Study
Comparison of mediterranean and healthy eating guideline interventions on the dietary inflammatory index in rheumatoid arthritis: results from a dietary randomised controlled intervention trial.
In 40 people with rheumatoid arthritis, two diets improved dietary inflammation scores but not patient-reported outcomes.
Summary Do Mediterranean or healthy eating guidelines reduce inflammation in rheumatoid arthritis? Show / hide ↓
Researchers randomly assigned 40 adults with rheumatoid arthritis in Ireland to follow either a Mediterranean diet or Ireland’s healthy eating guidelines for 12 weeks. They used food diaries to calculate a dietary inflammatory index, a score estimating whether someone’s overall diet may promote or reduce inflammation. The score improved in both groups. However, people whose scores improved the most did not report better symptoms or other health measures. They also ate more omega-3 fats and other nutrients, but this was an association within their diets, not a test of omega-3 supplements.
What this means for you: This small study does not show that either diet improved rheumatoid arthritis symptoms, or that omega-3 supplements would help. Eating a generally healthy diet may still be sensible, but this study does not justify buying omega-3 products for rheumatoid arthritis.
weak evidenceThis 12-week dietary randomised trial enrolled 40 adults with rheumatoid arthritis in Ireland. Twenty were assigned to a Mediterranean diet and 20 to the Irish Healthy Eating Guidelines. Dietary Inflammatory Index scores were calculated from food diaries, with the energy-adjusted index, e-DII, as the main reported dietary measure. Baseline e-DII was 0.79±2.60 in the Mediterranean group and 1.20±2.16 in the guideline group; the between-group baseline difference was not significant (p=0.588). e-DII improved within both groups, with p=0.022 for the Mediterranean diet and p=0.004 for the healthy-eating-guideline diet. Despite this dietary-score improvement, patient-reported outcome measures did not differ significantly across tertiles of e-DII change, regardless of diet assignment. Participants in the most anti-inflammatory e-DII tertile reported higher intakes of omega-3 fatty acids, fibre, vitamins A and E, folic acid, and beta-carotene than those in the most pro-inflammatory tertile. This is an association within dietary patterns, not a trial of omega-3 supplementation. It offers no evidence that omega-3 alone changed rheumatoid arthritis symptoms, and it reports dietary scores rather than clinical disease activity or hard outcomes.
Both dietary interventions improved e-DII scores, but no statistically significant change in patient-reported outcomes was observed.
N was 40 and the intervention lasted 12 weeks. Omega-3 was one of several nutrients consumed more often in the most anti-inflammatory dietary tertile, so the study cannot attribute results to omega-3.
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