95% CI: 1.05-1.57). However, among females, the odds ratio of harmful alcohol use and tea consumption (OR=15.50, 95% CI: 1.36-176.50) was more than 10 times than that of only harmful alcohol use (OR=1.55, 95% CI: 0.42-5.69) or tea consumption (OR=1.22, 95% CI: 0.52-2.82).

Conclusion

The interaction of harmful alcohol use and tea consumption was a positive risk for hyperuricemia in Han residents aged 30-79 years in China.

Environmental Triggers of Hyperuricemia and Gout

Gout is the most prevalent type of inflammatory arthritis worldwide and environmental factors contribute to hyperuricemia and risk for gout flare. Causes of hyperuricemia include increased purine consumption from meat, alcohol, and high fructose corn syrup as well as medications such as cyclosporine, low-dose aspirin, or diuretics. Triggers for gout flares include increased purine consumption and medication use such as urate lowering therapy and diuretics. Environmental exposures including lead exposure, particulate matter exposure, temperature fluctuations, and physiologic stress have been found to trigger flares. In the right clinical scenario, these factors should be considered when treating gout patients.

Potential role of tea drinking in preventing hyperuricaemia in rats: biochemical and molecular evidence

BACKGROUND

Lifestyle and diet play a significant role in hyperuricaemia. Accumulating evidence indicates that tea consumption is associated with hyperuricaemia and gout. However, diverse compounds in different types of tea make it quite difficult to determine the relevant molecular mechanism. Here, we compared the effects of six types of tea on hyperuricaemia induced by potassium oxonate (PO) and hypoxanthine in rats and investigated the possible underlying mechanisms.

METHODS

Rats were randomly assigned to ten groups: the control, hyperuricaemia model, benzbromarone positive control, traditional Chinese medicine Simiao San positive control, green tea, yellow tea, black tea, white tea, red tea, and cyan tea treatment groups. After 21 days, uric acid (UA), xanthine oxidase (XOD), alanine aminotransferase (ALT),blood urea nitrogen (BUN), and creatinine (CRE) were assessed. Serum levels of interleukin-1β (IL-1β) were measured with an enzyme-linked immunosorbent assay. Haematoxylin-eosin staining and immunohistochemistry were used to assess liver and kidney injury.

RESULTS

The levels of UA, CRE, and BUN in the treatment group were decreased to varying degrees. There was a significant reduction in UA, CRE, and BUN levels for yellow tea compared to the positive control drugs. Yellow tea suppressed XOD activity and alleviated hepatic and kidney injury. Network pharmacology and untargeted metabolomics indicated that ten yellow tea bioactive ingredients and 35 targets were responsible for preventing hyperuricaemia, which was mediated by 94 signalling pathways, including IL-1β and TNF.

CONCLUSION

These findings indicate that green tea cannot reduce the serum uric acid level of hyperuricaemic rats. Yellow tea can significantly improve hyperuricaemia by regulating the inflammatory response, autophagy, and apoptosis. This study provides a potential candidate for the treatment of hyperuricaemia and a basis for selecting therapeutic tea for patients with hyperuricaemia.

Tea Consumption is Associated with an Increased Risk of Hyperuricemia in an Occupational Population in Guangdong, China

Purpose

Chronic hyperuricemia leads to long-term deposition of monosodium urate crystals that may damage the joint structure and affect quality of life. Although hyperuricemia prevalence varies, most studies indicate increased cases of hyperuricemia worldwide. The relationship between hyperuricemia and tea consumption is uncertain. This cross-sectional study investigated the effect of tea consumption on the risk of hyperuricemia in the working population in Guangdong, China.

Patients and Methods

Data on weight, height, blood pressure, laboratory test results, and health questionnaire responses of 7644 adults aged ≥18 years were obtained from the health examinee dataset of Nanfang Hospital. The characteristics of subjects with and without hyperuricemia were compared using t-tests or non-parametric Mann–Whitney U-tests for continuous variables and chi-square tests for categorical variables. Relationships between hyperuricemia and participant characteristics (sex, age, education level, smoking history, alcohol consumption, hypertension, body mass index, tea consumption, and other dietary factors) were examined using univariate and multivariate logistic regression models to identify independent risk factors for hyperuricemia.

