Antioxidants Pose No Melanoma Threat
Despite earlier study, new report finds no risk from common vitamin and mineral supplements
MONDAY, Aug. 17, 2009 (HealthDay News) -- Vitamins C, E and other antioxidants do not increase the risk for melanoma, the most serious form of skin cancer, a new study found.
A recent study had suggested that the risk for melanoma was increased four-fold among women who took supplemental vitamins C and E, beta carotene, selenium and zinc. Because 48 to 55 percent of U.S. adults take vitamin or mineral supplements, the potentially harmful effects of the supplements was alarming.
"As someone who takes supplements as a preventive measure, I was happy to see that the authors [of the new study] were able to debunk the claims of the prior study," said Dr. Robin Ashinoff, a dermatologist and clinical associate professor of dermatology at New York University Medical Center, who was not involved with the new research.
The new report is published in the August issue of the Archives of Dermatology .
For the study, a team lead by Dr. Maryam M. Asgari, of Kaiser Permanente Northern California in Oakland, collected data on 69,671 women and men who participated in the Vitamins and Lifestyle (VITAL) study. It was designed to look at the use of supplements and the risk for cancer. At the start of the study, between 2000 and 2002, participants completed a questionnaire that included inquiries about lifestyle, medical history, diet, use of supplements and other cancer risk factors.
The researchers found that multivitamins and supplements taken over 10 years, including selenium and beta carotene, were not associated with the risk for melanoma among both women and men.
"Consistent with the present results, case-control studies examining serologic [blood] levels of beta carotene, vitamin E and selenium did not find any association with subsequent risk of melanoma," the authors wrote. "Moreover, the Nurses' Health Study reported no association between intake of vitamins A, C and E and melanoma risk in 162,000 women during more than 1.6 million person-years of follow-up," they added.
The causes of melanoma have to do with genetic predisposition; sun exposure, especially in early life; and other yet-to-be determined factors, Ashinoff said. "Melanoma can occur internally, as in the vagina and GI [gastrointestinal] tract, as well as in the eye, so sun exposure is certainly not the entire story," she said.
Earlier experiments had found that topical antioxidants such as green tea extracts, vitamin C and E and soy can prevent and reverse some of the sun's damage to the DNA and immune systems in the skin, if applied before sun exposure, Ashinoff said.
"It shows how difficult these studies are to interpret," she said. "I am happy to see that these antioxidants have not been shown in a similar group of people to increase the risk of melanoma."
Another study in the same issue of the journal found that most melanomas found by dermatologists are discovered during a full-body examination of the skin. And these melanomas tend to be thinner and more likely to affect only the top layer of skin, making a cure more likely. Melanomas reported by patients tended to be more advanced, the researchers noted.
"It should come as no surprise to anyone that the keen eye of a trained dermatologist is superior to that of laypeople in identifying suspicious lesions and early melanomas," said Dr. Jeffrey Salomon, an assistant clinical professor of plastic surgery at Yale University School of Medicine.
The U.S. National Cancer Institute has more on melanoma.