Rheumatoid Arthritis

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Reference: Forsyth, C., et al., The effects of the Mediterranean diet on rheumatoid arthritis prevention and treatment: a systematic review of human prospective studies. Rheumatol Int, 2018. 38(5): p. 737-747.

One-sentence summary: There was insufficient evidence to support the use of the Mediterranean Diet for the prevention of rheumatoid arthritis, but it may provide some benefit for the progression of rheumatoid arthritis.

Study type: A systematic review of two clinical trials (1 randomised controlled trial and 1 controlled clinical trial) and two prospective studies (1 cohort and 1 case-control).

Diet: Mediterranean diet.

Outcomes measured: The risk of developing rheumatoid arthritis (prospective studies) or the progression of rheumatoid arthritis (clinical trials).

Population: Two of the studies were in Sweden, one in the United States and one in Scotland.

Key results:

• Risk of developing rheumatoid arthritis: No significant association with the Mediterranean diet (2 of 2 studies found no association).
• Progression of rheumatoid arthritis: Significant improvements in clinical parameters including pain, physical functioning, swelling, inflammatory markers and/or morning stiffness was reported from a Mediterranean diet intervention in 2 of 2 clinical trials over 3 to 6 months.

Quality assessment: Clinical trials were evaluated using the Cochrane Collaboration’s tool and the prospective studies were evaluated using the National Heart, Lung, and Blood Institute’s quality assessment tool. Both the prospective studies were classified as a moderate risk of bias, whilst the controlled clinical trial and the randomised controlled trial were assessed as a high overall risk and a moderate overall risk of bias respectively.

Limitations:

• Only a small number of studies met the inclusion criteria (4 studies out of 12 full-text articles assessed).
• Both the prospective studies were conducted among Americans, whose general dietary habits differ substantially from a traditional Mediterranean diet, and individuals with the highest adherence score may still not resemble the traditional Mediterranean diet.
• All studies had a moderate to high risk of bias.

The bottom line: There is a promise for the Mediterranean diet in reducing the progression of rheumatoid arthritis, but no evidence for a role in reducing its risk. The evidence for both outcomes is limited and more studies are required. Well-designed prospective studies are needed to determine the protective role of a Mediterranean diet in preventing rheumatoid arthritis.

Other reviews:

Smedslund, G., et al., Effectiveness and safety of dietary interventions for rheumatoid arthritis: a systematic review of randomized controlled trials. J Am Diet Assoc, 2010. 110(5): p. 727-35.