... and destroy natural anticarcinogens.

. . . and destroy natural anticarcinogens

UV-A exposures also reduce the blood levels of carotenoids --plant substances suspected of offering some natural protection against cancer--according to research by Daphne Roe, a Cornell University nutritionist, reported recently in St. Louis at the annual meeting of the Federation of American Societies for Experimental Biology. Carotenoids, of which beta-carotene is the best known example, are the yellow pigments in plants, obtained by eating such foods as squash and tomatoes.

In separate studies, 12 women and 12 men were exposed to 11 UV-A exposures over a two-week period, receiving a skin dose from each less-than-3-minute exposure of on the order of 20 to 25 joules per square centimeter. That's "not a casual exposure,' Roe says, but instead what might be encountered in very intense sunlight. As a result of these exposures, total-carotenoid levels in blood dropped on the order of 30 percent, something Roe terms "very significant indeed.'

She says these data "strongly suggest that sunlight can break down beta-carotene in white and oriental people who are repeatedly exposed to average summer sunshine,' thereby limiting much of the carotenoid's potential "protective benefits against many kinds of cancer.' She hopes to conduct follow-up studies in East Africa to see if intense sun exposures there have similar effects on dark-skinned people.