Improvement of Inflammation and Pain after Three Months' Exclusion Diet in Rheumatoid Arthritis Patients.

The short version

This pilot randomised trial with 40 women who have long-standing rheumatoid arthritis (RA) explored whether cutting meat, gluten and lactose from the diet changes pain, quality of life and inflammation. RA is a chronic autoimmune condition in which the immune system attacks the joints, and diet is thought to influence it partly through gut bacteria. Meat, dairy and gluten have been suspected of worsening symptoms, so the researchers compared an exclusion diet, which they call a privative diet, with a balanced diet that kept those foods. At a rheumatology clinic in Chieti, Italy, women aged 31 to 72 on stable RA drugs, all overweight or obese, were randomly assigned to a meat-, gluten- and dairy-free diet with fish as the main animal protein, or to a balanced diet including poultry and dairy. Both diets provided about 1,500 kcal a day to lose weight. After 3 months, 28 completed the study. Pain was rated on a 100 mm visual scale, disease activity with the DAS 28, quality of life with the SF-36 and the Health Assessment Questionnaire, and blood tests tracked inflammation. On the exclusion diet, median pain dropped from 50 to 40 (p = 0.003) and the SF-36 health score rose from 42 to 59 (p < 0.001), whereas the balanced diet showed no significant change. Blood pressure fell (systolic p = 0.003, diastolic p = 0.025), and white cells, neutrophils and the inflammation marker hs-CRP decreased only on this diet. Both diets lowered weight, waist size, fat mass and leptin, but neither changed the DAS 28 joint-activity score or the cytokines measured. Nine people left because the diets were hard to keep and three because of bloating or nausea; none left because of a flare. The authors describe the study as a pilot and caution that the small sample, high dropout, all-female overweight group and lack of a mid-study check limit what can be concluded. They suggest the exclusion diet may carry benefits beyond weight loss alone, and call for larger studies.

Key findings

• In this pilot trial, 40 women with long-standing rheumatoid arthritis (an autoimmune disease of the joints) who were overweight followed either a meat-, gluten- and dairy-free diet or a balanced diet, both about 1,500 kcal a day, for 3 months; 28 finished.
• On the exclusion diet, pain scores fell from a median of 50 to 40 out of 100 (p = 0.003) and overall health on the SF-36 questionnaire rose from 42 to 59 (p < 0.001), while the balanced diet produced no significant change.
• Only the exclusion diet lowered blood pressure and the inflammation marker hs-CRP (a blood test for general inflammation), but the joint disease activity score (DAS 28) did not change with either diet.
• Both diets reduced weight, waist size, fat mass and leptin (a fat-cell hormone linked to inflammation).
• The authors stress this is a small pilot with many dropouts, mainly because strict diets were hard to maintain.

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