Associations Between Composite Dietary Antioxidant Index and Gout: National Health and Nutrition Examination Survey 2007-2018

Introduction: To explore the relationship between the composite dietary antioxidant index (CDAI) and gout to provide support for preventing gout through dietary intervention. Methods: Eligible participants from the 2007 to 2018 National Health and Nutrition Examination Survey aged 20 years and older were included in this cross-sectional study. The weighted chi-square test was used to compare the categorical variables difference between CDAI quartiles groups. The weighted univariate and binary logistic regression analysis were used to test the association between variables and gout. The weighted multivariable logistic regression was used to test the association of CDAI and gout in 4 different models. Subgroup analysis on the associations of CDAI with gout was conducted with stratified factors. Results: The final participants were 26,117, 13,103 (50.17%) were female, 8718 (33.38%) were 40-59 years, 11,200 (42.88%) were white and 1232 (4.72%) had gout. After adjusting for all covariates, the CDAI was associated with gout (odds ratio (OR), .97; 95% CI: .95-1.00). Participants in the highest CDAI quantile group were at low risk of gout (odds ratio (OR), .65; 95% CI: .50-.84) versus those in the lowest quantile group. Subgroup analysis and interaction test showed no significant dependence on diabetes mellitus (DM), marital status, alcohol status, hypertension, poverty income ratio (PIR), education level, body mass index (BMI), smoke status, age, sex, race, and chronic kidney disease (CKD) on this association (all p for interaction >.05). Conclusions: Composite dietary antioxidant index was inversely associated with gout in US adults, and dietary antioxidant intervention might be a promising method in the therapy of gout and greater emphasis should be placed on zinc, selenium, carotenoids, vitamins A, C, and E.

A cross-sectional study on the association between dietary inflammatory index and hyperuricemia based on NHANES 2005-2018

Background

Hyperuricemia is a common condition that can lead to gout and other related diseases. It has been suggested that Inflammatory factors play important role in the development and progression of hyperuricemia. The dietary inflammatory index (DII) enables the assessment of the inflammatory potential of an individual's diet. This study aimed to investigate the association between DII and hyperuricemia.

Methods

This study was performed based on a cross-sectional dataset from the National Health and Nutrition Examination Survey (NHANES) 2005-2018. Participants aged 18 years and above with dietary intake and serum uric acid level information were included. DII scores were calculated using dietary intake data, based on which participants were categorized into tertiles. Multivariable logistic regression analysis was adopted to investigate the association between DII and hyperuricemia.

Results

Among a total of 31,781 participants in the analysis, 5,491 had hyperuricemia. After adjusting confounding factors, the odds of hyperuricemia are significantly higher in the second (OR 1.17, 95% CI 1.07-1.29) and third tertiles (OR 1.31, 95% CI 1.19-1.44) relative to the first one.

Conclusion

This study suggested that diet with higher inflammatory potential, as measured by DII, is associated with increased hyperuricemia risk. These findings indicated that dietary modification may be a potential approach for hyperuricemia's prevention and control.

Vitamin E supplementation in the treatment on nonalcoholic fatty liver disease (NAFLD): Evidence from an umbrella review of meta-analysis on randomized controlled trials

OBJECTIVE

We conducted this umbrella review of meta-analysis on randomized controlled trials to clarify the effects of vitamin E administration on alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), degrees of steatosis and fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

PubMed, MEDLINE, SCOPUS, EMBASE, and Web of Science were searched to identify pertinent articles published up to June 2023. To calculate the overall effect size (ES) and confidence intervals (CI), random-effects model was used.

RESULTS

Six meta-analyses were included in the umbrella review. By pooling ES based on the random-effects model, we found that vitamin E supplementation significantly decreased ALT (ES -6.47, 95% CI -11.73 to -1.22, P = 0.01), AST (ES -5.35, 95% CI -9.78 to -0.93, P = 0.01), degrees of fibrosis (ES -0.24, 95% CI -0.36 to -0.12, P < 0.001) and steatosis (ES -0.67, 95% CI -0.88 to -0.45, P < 0.001) in NAFLD patients, but had no effect on GGT. In the subgroup analyses, we detected that fibrosis scores notably decreased when vitamin E dosage was >600 IU/day (ES -0.25, 95% CI -0.41 to -0.10, P = 0.002) and when the treatment duration was ≥12 months (ES -0.24, 95% CI -0.37 to -0.12, P < 0.001).

