Vitamin C intake and serum uric acid concentration in men

Abstract

Objective: We examined associations between vitamin C intake and serum uric acid in men in a population-based study.

Methods: We included 1387 men without hypertension and with body mass index (BMI) < 30 kg/m(2) in the Health Professional Follow-up Study. Dietary intake was assessed with a semiquantitative food frequency questionnaire validated for use in this population. Serum uric acid concentrations were measured.

Results: Greater intakes of total vitamin C were significantly associated with lower serum uric acid concentrations, after adjustment for smoking, BMI, ethnicity, blood pressure, presence of gout, use of aspirin, and intake of energy, alcohol, dairy protein, fructose, meat, seafood and coffee. An inverse dose-response association was observed through vitamin C intake of 400-500 mg/day, and then reached a plateau. Adjusted mean uric acid concentrations across total vitamin C intake categories (< 90, 90-249, 250-499, 500-999, or > or = 1000 mg/day) were 6.4, 6.1, 6.0, 5.7, and 5.7 mg/dl, respectively (p for trend < 0.001). Greater vitamin C intake was associated with lower prevalence of hyperuricemia (serum uric acid > 6 mg/dl). Multivariate odds ratios for hyperuricemia across total vitamin C intake categories were 1 (reference), 0.58, 0.57, 0.38, and 0.34 (95% CI 0.20-0.58; P for trend < 0.001). When we used dietary data, which were assessed 4-8 years before blood collection, as predictors, we observed similar inverse associations between vitamin C intake and uric acid.

Conclusion: These population-based data indicate that vitamin C intake in men is inversely associated with serum uric acid concentrations. These findings support a potential role of vitamin C in the prevention of hyperuricemia and gout.

Figure 1. Odds Ratio and 95% confidence interval of hyperuricemia (serum uric acid > 360 μmol/L) according to total vitamin C intake category

Panel A was calculated by a logistic regression model with the lowest intake category (<90 mg/d) as the reference group; Panel B was fitted by a cubic Spline logistic model with 90 mg/d as the reference group and the 95% confidence intervals are indicated by the dashed lines. Both models were adjusted for age (y), smoking status (never smoker, past smoker, or current smoker: 1–14 or ≥ 15 cigarettes/d), BMI (<23, 23–24.9, 25–26.9, 27–28.9, or ≥29 kg/m²), ethnicity (Caucasian vs. others), systolic blood pressure (<105, 105–114, 115–124, or ≥125 mm Hg), presence of gout (yes/no), use of aspirin (yes/no), total energy (kcal/d), dairy protein (g/d), fructose (g/d), alcohol (0, <5, 5–9, 10–14, 15–29, 30–49, or ≥ 50 g/d), and coffee (0, <1, 1–3, 4–5, or ≥ 6 cups/d).

Figure 1. Odds Ratio and 95% confidence interval of hyperuricemia (serum uric acid > 360 μmol/L) according to total vitamin C intake category

Panel A was calculated by a logistic regression model with the lowest intake category (<90 mg/d) as the reference group; Panel B was fitted by a cubic Spline logistic model with 90 mg/d as the reference group and the 95% confidence intervals are indicated by the dashed lines. Both models were adjusted for age (y), smoking status (never smoker, past smoker, or current smoker: 1–14 or ≥ 15 cigarettes/d), BMI (<23, 23–24.9, 25–26.9, 27–28.9, or ≥29 kg/m²), ethnicity (Caucasian vs. others), systolic blood pressure (<105, 105–114, 115–124, or ≥125 mm Hg), presence of gout (yes/no), use of aspirin (yes/no), total energy (kcal/d), dairy protein (g/d), fructose (g/d), alcohol (0, <5, 5–9, 10–14, 15–29, 30–49, or ≥ 50 g/d), and coffee (0, <1, 1–3, 4–5, or ≥ 6 cups/d).