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Am J Clin Nutr. 2012 Jun;95(6):1350-6. doi: 10.3945/ajcn.111.031427. Epub 2012 May 2.

Relative effectiveness of oral 25-hydroxyvitamin D3 and vitamin D3 in raising wintertime serum 25-hydroxyvitamin D in older adults.

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  • 1School of Food and Nutritional Sciences, Department of Medicine, University College Cork, Cork, Ireland. k.cashman@ucc.ie

Abstract

BACKGROUND:

The relative potency of 25-hydroxyvitamin D3 to vitamin D3 needs to be better defined so that food-composition tables can better reflect the true vitamin D nutritive value of certain foods.

OBJECTIVE:

We performed a randomized, controlled intervention study in apparently healthy, free-living adults to investigate whether the intake of 25-hydroxyvitamin D3 is 5 times more potent in raising serum 25-hydroxyvitamin D [25(OH)D] during winter compared with an equivalent amount of vitamin D3.

DESIGN:

A randomized, placebo-controlled, double-blind intervention study was conducted in adults aged ≥50 y (n = 56) who consumed a placebo, 20 μg vitamin D3, or 7 or 20 μg 25-hydroxyvitamin D3 daily throughout 10 wk of winter. Serum 25(OH)D was measured by using an enzyme-linked immunoassay, and serum albumin-corrected calcium (S-Ca) was assessed colorimetrically at the baseline, midpoint, and endpoint of the study.

RESULTS:

The mean (±SD) increases (per microgram of vitamin D compound) in serum 25(OH)D concentrations over baseline after 10 wk of supplementation were 0.96 ± 0.62, 4.02 ± 1.27, and 4.77 ± 1.04 nmol · L(-1) · μg intake(-1) for the 20-μg vitamin D3/d and 7- and 20-μg 25-hydroxyvitamin D3/d groups, respectively. A comparison of the 7- and 20-μg 25-hydroxyvitamin D3/d groups with the 20-μg vitamin D3/d group yielded conversion factors of 4.2 and 5, respectively. There was no effect of treatment on S-Ca concentrations and no incidence of hypercalcemia (S-Ca >2.6 nmol/L).

CONCLUSIONS:

Each microgram of orally consumed 25-hydroxyvitamin D3 was about 5 times more effective in raising serum 25(OH)D in older adults in winter than an equivalent amount of vitamin D3. This conversion factor could be used in food-compositional tables for relevant foods. This study was registered at clinicaltrials.gov as NCT01398202.

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PMID:
22552038
[PubMed - indexed for MEDLINE]
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