Moderate sun exposure offers more health benefits than risks, particularly for people who are deficient in vitamin D or who live in colder, northern latitudes, according to U.S. and Norwegian researchers.
The study found that vitamin D levels, which were calculated based on sun exposure, were linked to survival rates for cancer patients. Those who lived in sunnier, southern latitudes, and had higher vitamin D levels, were less likely to die from cancer than people in northern latitudes.
The researchers analyzed the amount of vitamin D generated by sun exposure at different latitudes, and cross-referenced it with data of cancer incidence and survival rates for people living in varying locations.
They found that people in northern latitudes produce significantly less vitamin D than people nearer to the equator. Specifically, they found Australians produce 3.4 times more vitamin D than people in the United States, and almost five times more vitamin D than Scandinavians.
Meanwhile, rates of major cancers such as colon, lung, breast and prostate increased from north to south, while survival rates decreased from north to south.
The researchers said the findings provide further support for sun-induced vitamin D on cancer prognosis.
Previous studies suggest that vitamin D may protect against cancer by discouraging out-of-control cell reproduction and hindering the formation of new blood vessels for tumors.
Yahoo News January 7, 2008
Proceedings of the National Academy of Sciences January 7, 2008