Houston rheumatologist Nilanjana Bose, MD, MBA, has no doubt that patients can reduce symptoms of rheumatoid arthritis (RA) by eating healthier.

“It’s not like they get better just because they change their diet. But I see a lot of patients who reduce or give up red meat, sugars, and processed foods, and they start feeling a lot better, a lot healthier, less inflamed,” she said. “Coupled with the right medications, it really helps their treatment get a jump start.”

The American College of Rheumatology (ACR) agrees that nutrition is a key component of RA relief. But, as the college acknowledges, high-quality evidence of a connection between better diet and improved RA symptoms has been elusive.

While the ACR conditionally recommends a Mediterranean-style diet over no specified diet in its 2022 guideline, the college says there’s only “low-to-moderate” evidence to support this.

And a systematic review and meta-analysis published in September 2025 found no improvement in disease activity or physical function in patients with RA who followed vegetarian or vegan diets, although pain levels fell slightly.

“There’s a lack of high-quality, randomized controlled trials that have really delved deeper in into plant-based and plant-predominant diets,” said Tamiko Robin Katsumoto, MD, a clinical associate professor of rheumatology and immunology at Stanford University in Stanford, California.

Still, she said, research points in one direction — “toward plants as the way to go” — and understanding this is crucial for rheumatologists. “Probably the number one question we get asked is, ‘Doc, what should I eat?’ If we are not well versed to answer that question, it is a huge missed opportunity.”

Here’s a closer look at what we know — and what we don’t know — about diet and RA.

Mediterranean-Style Diet: Big Impact Per Small Studies

Several studies have examined RA and the Mediterranean-style diet, which, according to Carlijn Anne Wagenaar, MD, a researcher at the University of Amsterdam, Amsterdam, Netherlands, emphasizes “vegetables, fruits, whole grains, legumes, nuts, olive oil, and fish, with limited meat and dairy.”

According to her, “it is associated with reduced risks of cardiovascular disease, diabetes, cancer, and overall mortality, largely due to its focus on unprocessed, plant-based foods rich in fiber and polyphenols.”

The RA studies have tended to be small, often with large dropout rates:

• A 2024 randomized controlled trial tested a telehealth-delivered Mediterranean diet intervention vs Irish Healthy Eating Guidelines in 44 adults with RA (87% women). Both groups showed improvements in physical function at 12 weeks, with more improvement in the Mediterranean group. The study authors cautioned that “the changes observed in both diet groups are likely due to the improvement in overall diet quality irrespective of dietary prescription.”
• In a 2003 study, researchers reported improvements in disease activity, vitality, and physical function in 26 patients who followed a Mediterranean diet compared with 25 patients who did not.
• A 2018 study tracked 208 patients with RA and 205 matched control individuals for 3 months and found that those with RA had significantly lower levels of consumption of monounsaturated fatty acids, which are a component of the Mediterranean diet. The study also linked higher intake to less disease activity.
• Researchers taught 75 Scottish women with RA to cook meals based on a Mediterranean-style diet for a study published in 2007. Over 6 months, they had improved global assessment, pain, early morning stiffness, and Health Assessment Questionnaire scores compared with a control group that only got written cooking guidance.
• A study reported at the 2025 European Alliance of Associations for Rheumatology annual meeting tracked 210 patients with RA evenly divided into Mediterranean and regular diet groups. At 3 months, the Mediterranean group had improvements in disease activity and in body weight, BMI, body composition, and muscle mass.

Bose said the Mediterranean diet offers “a pretty good balance and compromise” for patients compared with other diet plans. “Some of them are harder to do than others. It’s easier to maintain a diet that’s not too restrictive.”

However, non-White populations in the US appear to be more resistant to a Mediterranean diet. A 2024 narrative review found that “reported barriers include a lack of familiarity with food components of the diet, food taste, cost of the diet components, culture and eating traditions, food availability, knowledge of the Mediterranean diet, lack of time to prepare and cook foods for the diet, sensory and hedonistic barriers, and the seasonality of food components.”

