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1: Am J Clin Nutr. 2003 Jan;77(1):204-10.Click here to read Links
Erratum in:
Am J Clin Nutr. 2003 Nov;78(5):1047.
Comment in:
Am J Clin Nutr. 2003 Sep;78(3):496-7.

Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol.

Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ.

Creighton University, Omaha, NE 68131, USA. rheaney@creighton.edu

BACKGROUND: The cholecalciferol inputs required to achieve or maintain any given serum 25-hydroxycholecalciferol concentration are not known, particularly within ranges comparable to the probable physiologic supply of the vitamin. OBJECTIVES: The objectives were to establish the quantitative relation between steady state cholecalciferol input and the resulting serum 25-hydroxycholecalciferol concentration and to estimate the proportion of the daily requirement during winter that is met by cholecalciferol reserves in body tissue stores. DESIGN: Cholecalciferol was administered daily in controlled oral doses labeled at 0, 25, 125, and 250 micro g cholecalciferol for approximately 20 wk during the winter to 67 men living in Omaha (41.2 degrees N latitude). The time course of serum 25-hydroxycholecalciferol concentration was measured at intervals over the course of treatment. RESULTS: From a mean baseline value of 70.3 nmol/L, equilibrium concentrations of serum 25-hydroxycholecalciferol changed during the winter months in direct proportion to the dose, with a slope of approximately 0.70 nmol/L for each additional 1 micro g cholecalciferol input. The calculated oral input required to sustain the serum 25-hydroxycholecalciferol concentration present before the study (ie, in the autumn) was 12.5 micro g (500 IU)/d, whereas the total amount from all sources (supplement, food, tissue stores) needed to sustain the starting 25-hydroxycholecalciferol concentration was estimated at approximately 96 micro g (approximately 3800 IU)/d. By difference, the tissue stores provided approximately 78-82 micro g/d. CONCLUSIONS: Healthy men seem to use 3000-5000 IU cholecalciferol/d, apparently meeting > 80% of their winter cholecalciferol need with cutaneously synthesized accumulations from solar sources during the preceding summer months. Current recommended vitamin D inputs are inadequate to maintain serum 25-hydroxycholecalciferol concentration in the absence of substantial cutaneous production of vitamin D.

PMID: 12499343 [PubMed - indexed for MEDLINE]