Dietary factors in relation to rheumatoid arthritis: a role for olive oil and cooked vegetables

Background: Although several studies showed that risk of rheumatoid arthrit is (RA) is inversely associated with consumption of n-3 fatty acids, the on e study showing that olive oil may have a protective role has not yet been confirmed. Objective: We examined the relation between dietary factors and risk of RA in persons from southern Greece. Design: We studied 145 RA patients and 188 control subjects who provided in formation on demographic and socioeconomic variables, prior medical and fam ily history, and present disease status. Subjects responded to an interview er-administered, validated, food-frequency questionnaire that assessed the consumption of > 100 food items. We calculated chi-square statistics for li near trend and odds ratios (ORs) for the development of RA in relation to t he consumption of olive oil, fish, vegetables, and a series of food groups classified in quartiles. Results: Risk of developing RA was inversely and significantly associated o nly with cooked vegetables (OR: 0.39) and olive oil (OR: 0.39) by univariat e analysis. A significant trend was observed with increasing olive oil (chi -square: 4.28; P = 0.03) and cooked vegetable (chi-square: 10.48; P = 0.001 ) consumption. Multiple logistic regression analysis models confirmed the i ndependent and inverse association between olive oil or cooked vegetable co nsumption and risk of RA (OR: 0.38 and 0.24, respectively). Conclusions: Consumption of both cooked vegetables and olive oil was invers ely and independently associated with risk of RA in this population. Furthe r research is needed to elucidate the underlying mechanisms of this finding , which may include the antioxidant properties or the high n-9 fatty acid c ontent of the olive oil.