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Citrus consumption may be linked to increased melanoma risk

Whole grapefruit and orange juice were found to increase skin cancer risk by 36 percent in people who spend a lot of time in the sun or are susceptible to burning.

By Stephen Feller

ALEXANDRIA, Va., July 1 (UPI) -- Frequent consumption of citrus, specifically whole grapefruit and orange juice, has been linked to a 36 percent higher risk of developing melanoma, the deadliest form of skin cancer, according to a large study of American dietary habits.

The study's results were were found to be independent of other factors such as age, physical activity, cigarette smoking, alcohol and coffee intake, and use of vitamin C supplements. Researchers said the association between the fruits and melanoma was stronger for those who were more susceptible to sunburn as a child or spend more time in direct sunlight.

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"While our findings suggest that people who consume large amounts of whole grapefruit or orange juice may be at increased risk for melanoma, we need much more research before any concrete recommendations can be made," said Shaowei Wu, Ph.D., a postdoctoral research fellow in the Department of Dermatology at the Warren Alpert Medical School of Brown University, in a press release. "At this time, we don't advise that people cut back on citrus -- but those who consume a lot of grapefruit and/or orange juice should be particularly careful to avoid prolonged sun exposure."

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Researchers analyzed dietary surveys mailed to 63,810 women and 41,622 men between 1984 and 2010 at various intervals to collect dietary, health and lifestyle information. For the study, researchers excluded people with a history of cancer and defined one serving of citrus fruit as half a grapefruit, one orange or a 6 ounce glass of either fruit's juice.

During the 26-year study, about 1,840 participants, or 1.7 percent, developed melanoma. Data showed that consuming citrus fruit or juice 1.6 times per day increased the risk for melanoma by 36 percent. The association was strongest for whole grapefruits, followed by orange juice, however consumption of whole oranges or grapefruit juice was not linked to melanoma.

The cause of citrus potentially having this effect is caused by furocoumarins, which make the skin more sensitive to sunlight, specifically ultraviolet rays. Furocoumarins are found at higher concentrations in whole fruit, as compared with juices, however the increased effects of orange juice were attributed to its consumption level being many times higher than any other citrus product.

"At this point in time, a public overreaction leading to avoidance of citrus products is to be avoided," said Dr. Marianne Berwick, a professor in the Department of Internal Medicine and Dermatology at the University of New Mexico. "For people who would be considered at high risk, the best course might be to advise individuals to use multiple sources of fruit and juice in the diet and to use sun protection, particularly if one is sun sensitive. There is clearly a need for replication of the study findings in a different population prior to modifying current dietary advice to the public."

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The study is published in the Journal of Clinical Oncology.

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