Institute of Bone and Joint Surgery

A recent prospective study showed that higher consumption of red meat and total protein was associated with an increased risk of inflammatory polyarthritis. We prospectively investigated the association of protein, iron and corresponding food sources with incident rheumatoid arthritis (RA) in the Nurses Health Study cohort.
We prospectively examined the relationship between diet and incident RA among 82,063 women in the Nurses Health Study. From 1980-2002, 546 incident cases of RA were confirmed by a connective tissue disease screening questionnaire and medical record review for American College of Rheumatology criteria for RA. Diet was assessed at baseline in 1980 and five additional times during follow-up. We conducted Cox proportional hazards models to calculate the rate ratio (RR) of RA associated with intakes of protein (total, animal, and vegetable) and iron (total, dietary, from supplements, and heme iron) and their primary food sources, adjusting for age, smoking, body mass index, and reproductive factors.
The multivariate models showed no association between RA and any measure of protein or iron intake. In comparisons of highest to lowest quintile of intakes, RR=1.17 for total protein [95% confidence interval (CI) 0.89-1.54; P for trend=0.11] and RR=1.04 for total iron (95% CI 0.77-1.41, p for trend=0.82). Red meat, poultry and fish were also not associated with RA risk.
We were unable to confirm an association between protein or meat and risk of RA in this large female cohort. Iron was also not associated with RA in this cohort.