Overview Vitamin D Dose-Response

Created February 2011

Need 9600 IU Vitamin D to get most people to 40 ng – with graph Feb 2011

Vitamin D Supplement Doses and Serum 25-Hydroxyvitamin D in the Range Associated with Cancer Prevention

CEDRIC F. GARLAND 1, CHRISTINE B. FRENCH 2, LEO L. BAGGERLY 2 and ROBERT P. HEANEY 3

1 University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, U.S.A.;

2 GrassrootsHealth, P.O. Box 234208, Encinitas, CA 92023, U.S.A.;

3 Creighton University, 2500 California Plaza, Omaha, NE 68178, U.S.A.

Background: Studies indicate that intake of vitamin D in the range from 1,100 to 4,000 IU/d and a serum 25- hydroxyvitamin D concentration [25(OH)D] from 60-80 ng/ml may be needed to reduce cancer risk. Few community-based studies allow estimation of the dose-response relationship between oral intake of vitamin D and corresponding serum 25(OH)D in the range above 1,000 IU/d.

Materials and Methods: A descriptive study of serum 25(OH)D concentration and self-reported vitamin D intake in a community-based cohort (n=3,667, mean age 51.3 ±13.4 y).

Results: Serum 25(OH)D rose as a function of self-reported vitamin D supplement ingestion in a curvilinear fashion, with no intakes of 10,000 IU/d or lower producing 25(OH)D values above the lower-bound of the zone of potential toxicity (200 ng/ml). Unsupplemented all-source input was estimated at 3,300 IU/d.

The supplemental dose ensuring that 97.5% of this population achieved a serum 25(OH)D of at least 40 ng/ml was 9,600 IU/d.

Need 14,100 IU/d to get 97.5% of the population above 50 ng/ml

Conclusion: Universal intake of up to 40,000 IU vitamin D per day is unlikely to result in vitamin D toxicity