April is Cancer Control Month which invites us to inventory our own personal cancer prevention efforts. Along with proven tactics like eating a “daily rainbow,” staying lean and fit, and supplementing antioxidants, here’s one that may surprise you─vitamin D. An impressive body of research indicates that this unique nutrient—ideally supplemented in the form of cholecalciferol (vitamin D3)—may help both in cancer prevention and treatment.

Vitamin D has emerged as an important factor in the incidence and progression of many malignancies, prostate cancer for starters. Apparently, vitamin D discourages the growth of prostate cancer cells, and also slows the rise of prostate-specific antigen (PSA).1,2 Measuring levels of PSA─a protein produced by cells in the prostate gland─is a primary means of detecting prostate cancer. Vitamin D has also been shown to minimize risk of both colorectal and colon cancer, in part by inhibiting tumor growth.3,4 Numerous studies support the role of vitamin D in breast cancer prevention as well.5,6

How much vitamin D do we need daily for optimal protection against cancer? This is where it gets interesting. While most daily multi-vitamin/mineral formulas offer 400 IU, this level may be too low for effective defense. According to the highly respected Journal of Nutrition, U.S. guidelines for vitamin D intake have failed to adapt to new evidence of no adverse effects at higher doses. In fact, “inappropriately low UL values for vitamin D have hindered objective clinical research on vitamin D and its role in disease prevention, and restricted the amount of vitamin D in multivitamins and foods to doses too low to benefit public health.”7

Cedric Garland, DrPH, professor of family and preventive medicine at UC San Diego Moores Cancer Center, stated that “Daily intakes of vitamin D by adults in the range of 4000-8000 IU are needed to reduce by about 50% the risk of breast cancer, colon cancer, multiple sclerosis, and type 1 diabetes.” Garland mentioned being surprised that the intakes required for disease prevention were significantly higher than the minimal intake of 400 IU/day required to defeat rickets in the 20th century.8

While a study in the American Journal of Clinical Nutrition found 4000 IU to be a safe intake for the average adult,9 evidence from many clinical trials shows─with a wide margin of confidence─that a prolonged daily intake of 10,000 IU of vitamin D3 poses “no risk of adverse effects” for adults, even if this is added to a rather high physiologic (sunshine-derived) background level of vitamin D.10

Based on this information, you may consider taking a closer look at your daily vitamin D intake, especially if you’re determined to avoid cancer through any safe, natural means possible. Food for thought, in any case, no?

1 J Nutr. 2003 Jul;133(7 Suppl):2461S-2469S
2 Recent Results Cancer Res. 2003;164:205-21
3 Expert Rev Gastroenterol Hepatol. 2011 Feb;5(1):67-81
4 Cell Cycle. 2010 Jan 1;9(1):32-7. Epub 2010 Jan 5
5 Curr Oncol Rep. 2010 Mar;12(2):136-42
6 Cancer Causes Control. 2007 Sep;18(7):775-82. Epub 2007 Jun 5
7 J Nutr. 2006 Apr;136(4):1117-22
8 http://health.ucsd.edu/news/2011/02-22-vitamin-D-cancer-risk.htm
9 Am J Clin Nutr. 2001 Feb;73(2):288-94
10Ann Epidemiol. 2009 Jul;19(7):441-5. Epub 2009 Apr 11