Background: Vitamin D is a proposed chemopreventive and treatment agent for a variety of cancers. Studies have identified cellular anti-cancer mechanisms as well as associations between low circulating 25(OH)D levels and increased risk of cancer. Recommendations exist for vitamin D supplementation, though published cholecalciferol supplement trials have tested only pharmacological preparations or multivitamins. It is unknown whether intake of over-the-counter (OTC) cholecalciferol supplements, at the estimated average requirement (EAR) recommended by the Institute of Medicine (IOM), changes circulating vitamin D metabolite concentrations and associated biomarkers in healthy adults.

Objective: To determine the effect of 400 IU of OTC cholecalciferol supplements on circulating 25(OH)D concentrations in healthy adults.

Methods: This study was a blinded, randomized, placebo-controlled trial conducted from September 2009 through March 2010 in Tucson, Arizona. A total of 60 healthy male and female residents, aged 35 to 50 years, were recruited. Participants were randomized to receive either 400 IU/d cholecalciferol or a placebo for 30 days. Serum samples were collected every 15 days (± 3 days) and analyzed to determine if the change in circulating 25(OH)D concentration was significantly different between the groups.

Results: After 30 days of supplementation, the net change in circulating concentration of 25(OH)D in the supplement versus placebo group was 2.2 ng/ml (8.5% change, p-value = 0.06). Individuals with low baseline 25(OH)D (<20 ng/ml) had a net change of 4.0 ng/ml (24.4% change, p-value = <0.01), while participants with higher baseline concentration (>30 ng/ml) did not increase significantly (net change 0.3 ng/ml, 0.8%, p-value = 0.84).

Conclusions: Use of OTC cholecalciferol supplements is a common practice, yet there is limited evidence to demonstrate the effectiveness of OTC vitamin D supplements to change circulating 25(OH)D levels. These initial results demonstrate that 400 IU OTC cholecalciferol is sufficient for maintaining the 25(OH)D concentrations of Arizonans throughout the winter, and provide support for the IOM recommended EAR of 400 IU/day in this population. Further research on the optimal dose for chemoprevention is ongoing.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):B103.

Copyright © American Association for Cancer Research
2011