The association between vitamin D and incidence of colorectal cancer (CRC) has been thoroughly investigated in both observational and experimental studies, but the results are conflicting. Genetic epidemiology is an advantageous alternative to randomized, clinical trials for ethical and economic reasons.~The aim of this study is to investigate whether polymorphisms in GC and CYP2R1 that predicts 25-hydroxycholecalciferol (25(OH)D) concentrations after both ultraviolet B radiation and consumption of vitamin D3-fortified bread and milk in Danes are associated with risk of CRC; and further, to examine whether intake of vitamin D through diet and supplementation alter the risk of CRC.~Data are retrieved from the Danish prospective Diet, Cancer and Health study encompassing 57,053 persons which were recruited between 1993 to 1997. Between 1994 and 31th December 2009, 1038 CRC cases has been diagnosed. A sub-cohort of 1857 persons has been randomly selected within the full cohort at time of entry into the cohort. The study design is a nested case-cohort study.
The aim of this study is to investigate the interaction between intake of vitamin D and polymorphisms in GC and CYP2R1 in relation to risk of colorectal cancer in a Danish prospective cohort study.