Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa Women's Health Study.

Academic Article

Abstract

  • OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: Greater intake of vitamin D may be associated with a lower risk of RA in older women, although this finding is hypothesis generating.
  • Published In

    Keywords

  • Aged, Arthritis, Rheumatoid, Calcium, Dietary, Female, Follow-Up Studies, Humans, Incidence, Middle Aged, Prospective Studies, Risk Factors, Surveys and Questionnaires, Vitamin D
  • Digital Object Identifier (doi)

    Author List

  • Merlino LA; Curtis J; Mikuls TR; Cerhan JR; Criswell LA; Saag KG; Iowa Women's Health Study
  • Start Page

  • 72
  • End Page

  • 77
  • Volume

  • 50
  • Issue

  • 1