Studies Find Sun Exposure, Vitamin D Protect Against Cancer

The journal Cancer (March 15, 2002;94(6):1-9) published a study analyzing patterns of sun exposure and cancer rates in a large segment of the U.S. population over a 24-year period spanning 1970 to 1994. The study confirmed prior research showing that moderate exposure to the sun protects from several deadly cancers. These include cancer of the breast, colon, ovary, prostate, and non-Hodgkin’s lymphoma. Dietary differences among population subgroups were minimal and could not account for the difference in cancer rates.

It is believed that ultraviolet radiation from the sun – the same type of radiation linked to skin cancer – protects from other cancers by promoting vitamin D synthesis in the body.

Researchers concluded that: “many lives could be extended through careful exposure to solar UV-B radiation, and vitamin D3 supplementation, especially in the non-summer months.”

Another study also confirmed that vitamin D protects against cancer. Looking at individuals with a prior diagnosis of adenomas who were consequently at increased risk for colorectal cancer, it concluded that vitamin D supplementation has a strong protective effect. In fact, for every 10 ng/ml increase in blood levels of vitamin D within the normal range, the risk of contracting cancer was reduced by 26% (Cancer Epidemiol Biomarkers Prev, Dec 2001;10:1267-1274). It should be noted that vitamin D from sources other than the sun can be toxic, and supplementation beyond a typical multi-vitamin dosage requires professional supervision.

In addition to its cancer-protecting benefits, vitamin D also plays important roles in preventing osteoporosis and preserving muscle function. A recent study showed that elderly people taking vitamin D supplements have a lower occurrence of falls and hip fractures (Am J Clin Nutr, 2002;75:611-615).

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