Do Vitamin D Levels Affect Colorectal Cancer Risk?
Posted: Tuesday, August 21, 2018
Increased levels of circulating 25-hydroxyvitamin D [25(OH)D] were related to a statistically significant lower colorectal cancer risk in women and a nonsignificant lower colorectal cancer risk in men, according to the findings of an international pooling project of 17 cohorts published in the Journal of the National Cancer Institute. Marjorie L. McCullough, ScD,of the Behavioral and Epidemiology Research Program, American Cancer Society, and colleagues, noted that the optimal concentrations for reducing this risk (75–100 nmol/L) seem to be higher than current recommendations.
Data were collected from 5,706 colorectal cancer case participants and 7,107 control participants with varying circulating 25(OH)D concentrations. The majority of these patients (83.9%) were white, and approximately half were women. These participants were stratified into quintiles based on their sex and circulating 25(OH)D concentrations as well as by the Institute of Medicine (IOM) vitamin D guidance.
Overall, circulating 25(OH)D levels of less than 30 nmol/L (deficiency by IOM) was associated with a 31% increase in colorectal cancer risk, compared with between 50 and 62.5 nmol/L (lower range of sufficiency by IOM). The risk continued to decline at greater levels of sufficiency and beyond sufficiency, 27% lower at between 87.5 and 100 nmol/L. After 100 nmol/L, the risk did not continue to decline. Associations persisted even when adjusting for body mass index, physical activity, nondietary colorectal cancer risk factors, and alcohol consumption. This trend was statistically significant in women but not in men, with Pvalues of less than .001 and equal to .20, respectively.