Sunlight & Cancer

The Overwhelming Evidence That Sunlight Fights Cancer
A new paper analyses the case for vitamin D’s cancer-fighting power by looking at the well-known Hill criteria for examining causality in a biological system. The Hill criteria look at:
Strength of association
Consistency (repeated observation)
Specificity (one agent, one result)
Temporality (exposure precedes effect)
Biological gradient (dose-response relation)
Plausibility (e.g., mechanisms)
Coherency (no serious conflict with the generally known facts of the natural history and biology of the disease)
The theory that solar ultraviolet radiation -- and by extension, vitamin D, which is produced when such radiation strikes your skin -- is a potent cancer fighter satisfies most, if not all, of the criteria. From a scientific point of view, therefore, vitamin D reduces the risk of many forms of cancer and increases survival rates once cancer reaches a detectable stage.
However, public policy often lags behind scientific research. It is to be hoped that the acceptance of the beneficial nature of vitamin D will not have too much longer to wait. It is encouraging that the National Academy of Sciences’ Institute of Medicine is currently embarking on a two-year study of vitamin D, and is expected to issue a report in 2010.

from http://v.mercola.com/blogs/public_blog/The-Overwhelming-Evidence-That-Sunlight-Fights-Cancer-74475.aspx