Inflammation

A vegan diet eased rheumatoid arthritis in a year-long trial

By WhyStopHarmingAnimals.com

Rheumatoid arthritis is an autoimmune disease of the joints, and it responds to what people eat[1]. In a randomized trial published in The Lancet in 1991, patients who moved to a vegan and then lactovegetarian diet had fewer tender and swollen joints, less pain and stiffness, and lower blood markers of inflammation than patients who kept eating ordinary food[1]. The difference was still there a year later[1].

The Lancet trial

Twenty-seven patients began with a fast of 7 to 10 days, then ate a gluten-free vegan diet for three and a half months, then ate a lactovegetarian diet for the rest of the year[1]. Twenty-six controls ate their usual food[1]. In the diet group, tender joints, swollen joints, pain, morning stiffness, grip strength, sedimentation rate and C-reactive protein all improved, and the advantage over the controls held at one year[1].

The trial was small, and its design bundles several changes together: a fast at the start[1], a gluten-free phase[1], and dairy back on the menu for the second part of the year[1]. It can’t say which piece did the most. What it does show is that a diet built around removing animal foods produced improvement that lasted a full year[1].

A shorter, smaller trial

A 2002 study in the Journal of Alternative and Complementary Medicine put 24 people with moderate-to-severe rheumatoid arthritis on a vegan diet with roughly 10% of calories from fat for four weeks[2]. Every measure of symptoms fell significantly except morning stiffness[2]. CRP dropped 16% and rheumatoid factor 10%, but in a group this small neither change reached statistical significance[2].

Why it might work

A 2019 review in Frontiers in Nutrition went through the trials and cohorts and reported symptom improvements on diets that exclude animal products[3]. The authors tie part of the effect to fibre, which shifts gut bacteria toward a profile linked with less inflammation and less joint pain[3].

Beyond the joints

Rheumatoid arthritis isn’t the only autoimmune condition that follows diet[4]. Among 65,981 Adventists, those who ate no animal foods reported about half the prevalence of hyperthyroidism that omnivores did, an odds ratio of 0.49[4]. Lacto-ovo vegetarians (0.65) and pesco-vegetarians (0.74) fell in between, so the less animal food in the diet, the lower the figure[4]. The data were self-reported and collected at a single point in time, so the study can’t say which came first, the diet or the thyroid status[4].