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

Kevin D. Cashman, Julie Wallace, Geraldine Horigan, Tom R. Hill, Maria S. Barnes, Alice J. Lucey, Maxine P. Bonham, Nicola Taylor, Emeir M. Duffy, Kelly Seamans, Siobhan Muldowney, Anthony P. FitzGerald, Albert Flynn, JJ Strain, Mairead Kiely

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136 Citations (Scopus)


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 mu g vitamin D3/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 . mu g 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 mu g/d. Intakes were 7.9 and 11.4 mu g/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 mu g/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 mu g vitamin D/d is required, depending on summer sun exposure and the threshold of adequacy of 25(OH)D. This trial was registered at as ISRCTN registration no. ISRCTN20236112. Am J Clin Nutr 2009;89:1366-74.
Original languageEnglish
Pages (from-to)1366-1374
JournalAmerican Journal of Clinical Nutrition
Issue number5
Publication statusPublished (in print/issue) - May 2009


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