Plant-Based Diet Improves Uric Acid Levels, Gout Symptoms

A Mediterranean-inspired plant-based diet improved self-reported measures of gout as well as uric acid levels, a pilot study has found. 

There hasn’t been a lot of research on diet in gout, according to Anna Kretova, RD, who presented the study at the annual research symposium of the Gout Hyperuricemia and Crystal-Associated Disease Network. She noted that a 2019 systematic review of low-calorie diets, low-purine diets, and Mediterranean diets found that uric acid levels below 0.6 mmol/L were achieved only in those on the Mediterranean diet. A 2020 study compared a low-fat, high-carbohydrate, plant-based diet vs an animal-based, ketogenic diet in healthy individuals. After 2 weeks, uric acid levels increased in those on the animal-based, low-carb diet and decreased in those on the plant-based diet. 

Some foods are considered to be proinflammatory and generally come from animal origins, including saturated fats and animal protein in addition to ultraprocessed foods. Foods that have anti-inflammatory properties are mostly plant based and unprocessed and often rich in fiber. “From recent interventional studies, we also know that the whole- foods plant-based diet has shown to be effective as treatments of the main comorbidities of gout, such as obesity, cardiovascular disease, or [osteoarthritis],” said Kretova, who is a registered dietitian and a researcher at the Reade Rehabilitation and Rheumatology Center, Amsterdam, the Netherlands. 

Those findings led the researchers to develop a whole foods, plant-based diet and test its effect on serum uric acid in patients with gout, as well as gout disease activity and cardiovascular disease risk. Participants could not eat meat, fish, eggs, or dairy. 

The trial included 33 individuals with gout who were randomized to a 16-week intervention with five consultations with a registered dietician (n = 18) or a wait-list control group (n = 15) who received standard care. The mean age overall was 52 years, and 91% were men. The mean body mass index (BMI) was 32.6 kg/m², and the median uric acid level was 0.50 mmol/L (8.4 mg/dL).

Among gout-related outcomes, the researchers noted improvements in gout severity as measured by visual analog scale (VAS; between group difference, −2.0; P =.01), pain as measured by VAS (between group difference, −2.0; P =.04), and uric acid levels after adjustment for age, sex, and BMI (between group difference, −0.05 mmol/L, P =.004). There were also improvements in the intervention group in weight loss (between group difference, −5.3 kg; P P P = .004), and low-density lipoprotein (LDL) cholesterol (between group difference, −0.5; P = .007).

At 16 weeks, “we concluded that a Mediterranean-inspired whole foods, plant-based diet significantly lowers serum uric acid in patients with gout and abdominal obesity, and additionally, the diet reduces gout-related pain and disease activity, promotes substantial weight loss, decreases weight circumference, and improves LDL cholesterol levels, and thus decreases [cardiovascular disease] risk in these patients,” Kretova said. 

She added that some might question whether a uric acid reduction of −0.05 mmol/L is clinically relevant. “We would argue it is because of the strong decrease in disease activity and pain in the intervention group,” Kretova said. 

The study is limited by its small size, the fact that it was not blinded, and the 4-month duration, which might be too short to capture potential indirect effects of diet on hyperuricemia and chronic inflammation, Kretova said. The group is planning to follow participants out to 12 months in an extension study.

During the Q&A session after the presentation, an audience member asked if the participants were vegetarians before they entered the study, and whether the dietary change could be sustained. “It’s a very good proof-of-concept study, but whether an intervention based entirely on plant-based therapy will be something that patients will be able to adhere to long term [is uncertain],” Kretova said.

She was optimistic, even though the participants generally enjoyed food and ate a lot of red meat. “I think there will be a gradation of people who can sustain and who cannot sustain [the diet]. From what we saw, people actually found it easier to follow than they expected, and a lot of participants changed their diet permanently for the better. Not everyone became [entirely] plant-based, but they became much more plant-based than they expected from themselves. So, it is definitely feasible,” she said.

Kretova reported no relevant financial relationships. 

Jim Kling is a writer in Bellingham, Washington.