CONCLUSION

Vitamin E administration improves ALT, AST, fibrosis, and steatosis in NAFLD subjects. Fibrosis scores were significantly reduced when vitamin E dosage exceeded 600 IU/day or with a treatment duration of at least 12 months.

Effects of vitamin C supplementation on gout risk: results from the Physicians' Health Study II trial

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).

Dietary Vitamin E Intake Was Inversely Associated with Hyperuricemia in US Adults: NHANES 2009-2014

INTRODUCTION

Current evidence on the association between dietary vitamin E intake and hyperuricemia risk is limited and conflicting.

OBJECTIVE

The aim of the study was to assess the association of dietary vitamin E intake with hyperuricemia in US adults.

METHODS

We conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey, 2009-2014. Dietary vitamin E intake was evaluated through two 24-h dietary recall interviews. Logistic regression and restricted cubic spline models were used to examine the association between dietary vitamin E intake and hyperuricemia.

RESULTS

Overall, 12,869 participants were included. The prevalence of hyperuricemia was 19.35%. After adjustment for age, gender, BMI, race, educational level, smoking status, alcohol consumption, physical activity, total daily energy intake, total cholesterol, protein intake, glomerular filtration rate, serum Cr, use of uric acid drugs, and drug abuse, the odds ratio (95% confidence interval) of hyperuricemia for the highest tertile of dietary vitamin E intake was 0.77 (0.63-0.96) compared with that of the lowest tertile. In men, dietary vitamin E intake and hyperuricemia were negatively correlated. In stratified analyses by age (20-39, 40-59, and ≥60 years), dietary vitamin E intake was inversely associated with hyperuricemia only among participants aged ≥60 years. Dose-response analyses showed that dietary vitamin E intake was inversely associated with hyperuricemia in a nonlinear manner.

CONCLUSION

Dietary vitamin E intake was negatively correlated with hyperuricemia in US adults, especially among males and participants aged ≥60 years.

Associations of Serum Retinol and α-Tocopherol Levels with Uric Acid Concentrations: Analysis of a Population-Based, Nationally Representative Sample

The effects of serum retinol and α-tocopherol on serum uric acid levels have not been established, especially in Asian people. This study evaluated the independent associations of retinol and α-tocopherol with serum uric acid levels in the Korean population. We included 6023 participants aged ≥ 19 years from the Korean National Health and Nutrition Examination Survey (KNHANES). Serum retinol and α-tocopherol levels were divided into quintiles, and a multivariate linear regression model was used to evaluate the association of serum retinol and α-tocopherol levels with uric acid concentration. Additionally, we used multivariate logistic regression to examine the relationships between the levels of these micronutrients and hyperuricemia. Serum retinol levels were positively associated with uric acid concentrations in a dose-dependent fashion in both sexes (p_trend < 0.001); the difference in serum uric acid levels between the highest and lowest quintiles of retinol levels was 0.57 mg/dL in men and 0.54 mg/dL in women. In the multivariable logistic model, the hyperuricemia risk increased linearly with the increase in serum retinol level, regardless of sex (p_trend < 0.001). Although the serum α-tocopherol level appeared to be significantly associated with increased uric acid levels, this association was nullified after adjusting for serum retinol levels. Serum retinol levels were positively associated with serum uric acid levels and hyperuricemia in a dose-response fashion. Maintaining serum retinol concentrations under sub-toxic levels might be necessary to prevent hyperuricemia-related adverse health outcomes.

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.

Effect of Oral Vitamin C Supplementation on High-Altitude Hyperuricemia in Young Men Initially Migrating to High Altitude: A Pilot Study

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.