Vitamin D intake is inversely associated with rheumatoid arthritis: Results from the Iowa Women's Health Study
Article first published online: 9 JAN 2004
Copyright © 2004 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 50, Issue 1, pages 72–77, January 2004
How to Cite
Merlino, L. A., Curtis, J., Mikuls, T. R., Cerhan, J. R., Criswell, L. A. and Saag, K. G. (2004), Vitamin D intake is inversely associated with rheumatoid arthritis: Results from the Iowa Women's Health Study. Arthritis & Rheumatism, 50: 72–77. doi: 10.1002/art.11434
- Issue published online: 9 JAN 2004
- Article first published online: 9 JAN 2004
- Manuscript Accepted: 17 SEP 2003
- Manuscript Received: 5 MAR 2003
- Arthritis Foundation
- National Cancer Institute. Grant Number: R01-CA-39741
Vitamin D is a potent regulator of calcium homeostasis and may have immunomodulatory effects. The influence of vitamin D on human autoimmune disease has not been well defined. The purpose of this study was to evaluate the association of dietary and supplemental vitamin D intake with rheumatoid arthritis (RA) incidence.
We analyzed data from a prospective cohort study of 29,368 women of ages 55–69 years without a history of RA at study baseline in 1986. Diet was ascertained using a self-administered, 127-item validated food frequency questionnaire that included supplemental vitamin D use. Risk ratios (RRs) and 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards regression, adjusting for potential confounders.
Through 11 years of followup, 152 cases of RA were validated against medical records. Greater intake (highest versus lowest tertile) of vitamin D was inversely associated with risk of RA (RR 0.67, 95% CI 0.44–1.00, P for trend = 0.05). Inverse associations were apparent for both dietary (RR 0.72, 95% CI 0.46–1.14, P for trend = 0.16) and supplemental (RR 0.66, 95% CI 0.43–1.00, P for trend = 0.03) vitamin D. No individual food item high in vitamin D content and/or calcium was strongly associated with RA risk, but a composite measure of milk products was suggestive of an inverse association with risk of RA (RR 0.66, 95% CI 0.42–1.01, P for trend = 0.06).
Greater intake of vitamin D may be associated with a lower risk of RA in older women, although this finding is hypothesis generating.