Vitamin D and Colorectal Cancer Prevention: A Review of Epidemiologic Studies

Vitamin D is hypothesized to prevent cancer development, and its potential anticarcinogenic effect against colorectal cancer has been explored in epidemiologic studies. Epidemiologic studies found that a low circulating level of 25-hydroxyvitamin D was associated with higher risk of colorectal cancer, whereas the association for vitamin D intake has not been as clear as for circulating vitamin D levels. A large intervention study on vitamin D supplementation and colorectal cancer did not show a protective benefit against colorectal cancer development, but several possible explanations remain open. Genetic polymorphisms in the pathway of vitamin D metabolism also have drawn attention, and single polymorphism studies and Genome Wide Association Studies (GWAS) have been conducted. Given a relatively high prevalence of vitamin D insufficiency among industrialized populations, further research on the optimal dose and duration of vitamin D supplementation, interaction with other nutrients or genes, and the appropriate timing of vitamin D interventions is warranted. © 2012 Springer Science+Business Media New York.