Adherence to Mediterranean diet helps prevent rheumatoid arthritis

Individuals with high adherence to the Mediterranean diet (MD) appear to benefit from a reduced risk of rheumatoid arthritis (RA), suggests a study.

“Our finding provides updated evidence on the importance of diet in RA development and novel directions for the prevention of RA,” the researchers said.

A cohort study and a systematic review with meta-analysis were conducted, involving 117,341 RA-free participants from the UK Biobank in 2006–2010, who were followed for incident RA until 2021.

The researchers calculated the MEDI-LITE score using the consumption of nine food components to estimate adherence to MD and explored the relationship between the MEDI-LITE score and RA risk using a Cox proportional hazard model.

Six databases were searched to identify relevant studies for the systematic review. A meta-analysis was then carried out to pool the effect estimates from the cohort study and identified relevant studies.

A total of 773 participants developed RA during a median follow-up of 9.42 years. The risk of RA was lower in the highest quartile of the MEDI-LITE score (adjusted hazard ratio, 0.713, 95 percent confidence interval [CI], 0.580–0.876) compared with the bottom quartile. [Eur J Clin Nutr 2025;79:888-896]

In the meta-analysis, six studies met the eligibility criteria. Pooled results showed that the highest adherence to MD correlated with a lower risk of RA (odds ratio, 0.838, 95 percent CI, 0.758–0.926) compared with the lowest adherence.

“Although the role of MD in RA pathogenesis is not yet clearly understood, it has been postulated to involve reducing inflammation and promoting weight loss, thereby lowering the risk of developing RA,” the researchers said. [Autoimmun Rev 2018;17:1074-1077] 

Anti-inflammatory

The MD has anti-inflammatory properties that can be attributed to its abundant supply of nutrients, including fibre in vegetables and cereal; carotenoids, flavonoids, and vitamin C in fruits; magnesium in legumes and vegetables; and omega-3 fatty acids in fish and olive oil. [Nutrients 2020;12:1456]

The MD is also low in saturated fatty acids and heme iron in meat, which are considered pro-inflammatory. [Front Cardiovasc Med 2022;9:996467]

There is also evidence supporting the effectiveness of the MD in reducing weight or BMI, both of which are a risk factor in RA development. [Eur J Clin Nutr 2018;72:30-43]

“Obesity can disrupt the immune system, leading to abnormal immune reactions against self-tissues by releasing pro-inflammatory cytokines such as interferon-α and interluekin-6,” the researchers said. [Trends Mol Med 2016;22:88-98; Nat Rev Immunol 2011;11:85-97]

Alcohol consumption

In the cohort study, three components (ie, alcohol, legumes, and olive oil) correlated with the risk of RA, suggesting that the overall effect of the MD could be greater than that of individual foods. 

“The effect of other components might be too small to be detected, and combinations of foods may work synergistically to reduce the risk of RA,” the researchers said. [Br J Nutr 2012;108:577-578]

“Our findings revealed a J-shaped association between alcohol consumption and RA risk, suggesting a protective effect against RA development at moderate levels but heightened susceptibility with excessive intake,” they added. 

This finding is explained by the differential immunomodulatory effects of ethanol concentrations, with moderate alcohol intake inhibiting pro-inflammatory cytokines while heavy drinking disrupts immune homeostasis and a pro-inflammatory state. [Alcohol 2008;42:237-247]