Vitamin D and Cancer Survival

Q. Before I was diagnosed with prostate cancer, I was exhausted most of the time. My doctor tested the level of vitamin D in my blood after my diagnosis. It was at 12, well below the minimum!
I just read that vitamin D might reduce the risk of developing certain cancers and that people with adequate levels of this vitamin have better survival stats. How much should I be getting? Is it better to get your vitamin D from the sun or from a pill?
A. Evidence is growing that adequate vitamin D levels reduce the risk of developing many types of cancer (Dermato-Endocrinology, Apr/May/June, 2012). Women with higher vitamin D levels had better survival after diagnosis with breast cancer (Carcinogenesis, online May 23, 2012).
A large study showed higher vitamin D levels were associated with a lower likelihood of lethal prostate cancer (Journal of the National Cancer Institute, May 2, 2012). One protocol suggested benefit for men with prostate cancer who took 4000 IU of vitamin D3 daily (Journal of Clinical Endocrinology and Metabolism, online Apr. 16, 2012). This dose is high, so please check with your doctor before embarking on such a regimen.
We are sending you our Guide to Vitamin D Deficiency with details on testing, signs of deficiency and appropriate dosing. Fatigue is a classic sign of vitamin D deficiency, as are muscle pain and weakness. Some experts think that several minutes of sun exposure a few times a week is better than oral supplements, but this is controversial.