The Mediterranean diet (MD)—which is rich in olive oils, cereals, fruits, vegetables, fish, and a moderate amount of dairy, meat, and wine—may help protect against rheumatoid arthritis (RA), according to a new study published in Arthritis & Rheumatology.1

RA is an autoimmune disease with multifactorial etiology and 70% of cases affect women. RA is more common in Northern European countries than in Southern European countries. Environmental and lifestyle factors, such as diet, may help to explain this discrepancy, according to the study. Previous research has shown the MD, which is common in Southern European countries, is associated with a variety of health benefits.1

The current study included 62,629 women from France who took part in a questionnaire-based survey assessing dietary habits since 1990. Of the 62,629 women in the study, 480 developed RA.2

Overall, the MD was not associated with RA risk; however, in women who currently smoke or used to smoke, it was associated with a decreased risk. For former and current smokers who followed the MD, the risk was 383 cases per 1 million people per year. For those with a low adherence to the diet, the risk was 515 cases per 1 million people per year.2

“Although the benefits of the MD have been proven to reduce overall mortality, cardiovascular diseases, or cancers [10,22,30,31], its mechanism is not fully understood, and might include decreasing inflammation, or increasing antioxidant levels [29],” the study authors wrote. “In our study, we found an inverse association between a high adherence to MD and the risk of RA only among ever-smoking women, but not among non-smoking women. These could be explained by the differences between smokers and non-smokers in RA pathophysiological mechanisms [6,32].” 

The study authors added that the increased oxidant effect of smoking may be counterbalanced by the antioxidant effect by adherence to the MD. As a result, the increased risk of RA that is associated with smoking may be reduced by strong adherence to the MD.1

The study had several limitations, such as only including French women. Additionally, dietary habits were only recorded once, according to the study authors.1

Reference:
  1. Nguyen Y, Salliot C, Et al. Mediterranean diet and risk of rheumatoid arthritis: findings from the French E3N: EPIC cohort study. Arthritis& Rheumatology. 2020. doi: 10.1102/ART.41487. 
  2. Does the Mediterranean diet protect against rheumatoid arthritis? [News Release] Hoboken, NJ. September 10, 2020. https://www.eurekalert.org/pub_releases/2020-09/w-dtm090920.php. Accessed September 11, 2020.