Anti-Inflammatory Diet: Strict Limits on Foods, Limited Data

At the University of California, San Diego, researchers have developed a strict, modified Mediterranean diet that emphasizes anti-inflammatory properties.

The diet frowns on precooked food, dairy, red meat, and processed meat. It also urges the elimination of tomatoes, potatoes, wheat flour, gluten, salt, and combinations of protein and grains such as pasta and meat.

Instead, the diet supports daily consumption of yogurt, chia seeds, flaxseed oil, leafy vegetables and fruit, enzymatic fruit such as pineapple and mango, green tea, and homemade “green juice.”

A preliminary 2023 analysis of a trial in 44 patients with RA linked the diet to significant improvements in disease activity, pain, and fatigue.

“This was a short trial just to see if people could follow the diet. About 80% of the participants said it was easy to make these dietary changes,” rheumatologist and researcher Monica Guma, MD, told the Arthritis Foundation. “Some are continuing to follow the diet on their own, but there will be times when they don’t. We just tell them to do the best they can.”

A larger trial of two anti-inflammatory diets is ongoing in 124 patients, with results expected later this year.

Vegetarian and Vegan Diets: The Jury Is Still Out

Researchers have also explored vegetarian and vegan diets with mixed results.

The September 2025 systematic review and meta-analysis suggests that they have little impact on RA. But Wagenaar cautioned about the effects of the report’s methodology.

“The significant effects observed in individual studies were not retained,” she said. Still, Wagenaar said the pattern across studies is clear: “Plant-based dietary interventions repeatedly show beneficial effects and may represent an effective adjunct treatment for RA.”

Wagenaar’s own Plants for Joints study was excluded from the meta-analysis because “the intervention was multidisciplinary, combining a whole-food plant-based diet with exercise, stress, and sleep management,” she said.

The initial findings of that parallel-arm, randomized controlled trial involving 77 participants were published in 2023. Wagenaar and colleagues reported that patients with low-to-moderate disease activity who took part in a 16-week lifestyle intervention had better improvements in disease activity, body weight, fat mass, and some other measures.

The effects were sustained: “50% of patients using antirheumatic medication were able to reduce or stop their medication 1 year after the intervention with an average dosage reduction of 62%,” Wagenaar said.

Tough to Study: The Limits of Nutrition Research

Other studies into RA and nutrition are in the works, including a European trial that’s examining the impact of high-fiber diets on RA and expects to be completed by the end of 2026. But only 52 participants are expected to be recruited.

Why aren’t there more large and higher-quality studies about diet and RA?

“Nutrition, in general, is not a particularly easy topic to study, for a variety of reasons,” said Leanna Marderian Wise, MD, assistant professor of clinical medicine in the Division of Rheumatology at the University of Southern California, Keck School of Medicine, Los Angeles. “Often people who eat fairly healthy have other healthy lifestyle habits, such as good exercise patterns, better sleep or work schedules, avoidance of tobacco, or more active social lives. Likely all of these healthy lifestyle patterns are synergistic, and it’s hard to measure just a single one of these items, as well as do a blinded intervention study.”

She noted other methodological challenges: “It’s also hard to measure dietary intake in studies, as people can both overestimate and underestimate. And the quality and/or type of food can also change from one study to another.”

Mechanisms: Theories About Why Diets Matter

Several biological mechanisms may explain diet’s effects on RA, with the gut microbiome emerging as a central focus.

Wise explained how this works: “The type of food we eat, and don’t eat, ultimately affects the bacteria that live in our gut, also known as the gut microbiome. Science shows that the types of bacteria and the way that they live and multiply are very sensitive to food.”

