Gout: DASH Diet Lowers Serum Uric Acid

Pam Harrison

August 25, 2016

The DASH diet lowers elevated serum uric acid levels to almost the same extent as pharmacological preparations in individuals at risk for gout, a large intervention trial indicates.

"The DASH diet is a well-known diet for blood pressure, a condition common in 75% of gout patients, so we wanted to see if it could be effective for uric acid in addition to blood pressure, as using the same diet for the two conditions would be advantageous for patients with gout," Stephen Juraschek, MD, PhD, from Johns Hopkins University School of Medicine, Baltimore, Maryland, told Medscape Medical News.

"And we showed that the DASH diet can lower uric acid by 1.3 mg/dL in adults with an elevated uric acid, an effect similar to that of medication, where allopurinol, for example, the first-line urate-lowering medication, lowers uric acid by about 2 to 3 mg/dL."

The study was published online August 14 in Arthritis and Rheumatology.

DASH-sodium Trial

The DASH-sodium trial compared the effect of three different levels of sodium consumption on blood pressure in adults with either prehypertension or stage 1 hypertension.

In an ancillary analysis of the DASH-sodium trial, Dr Juraschek and colleagues analyzed the effect the same diet had on serum uric acid levels, as well as the effect varying intakes of sodium had on that same endpoint.

The DASH diet was chosen because it contains dietary constituents known to lower uric acid levels, including less consumption of red meat, which lowers purine levels, and high intake of fruits and vegetables, which increase vitamin C.

"Participants were provided all their food which included snacks and meals," the authors write.

The participants were also randomly assigned to either the DASH diet or a control diet, and during each diet, they consumed low (daily target, 60 mmol), medium (daily target, 120 mmol), or high (daily target, 180 mmol) levels of sodium for 30 days in a cross-over study design.

Dr Juraschek noted that 180 mmol/day of sodium is typical of the intake for most adults in the United States who consume 2600 calories of food per day.

The ancillary study of the DASH-sodium trial was limited to subjects who had been recruited at the Johns Hopkins University clinical center in Baltimore for the larger study. The mean age of participants was 51.5 years, and the mean serum uric acid level at baseline was 5.0 mg/dL. However, 8% of the study group had a serum uric acid level of 7 mg/dL or higher at baseline.

Uric Acid and Sodium

When the researchers analyzed outcomes in the entire study population, regardless of baseline uric acid level, they found that serum uric acid fell with an increase from low to medium sodium intake. However, no such drop in uric acid levels occurred with the switch from medium to high sodium intake, regardless of diet (control or DASH).

Table. Within-Person Change From Baseline in Uric Acid by Diet and Sodium Intake

  Baseline Mean Uric Acid Low Sodium Intake (Difference From Baseline) Medium Sodium Intake (Difference From Baseline) High Sodium Intake (Difference From Baseline)
CONTROL diet 5.0 mg/dL 0.4 mg/dL (P < .001) 0.1 mg/dL (NS) −0.1 mg/dL (NS)
DASH diet 4.9 mg/dL 0.0 mg/dL (NS) −0.4 mg/dL (P = .04) −0.3 mg/dL (P = .01)

When the investigators examined the benefit of the DASH diet vs the control diet at each sodium level, they found the DASH diet led to lower serum uric acid levels, regardless of sodium intake. Specifically, during low sodium intake, the DASH diet resulted in a significant 0.53 mg/dL reduction in serum uric acid compared with the control diet (P = .03). The difference at medium sodium intake was a significant 0.56 mg/dL reduction in serum uric acid level (P = .03); the difference at high sodium showed the same trend, but did not reach statistical significance (−0.33 mg/dL; P = .18).

The benefit of the DASH diet was even more apparent when the investigators restricted their analysis to individuals who had elevated serum uric acid at baseline. "[W]hen baseline SUA was 5 to <6 mg/dL, the DASH diet reduced [serum uric acid] by −0.45 mg/dL. This effect was incrementally greater at −0.76 mg/dL in participants with a baseline [serum uric acid] of 6 to <7 mg/dL, and −1.29 mg/dL in participants with a baseline [serum uric acid] ≥7 mg/dL (P-interaction=0.04)," the authors write.

However, as Dr Juraschek emphasized, among participants on the DASH diet, reducing sodium intake from medium to low increased uric acid levels, but increasing sodium intake from medium to high did not decrease uric acid levels.

"Thus, our study does not support the idea that people should consume excessive amounts of sodium to lower uric acid levels," he stressed, adding that excessive sodium intake can have harmful consequences on other aspects of health, such as blood pressure.

In contrast, sudden increases or decreases in uric acid can each trigger gout flares, he added, so knowing that sudden changes in sodium can cause uric acid levels to fluctuate can help physicians better counsel patients about the potential dietary causes of gout flares.

"Based on our study, physicians can definitively recommend the DASH diet to lower uric acid levels, particularly in patients with hyperuricemia," Dr Juraschek said.

"Whether or not the DASH diet prevents gout has yet to be directly shown, but this would be a logical extension of our study," he added.

"We hope to evaluate this hypothesis in future research."

Prevent Initial Gout

Asked by Medscape Medical News to comment on the study, Alan Baer, MD, associate professor of medicine, Johns Hopkins University School of Medicine, who was not involved in the study, felt that the benefit the study offers is that it suggests people could use the DASH diet to prevent the ultimate development of gout.

"Certainly there is a large group of people in the population who have elevated uric acid levels, and up to 20% or more of them are at risk for developing gout, so that is the population in whom such a diet could be very helpful," Dr Baer said.

However, despite patients often expressing a desire to manage their gout with lifestyle interventions, "once a patient has had more than two attacks of gout a year or if the disease has been present long enough to form tophi, then there is clear need to be on medication," he added.

"So the diet might help for other reasons, but once someone has had repeated attacks of gout, then adherence to a diet such as the DASH diet is not sufficient to banish the gout."

The authors and Dr Baer have disclosed no relevant financial relationships.

Arthritis Rheumatol. Published online August 14, 2016. Abstract

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