Twenty-four patients (mean age, 56 years) with moderate-to-severe rheumatoid arthritis consumed a very-low-fat (10% of energy) vegan diet for 4 weeks. Compared with baseline, the severity of pain decreased by 30.6% (p < 0.004), the tender-joint score decreased by 29.1% (p < 0.01), the joint-swelling score decreased by 70.3% (p < 0.02), and the severity of morning stiffness improved by 26.5% (p < 0.04).

Comment: These results suggest that consumption of a very-low-fat vegan diet can produce significant symptom relief in patients with moderate-to-severe rheumatoid arthritis. There are several possible explanations for the positive response, other than a placebo effect. First, a vegan diet eliminates common allergens (such as cow’s milk) that might be a triggering factor for joint inflammation. Second, by eliminating meat, a major dietary source of the pro-inflammatory fatty acid arachidonic acid, a vegan diet may reduce the overall degree of inflammation in the body. Third, plant foods contain a wide array of phytochemicals, some of which have anti-inflammatory activity. Vegan diets are deficient in vitamin B12 and also may contain inadequate amounts of zinc, iron, vitamin D, and protein. Individuals consuming a vegan diet should make sure their diet is balanced, and should take appropriate supplements.

McDougall J, et al. Effects of a very low-fat, vegan diet in subjects with rheumatoid arthritis. J Altern Complement Med 2002;8:71-75