Effects of the Dietary Approaches to Stop Hypertension (DASH) Diet and Sodium Intake on Serum Uric Acid

Abstract

Objective: Randomized trial data guiding dietary recommendations to lower serum uric acid (UA), the etiologic precursor of gout, are scarce. We undertook this study to examine the effects of the Dietary Approaches to Stop Hypertension (DASH) diet (a well-established diet that lowers blood pressure) and levels of sodium intake on serum UA.

Methods: We conducted an ancillary study of a randomized, crossover feeding trial in 103 adults with prehypertension or stage I hypertension. Participants were randomly assigned to receive either the DASH diet or a control diet (typical of the average American diet) and were further fed low, medium, and high levels of sodium for 30 days, each in random order. Body weight was kept constant. Serum UA levels were measured at baseline and following each feeding period.

Results: Trial participants were 55% women and 75% black with a mean ± SD age of 51.5 ± 9.7 years and a mean ± SD serum UA level of 5.0 ± 1.3 mg/dl. The DASH diet reduced serum UA (-0.35 mg/dl [95% confidence interval (95% CI) -0.65, -0.05], P = 0.02), with a higher effect (-1.29 mg/dl [95% CI -2.50, -0.08]) among participants (n = 8) with a baseline serum UA level of ≥7 mg/dl. Increasing sodium intake from the low level decreased serum UA during the medium sodium intake period (-0.3 mg/dl [95% CI -0.5, -0.2], P < 0.001) and during the high sodium intake period (-0.4 mg/dl [95% CI -0.6, -0.3], P < 0.001).

Conclusion: The DASH diet lowered serum UA, and this effect was greater among participants with hyperuricemia. Moreover, we found that higher sodium intake decreased serum UA, which enhances our knowledge of urate pathophysiology and risk factors for hyperuricemia.

Trial registration: ClinicalTrials.gov NCT00000608.

Conflict of interest statement

Conflicts of interest

The authors have no conflicts of interest to report.

© 2016, American College of Rheumatology.

Figures

Figure 1

Comparison of uric acid levels at baseline, the end of the low sodium feeding period, the end of the medium sodium feeding period, and the end of the high sodium feeding period for either the control (diamonds, blue) versus DASH (circles, green) diets. Vertical dashed lines represent differences at each of the sodium intake levels with P-values determined via t-tests). Horizontal lines represent differences between sodium intake levels (low versus baseline, medium versus low, high versus medium, and high versus low) determined using generalized estimating equations.

Figure 2

Forest plots of the effects of (A) DASH versus Control diets and (B) high (180 mmol/d) versus low (60 mmol/d) sodium intake on uric acid (mg/dL, 95% CI) in subgroups of sex, race, baseline uric acid, baseline body mass index, and baseline high blood pressure (systolic blood pressure ≥ 140 mm Hg or diastolic blood pressure ≥ 90 mm Hg). Given that there was no salt-diet interaction, the comparison of DASH versus control diets utilized all three serum uric acid measures determined after each of the sodium feeding periods. Meanwhile the high versus low sodium comparison is presented in participants consuming either the control or DASH diet.