Have You Heard the News on Vitamin D and Cancer?
The media is filled with stories linking vitamin D status with survival rates among patients with advanced colorectal cancer. Since I cannot seem to find an interesting nutrition study published in the past 48 hours, let’s discuss the news.
Yesterday, Medscape Medical News’ Roxanne Nelson published a synopsis of a prospective vitamin D study in 1,000 patients. The study hasn’t been published but the results were reported by researchers at the 2015 American Society of Cancer Oncology.
First, let’s set the record straight: Vitamin D is not a drug that prevents or cures cancer. It is a nutrient. After reviewing the literature, the Committee to Review Dietary Reference Intakes for Vitamin D and Calcium wrote in 2011 [pp 4-17], “Taken in aggregate, epidemiological studies examining associations between vitamin D status and colorectal cancer incidence generally support an inverse association.” People are at risk of deficiency when serum 25(OH)D3 concentrations are below 30 nmol/L (12 ng/mL). The risk of vitamin D inadequacy lies between 30-50 nmol/L (12-20 ng/mL).
Dana-Farber scientists reported an average serum 25(OH)D3 concentration of 43 nmol/L (17 ng/mL). Patients in the lowest group were vitamin D deficient with serum 25(OH)D3 concentrations averaging 20 nmol/L (8 ng/mL). Clearly these 1,000 patients were not meeting criterion of adequacy (> 50 nmol/L) recommended by the IOM but I want to see the peer-reviewed manuscript with all the details.
Sensible sunlight exposure can help maintain vitamin D status above 50 nmol/L (20 ng/mL) but not for people living at polar latitudes during winter months. Since the options for foods naturally-rich in vitamin D are limited, buy vitamin D-fortified foods. Even after taking these steps, many people will benefit from using a vitamin D supplement to maintain serum 25(OH)D3 levels between 60-80 nmol/L.
Hewison M. An update on vitamin D and human immunity. 2012 Clin Endocr doi: 10.1111/j.1365-2265.2011.04261.x
Pludowski P, Holick MF, Pilz S, Wagner CL, Hollis BW, Grant WB, Shoenfeld Y, Lerchbaum E, Llewellyn DJ, Kienreich K, Soni M. Vitamin D effects on musculoskeletal health, immunity, autoimmunity, cardiovascular disease, cancer, fertility, pregnancy, dementia and mortality – A review of recent evidence. 2013 Autoimmun Rev doi: 10.1016/j.autrev.2013.02.004