Effects of dietary macronutrients on serum urate: results from the OmniHeart trial.

Background Dietary recommendations to prevent gout emphasize a low-purine diet. Recent evidence suggests that the Dietary Approaches to Stop Hypertension (DASH) diet reduces serum urate while also improving blood pressure and lipids. Objective To compare the effects of DASH-style diets emphasizing different macronutrient proportions on serum urate reduction. Methods We conducted a secondary analysis of the Optimal Macronutrient Intake Trial to Prevent Heart Disease feeding study, a 3-period, crossover design, randomized trial of adults with prehypertension or hypertension. Participants were provided with 3 DASH-style diets in random order, each for 6 wk. Each DASH-style diet emphasized different macronutrient proportions: a carbohydrate-rich (CARB) diet, a protein-rich (PROT) diet, and an unsaturated fat-rich (UNSAT) diet. In the PROT diet, approximately half of the protein came from plant sources. We compared the effects of these diets on serum urate at weeks 4 and 6 of each feeding period. Results Of the 163 individuals included in the final analysis, the mean serum urate at baseline was 5.1 mg/dL. Only the PROT diet reduced serum urate from baseline at the end of the 6-wk feeding period (-0.16 mg/dL; 95% CI: -0.28, -0.04; P = 0.007). Neither the CARB diet (-0.03 mg/dL; 95% CI: -0.14, 0.09; P = 0.66) nor the UNSAT diet (-0.01 mg/dL; 95% CI: -0.12, 0.09; P = 0.78) reduced serum urate from baseline. The PROT diet lowered serum urate by 0.12 mg/dL (95% CI: -0.20, -0.03; P = 0.006) compared with CARB and by 0.12 mg/dL (95% CI: -0.20, -0.05; P = 0.002) compared with UNSAT. Conclusions A DASH-style diet emphasizing plant-based protein lowered serum urate compared with those emphasizing carbohydrates or unsaturated fat. Future trials should test the ability of a DASH-style diet emphasizing plant-based protein to lower serum urate and prevent gout flares in patients with gout. This trial was registered at clinicaltrials.gov as NCT00051350.