Diet and Risk for Rheumatoid Arthritis

In a new study published in Annals of Rheumatic Disease, Hu and colleagues^[1] used the extensive Nurses' Health Study data set to investigate the role of diet in the risk for rheumatoid arthritis (RA).

Of the over 76,000 women in the prospective study, over 1000 had confirmed RA. Specifically, the authors of the study evaluated the role of "healthy eating patterns" before a diagnosis of RA, where primary dietary intake was initially assessed by a food frequency questionnaire, a multi-item semiquantitative instrument that assesses intake of a variety of items.

As a next step, the data from the food frequency questionnaire were used to calculate the 2010 Alternate Healthy Eating Index, a high score on which has been associated with reduced risk for a variety of chronic diseases. As an example, a high score would include a diet rich in fruits, vegetables, and whole grains; modest alcohol consumption; and low intake of red meat.^[2]

Overall, a healthy eating pattern as characterized by a higher Alternate Healthy Eating Index score was associated with a nonsignificantly decreased risk for RA. However, in analyses that were adjusted for a variety of factors, including body mass index (BMI) and smoking, a healthier diet was associated with significantly reduced risk for RA in women whose disease onset occurred at 55 years of age or younger, and in particular for women in that age group who developed seropositive RA. Furthermore, of all items assessed, moderate alcohol intake and lower intake of red meat were most associated with reduced risk for RA.

What the Findings Mean Clinically

There is growing knowledge that risk factors for RA are probably acting long before the initial onset of the synovitis that is clinically classifiable as RA.^[3,4] Following this, the results of this study suggest that a generally healthier diet before RA develops is associated with reduced risk for seropositive RA, and in particular in women who have onset of disease before 55 years of age.

These findings, along with other studies in which such factors as lower BMI, increased fatty acid intake, and modest alcohol consumption were associated with reduced risk for RA, suggest that there is a pathophysiologic link between dietary/lifestyle factors and RA.^[5] Indeed, in this new study, Hu and colleagues found that moderate alcohol consumption and lower BMI were associated with reduced risk for RA.

However, it remains to be seen exactly what the mechanisms are that make up this link. In particular, given that the most striking relationship between diet and reduced RA risk in Hu and colleagues' study was seen in younger-onset seropositive RA, it is curious how diet may specifically relate to the development of this disease subtype. Furthermore, given the emergence of several clinical trials for RA prevention,^[6] it remains to be seen what specific dietary interventions may alter risk for development of RA. Specifically, could dietary changes alter risk for progression to RA of individuals who are already at high risk for this disease on the basis of elevated circulating RA-related autoantibody titers?

Let us hope that prospective studies can help address these questions, and that soon, along with possible pharmacologic interventions, we will have compelling data to support the use of judicious dietary and lifestyle changes to reduce risk for RA.