DASH diet reduces serum urate, especially in those with hyperuricemia
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The Dietary Approaches to Stop Hypertension — or DASH — diet successfully reduces serum urate, particularly among those with hyperuricemia, according to data published in Arthritis & Rheumatology.
“The link between diet and gout has been described since antiquity,” Stephen P. Juraschek, MD, PhD, of Beth Israel Deaconess Medical Center, Harvard Medical School, told Healio Rheumatology. “However, the ideal dietary pattern for adults with gout is unclear. Traditionally, a low purine diet has been the focus for gout prevention, but this diet is not palatable and may involve foods that are detrimental to cardiovascular health. Meanwhile, 75% of adults with gout also have hypertension.”
“The DASH diet is proven to lower blood pressure in adults with elevated blood pressure or hypertension,” he added. “It also reduces LDL-cholesterol — the cholesterol associated with heart attacks — which is also elevated in adults with gout.”
To examine whether the DASH diet lowers serum urate, compared to an alternative diet that simply emphasizes high-fiber fruits and vegetables, Juraschek and colleagues conducted a secondary study of the DASH trial. According to the researchers, this 8-week, parallel-arm study randomized 459 adults with a systolic blood pressure of less than 160 mmHg, and a diastolic blood pressure of 80‐95 mmHg, into one of three feeding groups.
Between September 1994 and March 1996, participants — none of whom were using blood pressure medications — received either a typical American diet, used as the control; a diet that was high in fruits and vegetables but otherwise similar to the control; or the DASH diet, which emphasizes fruits, vegetables and low‐fat dairy products, as well as reduced fat, saturated fat and cholesterol overall. BMI was kept constant throughout the trial, with serum urate assessed at baseline and after 8 weeks.
A typical American diet was defined as potassium, magnesium and calcium levels matching the 25th percentile of U.S. consumption, and macronutrient profiles and fiber reflecting the average intake levels in the United States.
For their own study, Juraschek and colleagues in 2018 measured serum levels from available stored specimens from three of the four participating clinical centers. Specimens were collected from a total of 327 participants with available baseline and week-8 data, including 110 in the DASH group, 110 who received the fruits-and-vegetables diet, and 107 in the control group. Among these participants, the mean baseline serum urate was 5.7±1.5 mg/dL.
According to the researchers, the DASH diet reduced serum urate by 0.25 mg/dL (95% CI, –0.43 to –0.08), compared with the control group. In the fruit-and-vegetables group, serum urate was reduced by 0.17 mg/dL (95% CI, –0.34 to 0), compared with a typical American diet. These effects increased with higher baseline serum urate levels in the DASH group (P = 0.04), but not in the fruits-and-vegetables group.
“Our study shows that the DASH diet reduces urate, the most important risk factor for gout targeted by most gout drugs,” Juraschek said. “This reduction is great news as DASH also lowers blood pressure and cholesterol, potentially addressing three problems with a single strategy. Moreover, adults with higher urate level saw even greater reductions from the DASH diet in our study. We hope our study continues to highlight the importance of healthy diet, specifically the DASH diet, as a strategy for greater health among adults with gout.”
Perspective
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There remains some controversy with regard to dietary restrictions in patients with gout. Associations with shellfish, organ meat and alcohol have clearly been proven. But, a uric acid free diet lowers the serum uric acid level only about 1 mg/dL and is not palatable; therefore, it is often associated with poor compliance.
The present study by Juraschek and colleagues examined specimens from 459 adults using specimens from an old study from the 1990s that examined blood pressure and cholesterol with various dietary changes. The DASH diet is high in fruits, vegetables and reduced-fat dairy products as well as other low-fat foods. It did its original job of showing a reduction of BP and cholesterol levels. After 8 weeks, there was a small but significant decrease in serum uric acid (0.25 mg/dL). The change was greater in those with higher baseline uric acid levels.
There may be useful information here but it’s not new. The same author published a previous study in 2016 showing similar results in 103 adults. The expansion of samples studied did increase (103 to 459) which is probably the story here. But, do these small changes in uric acid levels result in a lower incidence of clinical gout? These studies don’t answer this more important question.
Fortunately, we do have another study from Rai and colleagues published in BMJ in 2017 that looked at patients on this same diet and found a relative risk (RR) of 0.68 for developing gout. In contrast, a higher fat Western diet carried a RR of 1.42. This last study takes data from the lab and applies it to what really matters: incidence of gout. Still, we do applaud Juraschek for expanding the number of samples studied from 103 to 459 in this follow-up study; now all we have to do is convince our patients that diet matters!
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