A new paper analyzes 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:
1. Strength of association
2. Consistency (repeated observation)
3. Specificity (one agent, one result)
4. Temporality (exposure precedes effect)
5. Biological gradient (dose-response relation)
6. Plausibility (e.g., mechanisms)
7. Coherency (no serious conflict with the generally known facts of the natural history and biology of the disease)
8. Experimental verification (randomized, controlled trial)
9. Analogy with other causal relationships
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 in reducing the risk of cancer and many other diseases 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.
Dermato-Endocionology 1:1, 14-21; January 2009 (PDF)
This being said there are other things to consider such as, the right type of oils to be converted to vitamin D in your body.
Cod liver oil, Coconut oil, grass fed butter and dairy carries great oils and fats that will convert easily as well as most fish oils.
Then you have the length of sun exposure for the body type you are. Generally speaking you should still approach over exposure with caution. Taking the sun in 30 minute doses is a great way to use caution no matter the skin type.
Your body uses vitamin D in so many places it would be a shame to have it lacking. Sun is an easy source so go soak it up.