点击显示 收起
March 2, 2000 (Atlanta) -- Headed for a beach vacation? You might want to pack some vitamin E and beta-carotene supplements, which a new study suggests can help prevent sunburn. But don't pitch the sunscreen just yet. Researchers say more studies are needed to determine how much of the supplements people need to get the protective effects.
Many people already take beta-carotene as a sun protectant, but there has been little research on whether it actually works. So a team of German researchers decided to explore its protective effects, both alone and in combination with vitamin E. Their study is published in the American Journal of Clinical Nutrition.
Before giving them any supplements, the researchers exposed 20 light-skinned men and women to increasing levels of ultraviolet light from a sunlight simulator. Before and after each exposure, their skin color was evaluated with a device called a chromatometer.
The study participants were then randomly assigned to two groups. Group 1 took beta-carotene; group 2 took both beta-carotene and vitamin E. All took the supplements daily for 12 weeks.
Every four weeks during the study period, the levels of beta-carotene in their blood and skin were measured. At these same intervals, they were again exposed to increasing levels of ultraviolet light, and their skin color was evaluated.
Compared with the earlier measurements, skin redness was significantly reduced after eight weeks of the beta-carotene supplements. Redness was further reduced after eight weeks of both supplements, indicating that vitamin E may enhance the protective effect of beta-carotene.
Wilhelm Stahl, PhD, an author of the study and a researcher at Heinrich-Heine-Universitat in Dusseldorf, says the findings are consistent with those of earlier research. "Supplementation results in a sunscreen factor of two or three, meaning that we can withstand two to three times more exposure without a reaction," says Stahl. "But beta-carotene is certainly not a replacement for sunscreen."
Researchers aren't sure whether people can get enough beta-carotene in food to see a sunscreen effect, Stahl tells WebMD. "At present, we don?t know what doses of beta-carotene are optimal for sun protection," he says. "So research is continuing to determine optimal intake from both food sources and nutritional supplements."
In the meantime, dieticians say, the antioxidant effects of beta-carotene and vitamin E help protect against other cancers. "Research has shown that a diet rich in antioxidants helps prevent many cancers and may also inhibit tumor growth," says Wahida Karmally, MS, RD, a spokesperson for the American Dietetic Association and an associate research scientist at Columbia University in New York.
"But very high doses of beta-carotene may have adverse effects, particularly in smokers," Karmally says. "So until more is known about optimal intake, the best approach is to eat a variety of richly colored fruits and vegetables."
Foods high in beta-carotene include carrots, sweet potatoes, apricots, and cantaloupe, Karmally says. Dietary sources of vitamin E include plant oils, green leafy vegetables, and nuts.
The study was supported in part by the Henkel Nutrition and Health Group, a marketer of ingredients used in dietary supplements.