Benefits of Sun Exposure

Most people know too much sun can cause skin cancer. However, did you know too little sun may be just as dangerous? A new study shows a lack of ultraviolet B radiation from the sun is a major cause of many types of cancer.

After analyzing cancer deaths in 500 areas in the United States, William Grant, Ph.D., from Newport News, Va., determined how many additional cancer deaths are caused each year by a lack of sun.

Grant found mortality rates in whites from bladder, breast, colon, esophageal, ovarian, rectal and stomach cancer were twice as high in northeastern states as they were in southern states. Similar patterns were also seen in blacks.

After analyzing the data, Grant determined cancer rates were inversely related to the amount of UV-B radiation a population received.

From his research, Grant predicts a lack of sun will lead to 85,000 additional cases of cancer this year compared to what would take place if the whole country was exposed to the same amount of UV-B radiation as found in the southern region. He also estimates more than 17 percent of the breast cancer cases and more than 17 percent of breast cancer deaths in the country are related to a lack of UV-B radiation.

“The ideal case would, therefore, be to find some way of obtaining the beneficial effects of UV-B exposure without suffering the increased incidence of skin cancer,” writes Grant.

Although UV-B radiation protects against cancer because it contains vitamin D, it has not yet been shown whether vitamin D supplements can substitute for sun exposure. Therefore, Grant strongly suggests more research looking at the relationship between vitamins, UV-B radiation, and cancer. He says further studies, “…should be extremely worthwhile, having the potential to prevent many cases of cancer and save many lives now lost to cancer annually in the United States.”

SOURCE: Cancer, 2002;94:1867-1875