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Drinking four cups of coffee a day may protect against malignant melanoma, a deadly form of skin cancer, a new study has claimed.
Study participants who drank four or more cups of coffee daily were 20 per cent less likely to develop malignant melanoma than non-coffee drinkers, researchers said.
"Our results, and some from other recent studies, should provide reassurance to coffee consumers that drinking coffee is not a risky thing to do," said study researcher Erikka Loftfield, a doctoral student at the Yale School of Public Health and a fellow at the National Cancer Institute.
"However, our results do not indicate that individuals should alter their coffee intake," Loftfield told 'Live Science'.
Loftfield and her team used data from a huge study run jointly by the National Institutes of Health and the American Association of Retired Persons, which tracked 447,357 retirees over 10 years, on average.
Ultimately, in this group, there were 2,904 cases of malignant melanoma (a cancer that has spread beyond the top layer of the skin), and 1,874 cases of early-stage melanoma, which remains only on the top layer of the skin.
The participants reported their coffee consumption as well as other factors that might influence their cancer risk, including exercise, alcohol intake and body-mass index.
To estimate people's UV exposure, the researchers used NASA data on the amount of sunlight in each participant's hometown.
After the researchers controlled for the other factors, coffee drinking turned out to be a boon: There were 55.9 cases of melanoma yearly per 100,000 people among those who drank at least four cups a day, versus 77.64 cases yearly per 100,000 people among the people who didn't drink coffee.
The findings specifically applied to caffeinated coffee, not decaf. It's possible that caffeine itself could be the protective factor, but there could also be some other compound in coffee that protects against malignant melanoma that is more abundant in caffeinated coffee than in the decaffeinated variety, the researchers said.
The study is published in JNCI: Journal of the National Cancer Institute.
