medwireNews: Following the Mediterranean diet could help reduce the risk for rheumatoid arthritis (RA) among women who smoke, research findings indicate.
“Although the benefits of the [Mediterranean diet] have been proven to reduce overall mortality, cardiovascular diseases, or cancers, its mechanism is not fully understood and might include decreasing inflammation, or increasing antioxidant levels,” explain Marie-Christine Boutron-Ruault (Institut Gustave Roussy, Villejuif, France) and colleagues.
They analyzed data on 62,629 French women from the E3N-EPIC cohort who were each given a Mediterranean diet score out of 9 points, based on their consumption of higher than median amounts of vegetables, legumes, cereal products, fruits and nuts, fish, olive oil, and alcohol. Points were also awarded to people who consumed less than median amounts of meat and dairy products.
Overall, 25.5% of the study participants had a high adherence to the Mediterranean diet, scoring between 6 and 9 points, 45.2% had a medium adherence (4–5 points), and 29.2% had a low adherence (0–3 points).
Incident cases of RA were diagnosed after a mean of 11.7 years, but Mediterranean diet scores were not significantly associated with the likelihood of developing RA.
Of the 480 individuals who developed RA, 24.4% scored high, 44.0% scored medium, and 31.7% scored low on the Mediterranean diet score, equating to a nonsignificant hazard ratio (HR) of 0.86 for RA risk when comparing high and low diet scores.
However, when the women were stratified by smoking status, there was an inverse relationship between the Mediterranean diet score and risk for RA among those who had ever smoked. Indeed, the absolute risk for RA was 38.3 versus 51.5 per 100,000 person–years, respectively, for women with high and low Mediterranean diet scores, respectively.
The researchers emphasize that the absolute risk for RA among women who had ever smoked and had high adherence to the Mediterranean diet was “close to the risk in never smokers with a similar diet,” who had an absolute risk of 35.8 per 100,000 person–years.
They add that the risk for RA among women who had ever smoked reduced significantly by 8% with every 1-point increase in Mediterranean diet score, whereas there was no such association in women who had never smoked.
The authors postulate in Arthritis & Rheumatology that “[i]ncreased oxidant effect of smoking might be counterbalanced by the antioxidant effect of the [Mediterranean diet]. Thus, a strong adherence to a [Mediterranean diet] could reduce the increased risk for RA associated with smoking.”
They conclude: “[Mediterranean diet] could reduce the excess risk of RA in ever smoker women. Our findings must be confirmed in other prospective cohorts.”
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