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Increased Dietary Vitamin C Intake May Help Reduce Gout Risk, Study Finds

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The analysis of NHANES data revealed an inverse association between dietary vitamin C intake and gout risk.

New research is calling attention to an inverse association between dietary vitamin C intake and the risk of developing gout.1

The analysis of data from more than 10,000 National Health and Nutrition Examination Survey (NHANES) 2013-2018 participants revealed a reduced risk of gout among those who reported consuming greater quantities of dietary vitamin C. Results also pointed to a reduced risk of hyperuricemia with increased vitamin C intake.1

Gout is the most common type of inflammatory arthropathy in adults, affecting an estimated 3.9% of adults in the US. Although its etiology is multifaceted and involves genetics, diet, and lifestyle, high serum uric acid is a key risk factor for gout. The antioxidant properties of vitamin C have led to speculation that it may indirectly reduce uric acid production.1,2

“Currently, evidence regarding the association between dietary vitamin C levels and gout is insufficient,” Shengguang Li, of the department of rheumatology and immunology at Peking University International Hospital in China, and colleagues wrote.1

To fill this gap in research, investigators assessed cross-sectional data on gout, dietary vitamin C intake, and other variables from individuals > 20 years of age who participated in NHANES 2013-2018. Pregnant females or those with missing data on gout, dietary vitamin C intake, or covariates were excluded from the analysis.1

Vitamin C intake from the first survey in the NHANES database was measured through a 24-hour dietary recall during an interview using the automated multiple-pass method to collect detailed information about all foods and beverages consumed in the previous 24 hours. Nutrient content, including vitamin C, was calculated using the food composition database.1

Vitamin C intake from the second survey was measured through a second 24-hour dietary recall conducted via telephone a few days after the initial interview. The same automated multiple-pass method was used to collect detailed dietary information about the participants’ consumption over the previous 24 hours, and vitamin C content was calculated using the same food composition database, measuring vitamin C intake from a different time point to account for day-to-day variability in the participant’s diet.1

Participants were categorized into 4 quartiles based on their calculated dietary vitamin C intake:

  • Q1 (≤19.9 mg/day)
  • Q2 (19.9-49.7 mg/day)
  • Q3 (49.7–110.375 mg/day)
  • Q4 (≥110.375 mg/day)

Gout was defined as a positive answer to the question “Has a doctor or other health professional ever informed you that you had gout?”. Serum uric acid (SUA) concentration was measured at the NHANES Laboratory for all 3 cycles, and hyperuricemia was defined as an SUA concentration >6mg/dL.1

In total, 12,589 participants from the NHANES 2013-2018 were included in the present analysis, 652 (5%) of whom experienced gout. The average age was 49.9 ± 17.5 years and 50.7% of participants were female. There were 3177 participants in Q1, 3142 in Q2, 3148 in Q3, and 3122 in Q4.1

Investigators pointed out a significant difference in age across quartiles (P <.001). Specifically, age increased from 48.3 ± 17.3 years in Q1 to 50.3 ± 17.6 years in Q4. The sex distribution also varied, with males comprising 48.9% of Q1 and 53% of Q4 (P <.001).1

Results showed the prevalence of gout decreased across quartiles, with Q1 showing the highest percentage at 5.40% (n = 169) and Q4 showing the lowest at 4.60% (n = 142). After adjusting for other risk factors, investigators observed a significant correlation between vitamin C intake and gout (odds ratio [OR], 0.88; 95% CI, 0.79–0.97; P = .015). Additionally, when dietary vitamin C consumption was analyzed using quartiles, there was a significant inverse association between dietary vitamin C and gout after adjusting for potential confounders.1

Compared with individuals with lower vitamin C consumption in Q1, the adjusted OR values for dietary vitamin C intake and gout were 0.87 (95% CI, 0.69–1.1; P = .237) in Q2, 0.81 (95% CI, 0.64–1.02; P = .076) in Q3, and 0.77 (95% CI, 0.6–0.99; P = .042) in Q4. Subgroup analyses revealed significant interactions between vitamin C levels and gout, notably influenced by sex. Investigators observed a similar inverse association between vitamin C intake and gout when they used data on dietary vitamin C from the second survey, even after adjusting for all covariates (OR, 0.81; 95% CI, 0.72–0.91; P <.001).1

Vitamin C was also negatively associated with hyperuricemia (OR, 0.94; 95% CI, 0.9–0.98; P = .005). Compared with Q1, the adjusted OR values for dietary vitamin C from the first survey and hyperuricemia were 0.77 (95% CI, 0.69–0.86; P = .65) for Q2, 0.81 (95% CI, 0.72–0.91; P = .014) for Q3, and 0.72 (95% CI, 0.64–0.81; P <.001) for Q4.1

Investigators acknowledged multiple limitations to these findings, including the cross-sectional study design; the inability to establish causality between vitamin C intake and gout; the potential lack of generalizability to other populations due to dietary differences; residual confounding; and recall bias for vitamin C intake.1

“There is a negative association between dietary vitamin C intake and gout prevalence among adults in the United States,” investigators concluded.1 “The results of this study highlight the association between dietary vitamin C intake and gout.”

References

  1. Zou Y, Liu Y, Li S, et al. Association between dietary vitamin C intake and gout among American adults. Front. Immunol. https://doi.org/10.3389/fimmu.2024.1431323
  2. National Kidney Foundation. Quick Facts: Gout and Chronic Kidney Disease. Accessed October 11, 2024. https://www.kidney.org/kidney-topics/quick-facts-gout-and-chronic-kidney-disease

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