The connection extends to inflammation. “Our systemic immune system also interacts with the gut microbiome, so ‘bad’ bacteria or their by-products can prompt the immune system to start attacking the body,” Wise said. “It’s thought that in a person who might be genetically predisposed to RA…certain eating patterns over time might prompt the development of RA through changing the gut microbiome. They may also either mitigate or worsen the course of RA via the effect of the microbiome on the systemic immune system.”

Wagenaar noted that the high-fiber content in plant-based diets gets “fermented by gut microbiota into short-chain fatty acids, which serve as an energy source for intestinal cells, strengthen gut barrier function, and exert anti-inflammatory effects.”

She also pointed to the “mucosal origins” hypothesis, which suggests “RA may start at mucosal sites in genetically susceptible people before progressing to the joints.”

“In addition, plant-based foods are abundant in unsaturated fats, vitamins, antioxidants, and polyphenols, all of which are linked to anti-inflammatory states,” Wagenaar said. “Processed foods and animal products are associated with higher intake of saturated fats, added salt and sugar, while lacking fiber.”

She highlighted her Plants for Joints study, which “found that the intervention led to reduced inflammatory markers, improved blood glucose, improved LDL [low-density lipoprotein] cholesterol, and thus an overall improved metabolic health state.”

Clinical Impact and Patient Experience

Clinicians report seeing real-world benefits from dietary changes. “Personally, I’ve had patients who have felt effects — both positive and negative — from both good and bad diet choices, respectively,” Wise said. For some individuals with RA, “certain eating patterns may help with symptoms as early as within 2-4 weeks, maybe a little more.”

Some patients have experienced an even quicker impact. “In the Plants for Joints trial, some participants reported that even small amounts of meat seemed to trigger joint pain and swelling the next day,” Wagenaar said. “This is a fascinating observation that deserves further exploration: Is it linked to gut bacteria, and what processes are at play?”

However, Nenad Naumovski, PhD, professor of food science and human nutrition at the Singapore Institute of Technology, cautioned against expecting too much of dietary changes. “Adhering to healthier dietary pattern is not going to cause an immediate impact on day-to-day life,” he said. “These interventions should be implemented as a long-term strategy for improvements in management of RA symptoms.”

How to Educate Patients About the Role of Diet

Specialists agreed that clinicians should actively discuss diet with patients with RA. “It will not replace the need for medication, but following a diet rich in lean protein, vegetables, fruits, spices, and herbs will hopefully serve as an adjunct and maybe help to alleviate some of the patients’ symptoms, both short and long term,” Wise said. “At the very least, maintaining a healthy weight has also been linked to better RA outcomes.”

For patients unwilling to make dramatic changes, Wagenaar recommended starting small: “Aim to eat more fruits and vegetables; swap refined grains for whole grains; cut down or stop eating meat, especially red and processed meat; choose unsweetened and fortified soy or pea milk instead of dairy; add a daily handful of nuts; and eat more legumes.”

Wise added that clinicians should “always recommend starting with the basic dietary guidelines. For many people, that’s already a big step.” She recommended the website Oldways, “which takes the Mediterranean diet and reformats it into culturally adapted eating patterns for different groups.”

As she put it, “Not everyone intuitively understands what the Mediterranean diet is, nor should they. This website lists very healthy eating patterns that are anti-inflammatory yet culturally respectful of the melting pot that the world has become.”

Wagenaar emphasized the importance of not pushing patients to do everything right. “The key message I share with my patients is that it’s not about perfection. Every step toward a more unprocessed, plant-based diet counts. What matters most is making changes you can sustain over time, rather than trying to completely overhaul your diet for a few weeks and then giving up. Small, lasting steps are the real key.”

Wagenaar is director and shareholder of Plants for Health, a company founded to implement the Plants for Joints intervention in healthcare. Katsumoto disclosed an unrestricted grant from Beyond Meat. Other sources reported having no relevant disclosures.

October 13, 2025 — Editor's Note: An earlier version of this article incorrectly described Wagenaar as a rheumatologist and said she had a grant from Beyond Meat. She is a researcher and doesn’t have such a grant.