Vitamin D Cancer Benefits
The vitamin D cancer prevention literature poses a fascinating counter to the idea that we should all avoid sunlight to reduce cancer and disease risk. While reducing sun exposure can help ward off melanoma, keeping your vitamin D status high is one of the best ways to avoid a variety of cancers. This article will explain what we know about how vitamin D prevents cancer, and describe an excellent controlled clinical trial showing exactly that.
It starts with simple observations
The earliest indication that UVB radiation may have something to do with cancer prevention came from a study in 1980, where colon cancer risk was found to be unusually low in the American southwest (1). Subsequent studies showed that prostate, breast, colorectal cancer risks all have strong inverse correlations with latitude and vitamin D status (2,3).
The most paradoxical of all these studies showed that vitamin D levels are also inversely correlated with malignant melanoma incidence (4). On the surface, this fact may seem surprising. But here is a subtle point: vitamin D production peaks after 30 minutes in the sun (5).
Vitamin D Cancer Prevention: How does it work?
The short answer to how does vitamin D prevent cancer is very simple: the activated form of vitamin D, 1,25 dihydroxy vitamin D3, or calcitriol, is a potent inhibitor of cancer cell growth. Calcitriol also prevents normal cells from differentiating into cancer cells (6,7). The primary way that Vitamin D cancer prevention specifically occurs by inhibiting the cancer cell cycle transition from the G1 state to G0. This inhibition occurs through a variety of molecular mechanisms covered in Dusso's review.
Recent research is showing us a different way that vitamin D cancer prevention works. In fact, it works the same way vitamin D
prevents other diseases
: it helps regulate an over-active immune system. This story gets laid out in detail for prostate cancer in a recent study involving gene chip technology. Stanford researchers found that calcitriol downregulated genes involved in the synthesis of the pain signalling molecules called prostaglandins (8). Because one cause of cancer is constant inflammation and irritation (think smoking for lung cancer), reducing prostaglandin synthesis helps reduce risk.
The vitamin D cancer survival connection: An emerging trend
Some evidence is emerging that cancer survival rates can be increased by improved vitamin D status (2). In a finding that is reminiscent of the
discovery of vitamin D
in the first place, doctors began taking note of a seasonal influence on the postoperative survival of cancer patients. this finding as worked it's way into more rigorous studies showing some significant influence of vitamin D intake and surgery season on remission-free survival rates (9).
The bottom line
The vitamin D cancer connection is quite clear in the scientific literature. A recent 5 year, randomized clinical trial of over 1100 women established that vitamin D supplementation significantly reduced risk of cancer diagnosis (10). The real question now is how much vitamin D do I need? This is not a trivial question. Get some facts here:
How vitamin D cancer prevention can help you
1. Garland, CF, Garland, FC. "Do sunlight and vitamin D reduce the likelihood of colon cancer?" Int J Epidemiol. 9 (1980) 227-231.
2. Grant, , WB. "Epidemiology of disease risks in relation to vitamin D insufficiency." Prog Biophys Mol Biol. 92 (2006) 65-79.
3. Holick, MF. "Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis." Am J Clin Nutr. 79 (2004) 362-71.
4. Millen, AE, Tucker, MA, Hartge, P, et al "Diet and melanoma in a case-control study." Cancer Epidem. Biomarkers Prev. 13 (2004) 1042-51.
5. Zimmerman, A. "Vitamin D in preventative medicine: are we ignoring the evidence?" Br J Nutr. 89 (2003) 552-72.
6. Dusso, AS, Brown, AJ, Slatopolsky, E. "Vitamin D." Am J Physiol Renal Physiol. 289 (2005) F8-F28.
7. Lin, R, White, JH. "The pleiotropic actions of vitamin D." BioEssays 26 (2003) 21-28.
8. Moreno, J, Krishnan, AV, Feldman, D. "Molecular mechanisms mediating the antiproliferative effects of Vitamin D in prostate cancer." J Steroid Biochem Mol Biol. 97 (2005) 31-36.
9. Zhou, W, Suk, R, Liu, G, et al. "Vitamin D is associated with improved survival in early stage non-small cell lung cancer patients." Cancer Epidem. Biomarker Prev. 14 (2005) 2303-9.
10. Lappe, JM, Travers-Gustafson, D, Davies, KM, et al. "Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial." Am J Clin Nutr. 85 (2007) 1586-1591.