MONDAY, Jan. 14 (HealthDay News) -- Moderately increased sun exposure and optimal vitamin D status may help improve cancer prognoses and also may have more favorable than unfavorable effects on other health outcomes, according to a report published in the Jan. 15 issue of the Proceedings of the National Academy of Sciences.
Johan Moan, Ph.D., of the University of Oslo in Norway, and colleagues used a radiative transfer model and cylinder geometry for the human skin surface to calculate the relative yield of vitamin D photosynthesis as a function of latitude.
Below the equator, the researchers found that the annual yield of vitamin D is 3.4 times higher than in the United Kingdom and 4.8 times higher than in Scandinavia. In populations with similar skin types, they found that the incidence of all major forms of skin cancer increases from north to south. In a surprise finding, they observed a similar geographical pattern for the incidence of major internal cancers. But they also found that cancer prognoses improved from north to south, suggesting that increased sun exposure may have a beneficial effect.
"So far, epidemiological data for cancer argue for an overall positive role of sun-induced vitamin D," the authors conclude. "This message should be addressed to populations at risk for vitamin D deficiency. In view of the supposedly long latency times for cancer manifestation, decades are needed for final evaluation of the impacts of the anti-sun campaigns with respect to melanoma incidence, cancer prognosis, and other possible positive or adverse health effects. Authorities should pay attention not only to skin cancer research, but also to research on vitamin D-sun-health relationships occurring worldwide."
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