There's increasing evidence that caffeine may help prevent skin cancer. Researchers monitored 112,897 people for more than 20 years, during which time nearly a quarter of them developed the disease. Compared with women who didn't drink coffee, those who drank more than three cups of caffeinated coffee daily had a 20 percent reduction in the risk of basal cell carcinoma (the most common form of skin cancer and the most prevalent cancer overall). Decaffeinated-coffee drinkers didn't have decreased risk. Studies in mice have found that both orally ingested and topical caffeine promote the destruction of UV-damaged skin cells and reduce skin-cancer risk, says Fengju Song, an epidemiologist at Harvard School of Public Health. The new study is one of the largest to confirm the link in humans, and it's the first to show that the effect is specific to basal cell carcinoma, which is diagnosed in about 2 million Americans per year, according to the Skin Cancer Foundation.