Results

Tea consumption was associated with a higher risk of hyperuricemia in the crude model (odds ratio [OR] 1.74, 95% confidence interval [CI] 1.48–2.05, once a month through twice a week vs never, P<0.001; OR 2.44, 95% CI 2.07–2.89, ≥3 times a week vs never, P<0.001). The adjusted OR for hyperuricemia was 1.30 (95% CI 1.08–1.56, P=0.006) in participants who consumed tea once a month through twice a week and 1.35 (95% CI 1.11–1.64, P=0.003) in those who consumed tea ≥3 times a week compared with the “never” reference group after adjusting for sociodemographic factors, anthropometric and biochemical indices, and dietary factors. This relationship remained significant in men but not women in subgroup analysis.

Conclusion

Tea consumption is an independent risk factor for hyperuricemia and is more pronounced in men than women.

Efficacy of antioxidants therapy on progression of periodontal disease - A randomized control trial

Background and Aim

Increased oxidative stress has emerged as one of the prime factors in the pathogenesis of periodontitis. Hence, antioxidant therapy may become a promising tool in the treatment of periodontal disease. Uric acid is a major salivary antioxidant, levels of which decrease in periodontitis. The aim of the present study was to investigate the effect of antioxidant therapy on the progression of periodontal disease.

Material and Methods

This is a randomized controlled clinical trial conducted among 48 systemically healthy participants having generalized gingivitis with probing depth <3 mm, plaque index (PI) <1, and no bone and attachment loss. Participants were randomly assigned equally (n = 24) into two groups (test and control) using the lottery method. Full mouth scaling and root planing were performed in both the groups and oral hygiene instructions were given. Periodontal assessment at baseline 1 h after scaling and root planing was done with clinical parameters by a single examiner. Test group was prescribed; the commercially available anti-oxidant containing natural lycopene with green tea extract. Sample collection was done for both the groups at baseline and at the 45^th day.

Results

It was observed that significantly high results were obtained during intra-group comparison for both modified plaque index and sulcus bleeding index from baseline to 45 days. After treatment, a very highly significant increase (P ≤ 0.001) in the test group and significant (P ≤ 0.05) increase in the control group were observed in salivary uric acid levels.

Conclusion

Oral lycopene and green tea extract supplementation is positively associated with salivary uric acid levels and plays an important role in the management of gingivitis.

Impact of Coffee/Green Tea/Soft Drink Consumption on the Risk of Hyperuricemia: A Cross-Sectional Study

This cross-sectional study aimed to investigate the association between hyperuricemia and the frequency of coffee, tea, and soft drink consumption, based on data from the Korean Genome and Epidemiology Study (KoGES) (2004-2016). We used the KoGES health examinee data, obtained from urban residents aged ≥ 40 years. Information on the participants' medical history, nutrition (total calorie, protein, fat, and carbohydrate intake), frequency of alcohol consumption, smoking status, household income, and frequency of coffee/green tea/soft drink intake was collected. A logistic regression model was used to analyze the data. Subgroup analyses were performed according to the participant's age and sex. Among 173,209 participants, there were 11,750 and 156,002 individuals with hyperuricemia and non-hyperuricemia controls, respectively. In an adjusted model, frequent coffee and green tea consumption did not increase the risk of hyperuricemia, compared to the "no intake" reference group. However, an adjusted odds ratio of hyperuricemia was 1.23 (95% confidence interval, 1.11-1.35, p < 0.001) for participants who reported consuming soft drinks ≥ 3 times per day, compared to the respective "no drink" reference group. Even after adjusting for nutritional and sociodemographic factors, frequent soft drink intake was associated with an increased risk of hyperuricemia. Meanwhile, neither coffee nor green tea intake was associated with an increased risk of hyperuricemia.

Tea consumption and serum uric acid levels among older adults in three large-scale population-based studies in China

Background and aims

The association between serum uric acid (SUA) and tea consumption has been studied in previous work, and there were arguments among various population group employed as well as different statistical approaches. The aim of this work is to investigate the tea effect on SUA levels among older adults by comparing three large-scale populations with both cross-sectional and longitudinal analyses.

Method

We examined the relationship between intake and SUA levels among older adults using linear regression. All the studies include the parameters SUA levels, tea intake, age, sex, education level, smoking status, alcohol drinking status, body mass index (BMI), and health history (diabetes, hypertension, and fasting plasma glucose). The cross-sectional analyses were conducted with 4579 older adults in the Weitang Geriatric Diseases Study (WGDS, ≥60 years), 2440 in the China Health and Nutrition Survey (CHNS, ≥60 years) and 1236 in the Chinese Longitudinal Healthy Longevity Survey (CLHLS, ≥62 years); and the longitudinal analyses were performed with 3870 (84.5%) in the WGDS and 420 (34.0%) in the CLHLS. Multivariable linear regression analyses were performed in both cross-sectional and longitudinal studies.

