Estimation of the dietary requirement for vitamin D in free-living adults >=64 y of age

Am J Clin Nutr. 2009 May;89(5):1366-74. doi: 10.3945/ajcn.2008.27334. Epub 2009 Mar 18.

Abstract

Background: Older adults may be more prone to developing vitamin D deficiency than younger adults. Dietary requirements for vitamin D in older adults are based on limited evidence.

Objective: The objective was to establish the dietary intake of vitamin D required to maintain serum 25-hydroxyvitamin D [25(OH)D] concentrations above various cutoffs between 25 and 80 nmol/L during wintertime, which accounted for the effect of summer sunshine exposure and diet.

Design: A randomized, placebo-controlled, double-blind, 22-wk intervention was conducted in men and women aged >/=64 y (n = 225) at supplemental levels of 0, 5, 10, and 15 microg vitamin D(3)/d from October 2007 to March 2008.

Results: Clear dose-related increments (P < 0.0001) in serum 25(OH)D were observed with increasing supplemental vitamin D(3) intakes. The slope of the relation between total vitamin D intake and serum 25(OH)D was 1.97 nmol . L(-1) . microg intake(-1). The vitamin D intake that maintained serum 25(OH)D concentrations >25 nmol/L in 97.5% of the sample was 8.6 microg/d. Intakes were 7.9 and 11.4 microg/d in those who reported a minimum of 15 min daily summer sunshine exposure or less, respectively. The intakes required to maintain serum 25(OH)D concentrations of >37.5, >50, and >80 nmol/L in 97.5% of the sample were 17.2, 24.7, and 38.7 microg/d, respectively.

Conclusion: To ensure that the vitamin D requirement is met by the vast majority (>97.5%) of adults aged >/=64 y during winter, between 7.9 and 42.8 microg vitamin D/d is required, depending on summer sun exposure and the threshold of adequacy of 25(OH)D. This trial was registered at http://www.controlled-trials.com/ISRCTN20236112 as ISRCTN registration no. ISRCTN20236112.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Calcium / blood
  • Cholecalciferol / administration & dosage
  • Cholecalciferol / blood
  • Cholecalciferol / therapeutic use
  • Dietary Supplements
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Nutritional Requirements*
  • Parathyroid Hormone / blood
  • Seasons
  • Sunlight
  • Vitamin D / administration & dosage
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D / therapeutic use
  • Vitamin D Deficiency / epidemiology

Substances

  • Parathyroid Hormone
  • Vitamin D
  • Cholecalciferol
  • 25-hydroxyvitamin D
  • Calcium

Associated data

  • ISRCTN/ISRCTN20236112