The Diet Gout Trial

The public health burden of gout is substantial. Several lines of evidence suggest that a DASH diet might lower uric acid. However, there are no trials of the DASH diet in adults with gout. This trial is a cross-over study of the effects of a DASH-like diet on uric acid in adults with gout and hyperuricemia, who are not taking urate-lowering therapy.

Perpetuated by the "Western" lifestyle and resulting obesity epidemic, the prevalence of gout has increased over the past few decades to 3.9% of US adults (8.3 million individuals). This prevalence increases with age to 9.3% of US adults over 60 years (4.7 million).

Participants will be community-dwelling adults, aged 18+ with a baseline serum uric acid level of 7 mg/dL, who have a self-reported history of gout and are not taking urate lowering medications (e.g. allopurinol, febuxostat, probenecid).

This trial is comprised of two study periods: (1) a dietitian-directed diet (DD) or (2) self-directed usual diet (SD). Each period lasts 4 weeks. All participants will participate in both periods, but half will undergo the dietitian-directed diet first while the other half will undergo the self-directed diet first. During the dietitian-directed diet, participants will receive $105/week of foods in a pattern that conforms to the DASH diet. The DASH diet emphasizes fruit, vegetables, lean meat, low fat dairy, and high fiber, while restricting red meat, sweets, and sugary beverages. During the self-directed diet, participants will be asked to eat their typical diet outside of the study. Investigators anticipate 40 participants in this study.

The primary outcome is uric acid. Secondary outcomes of this study include: body mass index, systolic and diastolic blood pressure, fasting cholesterol, and fasting blood glucose. Both primary and secondary outcomes will be measured 3 times: (1) before the study begins (baseline), (2) after period 1 (at 4 weeks), and (3) after period 2 (at 8 weeks). Patient-reported outcomes, dietary compliance, and urine electrolytes will be assessed throughout the study as well.

The primary comparison will be serum uric acid concentrations measured after the 4-week dietitian-directed diet versus uric acid concentrations measured after the 4-week self-directed diet (DD vs. SD). Comparisons will be made within person using generalized estimating equations (GEE) with and without adjustment for baseline uric acid concentration. Investigators will use GEE models for secondary outcomes as well.

Inclusion criteria

Age > 18-100 years

Self-reported gout diagnosis

Serum Uric Acid > 7 mg/dL

Exclusion criteria

Recent or planned changes to urate lowering therapies (e.g. allopurinol, febuxostat, probenecid)

Recent or planned changes to hypertension, lipid, or diabetes medications

Patients with hyperkalemia (>5 mmol/L)

Chronic kidney disease (GFR < 30 cc/min), kidney transplant, dialysis

Gastro-intestinal conditions (e.g. history of gastric bypass surgery, active inflammatory bowel disease, malabsorption, or major GI resection)

Active cancer treatment (e.g. radiation or chemotherapy)

Diagnosis of any of the following in the past 6 months: heart attack, heart failure, angina, coronary bypass or angioplasty, or Chronic Obstructive Pulmonary Disease (COPD)

Alcohol use over 14 drinks per week

Inability to give informed consent

Active use of warfarin, insulin, or chronic steroids (like prednisone)

Terminal or mental illness