Effects of Dietary Patterns on Serum Urate: Results From a Randomized Trial of the Effects of Diet on Hypertension

Abstract

Objective: To determine whether the Dietary Approaches to Stop Hypertension (DASH) diet or an alternative, simplified diet, emphasizing high-fiber fruits and vegetables (the FV diet), lowers serum urate levels.

Methods: We conducted a secondary study of the DASH feeding study, a 3-arm, parallel-design, randomized trial of 459 adults with systolic blood pressure (BP) of <160 mm Hg and diastolic BP of 80-95 mm Hg, who were not receiving BP medications. Participants were randomized to receive 8 weeks of monitored feeding and ate 1 of 3 diets: 1) a typical American diet (control), 2) the FV diet, a diet rich in fruits and vegetables but otherwise similar to the control diet, or 3) the DASH diet, which was rich in fruits, vegetables, and low-fat dairy products, and reduced in fat, saturated fat, and cholesterol. Body weight was kept constant throughout the study. Serum urate levels were measured at baseline and after 8 weeks of feeding.

Results: For the 327 participants with available specimens (mean ± SD age 45.4 ± 11.0 years, 47% women, 50% African American), the mean ± SD baseline serum urate level was 5.7 ± 1.5 mg/dl. Compared to the control diet, the FV diet reduced the mean serum urate level by 0.17 mg/dl (95% confidence interval [95% CI] -0.34, 0.00; P = 0.051) and the DASH diet reduced the mean serum urate level by 0.25 mg/dl (95% CI -0.43, -0.08; P = 0.004). These effects increased with increasing baseline serum urate levels (<5, 5-5.9, 6-6.9, 7-7.9, and ≥8 mg/dl) for those receiving the DASH diet (a reduction of 0.08, 0.12, 0.42, 0.44, and 0.73 mg/dl, respectively; P for trend = 0.04), but not for those receiving the FV diet.

Conclusion: Our findings indicate that the DASH diet reduces serum urate levels, particularly among those with hyperuricemia. These findings support the growing need for a dedicated trial to test the DASH diet among patients with hyperuricemia and gout.

Trial registration: ClinicalTrials.gov NCT00000544.

Figure 1.

Mean difference in serum urate (mg/dL) between diets, comparing the fruit and vegetables diet versus control diet, the DASH (Combination) diet versus the control diet, and the DASH (Combination) diet versus the fruit and vegetables diet. All comparisons represent the difference in week 8 measurements adjusted for baseline measurements.

Figure 2.

Mean difference in serum urate (mg/dL) between diets, comparing (A) the fruit and vegetables diet versus control diet and (B) the DASH (Combination) diet versus the control diet in strata of demographic groups and relevant comorbidities. All comparisons represent the difference in week 8 measurements adjusted for baseline measurements. Note that baseline hyperuricemia is defined as a baseline serum urate > 6 mg/dL for women or > 7 mg/dL for men.