Antioxidant micronutrients and risk of rheumatoid arthritis in a cohort of older women

The association of antioxidant vitamins and trace elements from foods and supplements with risk of rheumatoid arthritis was evaluated in a prospective cohort study of 29,368 women who were aged 55-69 years at baseline in 1986. Through 1997, 152 cases of rheumatoid arthritis were identified. After controlling for other risk factors, greater intakes (highest tertile vs. lowest) of supplemental vitamin C (relative risk (RR) = 0.70, 95% confidence interval (Cl): 0.48, 1.09; p-trend = 0.08) and supplemental vitamin E (RR = 0.72, 95% Cl: 0.47, 1.12; p-trend = 0.06) were inversely associated with rheumatoid arthritis. There was no association with total carotenoids, α- or β-carotene, lycopene, or lutein/zeaxanthin, while there was an inverse association with β-cryptoxanthin (RR = 0.59, 95% Cl: 0.39, 0.90; p-trend = 0.01). Greater use of supplemental zinc (RR = 0.39, 95% Cl: 0.17, 0.88; p-trend = 0.03) was inversely associated with rheumatoid arthritis, while any use of supplemental copper (RR = 0.54, 95% Cl: 0.28, 1.03) and manganese (RR = 0.50, 95% Cl: 0.23, 1.07) showed suggestive inverse associations with rheumatoid arthritis. Greater intakes of fruit (RR = 0.72, 95% Cl: 0.46, 1.12; p-trend = 0.13) and cruciferous vegetables (RR = 0.65, 95% Cl: 0.42, 1.01; p-trend = 0.07) also exhibited trends toward inverse associations with risk. When the antioxidants were modeled together, only β-cryptoxanthin and supplemental zinc were statistically significant predictors. Intake of certain antioxidant micronutrients, particularly β-cryptoxanthin and supplemental zinc, and possibly diets high in fruits and cruciferous vegetables, may be protective against the development of rheumatoid arthritis.