A review of 63 previous studies by researchers at the University of California at San Diego came to the conclusion that increased vitamin D levels cut the risk of prostate cancer and other cancers like colon, breast and ovarian.

The summary research also concluded that it doesn't seem to matter whether the vitamin D came from food, supplements or sun exposure.

Strong evidence has already shown that vitamin D supplementation can cut colon cancer risk by almost 50 percent.

The study also confirms that there is good evidence that high vitamin D levels increase the positive outcomes for those who develop cancer.

Analysis:
This research pulls together many studies that indicate that Vitamin D is a potent anti-cancer fighter.

Current recommendations about sun exposure and vitamin D intake are probably too restrictive to allow vitamin D to provide any protective effect and need to be adjusted.

Some camps are recommending a regular small amount of unprotected sun exposure to boost vitamin D levels to therapeutic levels, while others worry that recommending time in the sun will make people overdo their exposure. However, it is time that recommendations about sun exposure take into account the anti-cancer and bone strengthening effects of vitamin D.

Adjustments to the recommended daily intake for vitamin D also need to be made. Research seems to indicate that a protective intake be between 1000 and 2000 IU per day.

Sources:
Garland, Garland, Gorman, et. al. The Role of Vitamin D in Cancer Prevention American Journal of Public Health, Feb. 2006.
Dart, H., Shedding Light on Vitamin D and Cancer, Harvard Center for Cancer Prevention.