Results

Cross-sectional studies showed that tea consumers tended to have higher SUA levels than non-tea consumers in all the three datasets (P < 0.05). However, longitudinal associations of SUA levels with tea consumption had no statistical significance (P>0.05). The results of sex-stratified analyses were consistent with those of the whole datasets.

Conclusions

This work implied that any possible association between tea consumption and SUA levels could be very weak.

Acute effect of green tea catechins on uric acid metabolism after alcohol ingestion in Japanese men

INTRODUCTION/OBJECTIVES

Alcohol consumption is associated with hyperuricemia and gout. Previous studies have indicated a role for green tea catechins in uric acid (UA) metabolism. This study aimed to elucidate the acute effect of green tea catechins in terms of enhancing urinary excretion of UA and xanthine/hypoxanthine (Xa/HX; UA precursors) after alcohol ingestion.

METHODS

In a randomized crossover study, ten healthy Japanese subjects consumed test meals, including a Japanese distilled spirit (Shōchū) with water (SW) or Shōchū with catechin-rich green tea (SC), each containing 20 g of alcohol. The SC contained 617 mg of catechin in total. Serum and urine UA and Xa/HX concentrations were measured. Blood samples were collected after 2.5 h, and urine samples were collected between 0 and 5 h after consuming the test meal.

RESULTS

Urine UA and Xa/HX excretions were significantly higher in the SC group than in the SW group (UA: SW, 0.45 ± 0.08; SC, 0.52 ± 0.09; Xa/HX: SW, 0.08 ± 0.04; SC, 0.16 ± 0.05 mg/kg/h). UA clearance (C_UA) and fractional UA excretion (FE_UA) tended to increase more in the SC group than in the SW group (C_UA: SW, 7.76 ± 2.14; SC, 8.75 ± 2.23 mL/min/1.73 m²; FE_UA: SW, 6.08 ± 1.36; SC, 6.64 ± 1.42%). No significant differences in serum UA and Xa/HX concentrations were observed between two groups.

CONCLUSIONS

It was concluded that green tea catechins can enhance the excretion of UA and Xa/HX, even though alcohol is ingested.

TRIAL REGISTRATION NUMBER

UMIN000040076. Retrospectively registered 7 April 2020. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000045687 Key Points • Green tea catechins enhance the excretion of uric acid and xanthine/hypoxanthine, even when alcohol is ingested simultaneously. • In case of non-adherence of limiting alcohol intake, catechin-rich green tea may be an effective dietary component to continue dietary therapy.

Association between hyperuricemia, gout, urate lowering therapy, and osteoarthritis: A protocol for a systematic review and meta-analysis

INTRODUCTION

Osteoarthritis (OA), a chronic and degenerative joint disease characterized by articular cartilage degeneration, sclerosis of subchondral bone, and osteophyte formation, is deemed a leading cause of activity limitation and disability among the elderly people. Serum uric acid (UA) is a terminal metabolite of purine compound, while hyperuricemia (HU) and UA crystals are recognized causes of gout. Several studies have investigated the correlations between HU, gout and OA, but the findings are inconclusive. We are also concerned whether the urate lowering therapy (ULT) can become a potential treatment for OA and intend to undertake this meta-analysis to clarify the related hypotheses.

METHODS

Systematic literature search will be conducted on PubMed, Embase, and Web of Science to identify relevant studies up to February 2020 using appropriate search strategies. All citations and abstracts retrieved from literature search will be assessed by two reviewers independently. The Newcastle-Ottawa Scale or the Cochrane risk of bias assessment tool will be used as appropriate to assess the quality and the risk of bias of the included studies. The heterogeneity and the publication bias of the studies will be investigated accordingly.

RESULTS

We propose to undertake this meta-analysis as a feasible approach to clarify the associations between HU, gout or ULT, and OA.

DISCUSSIONS

This meta-analysis will help to strengthen our knowledge of the pathogenesis of OA and promote the development of preventive or treatment strategies.

REGISTRATION

PROSPERO registration number CRD42020168769.

High sugar-sweetened beverage intake frequency is associated with smoking, irregular meal intake and higher serum uric acid in Taiwanese adolescents

Types of sugar-sweetened beverages (SSB) can differ greatly between countries, with greater consumption of sweetened tea in Asia. This study aimed to understand changes in SSB consumption by adolescents in Taiwan over 18 years and their association with demographic characteristics and clinical outcome. This study used survey data from the 1993-1996 and 2010-2011 Nutrition and Health Surveys in Taiwan. Participants were high school students aged 13 to 18 years. Data were weighted and analysed using SUDAAN 11.0 and SAS 9.4. Participants were asked about intake frequencies of SSB and were grouped into four different SSB intake groups based on the combination of high or low frequency (including moderate frequency) of intake of sweetened tea and soda/sports/energy drinks. Results indicated over 99 % of teens reported having at least one SSB in the past week. Smoking status was significantly associated with SSB intake types with high tea intake (high tea and low soda (HL) group, OR 7·56, P < 0·001; high tea and high soda (HH) group, OR 9·96, P < 0·001). After adjustment for potential confounders, adolescents in the low tea and high soda (LH) group (β = 0·05, P = 0·034) had significantly higher mean serum uric acid values. In conclusion, sugary tea remains the SSB of choice for Taiwanese adolescents. Those with a frequent intake of soda/sports/energy drinks had a higher chance of being hyperuricaemic.

Dietary Antioxidant Supplements and Uric Acid in Chronic Kidney Disease: A Review

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.

Antioxidant therapy (lycopene and green tea extract) in periodontal disease: A promising paradigm

Background

Increased oxidative stress has emerged as one of the prime factors in the pathogenesis of periodontitis. Hence, antioxidant therapy may become a promising tool in the treatment of periodontal disease. Uric acid (UA) being a major antioxidant in saliva can be used as a marker to assess the total antioxidant capacity.

Aim

The aim of the study was to investigate the influence of orally administered antioxidants (lycopene and green tea extract) on periodontal health and salivary UA levels in gingivitis patients as an adjunct to scaling and root planing (SRP).

Materials and Methods

Thirty systemically healthy participants having generalized gingivitis were randomly distributed into two groups. Control group participants received full mouth oral prophylaxis, while test group participants received oral lycopene and green tea extract (CLIK^®) for 45 days along with complete oral prophylaxis. Plaque index (PI), sulcular bleeding index (SBI), and salivary UA levels were evaluated at baseline and 45 days after SRP. Data were analyzed with t-test, using SPSS software (PASW, Windows version 18.0).

Results

Both treatment groups demonstrated statistically highly significant (P ≤ 0.001) reduction in plaque and SBI. After treatment, a highly significant increase (P ≤ 0.001) in the test group and significant (P ≤ 0.05) increase in the control group was observed for salivary UA levels. Posttreatment comparison between test and control group delineated statistically significant results in PI (P ≤ 0.001), SBI (P ≤ 0.001), and salivary UA levels (P ≤ 0.01).

Conclusion

Lycopene with green tea extract may prove to be a promising adjunctive prophylactic and therapeutic modality in the treatment of gingivitis patients. However, further studies are needed to evaluate the additive effect of antioxidants with routine oral prophylaxis therapy.

Is meat consumption associated with depression? A meta-analysis of observational studies

BACKGROUND

A number of epidemiological studies have examined the effect of meat consumption on depression. However, no conclusion has been reached. The aim of this study was to examine the relationship between meat consumption and depression.

METHODS

The electronic databases of PUBMED and EMBASE were searched up to March 2017, for observational studies that examined the relationship between meat consumption and depression. The pooled odds ratio (OR) for the prevalence of depression and the relative risk (RR) for the incidence of depression, as well as their corresponding 95% confidence interval (CI), were calculated respectively (the highest versus the lowest category of meat consumption).

RESULTS

A total of eight observational studies (three cross-sectional, three cohort and two case-control studies) were included in this meta-analysis. Specifically, six studies were related to the prevalence of depression, and the overall multi-variable adjusted OR suggested no significant association between meat consumption and the prevalence of depression (OR = 0.89, 95% CI: 0.65 to 1.22; P = 0.469). In contrast, for the three studies related to the incidence of depression, the overall multi-variable adjusted RR evidenced an association between meat consumption and a moderately higher incidence of depression (RR = 1.13, 95% CI: 1.03 to 1.24; P = 0.013).

CONCLUSIONS

Meat consumption may be associated with a moderately higher risk of depression. However, it still warrants further studies to confirm such findings due to the limited number of prospective studies.