Results of the 10-year study with almost 70,000 people found that intakes of multivitamins and supplements, including selenium and beta-carotene, were not associated with melanoma risk.
Concerns over antioxidants and their potential to increase the risk of skin cancer were recently raised following publication of a randomized, primary prevention trial, called the Supplementation in Vitamins and Mineral Antioxidants (Suvimax) study.
Suvimax found that oral daily supplementation with vitamins C and E, beta-carotene, selenium, and zinc, may increase a woman’s skin cancer risk.
New findings, just published in the August issue of Archives of Dermatology, challenge the Suvimax findings, however.
“These data suggest no association between self-reported multivitamin use and supplemental selenium and beta carotene use similar to doses used in the Suvimax study and melanoma risk,” wrote the researchers, led by Maryam Asgari from Kaiser Permanente Northern California.
“Strengths of this investigation include its prospective design, its large cohort size (about 450 cases), and the availability of baseline information on major potential confounding factors.
“The results of the Suvimax study should be interpreted with caution,” they add.
According to a National Institutes of Health (NIH) State-of-the-Science Panel, half of the American population routinely use dietary supplements, with their annual spend estimated at over $20 billion.
Recent results of the National Health and Nutrition Examination Survey showed that 48 to 55 per cent of the US adult population regularly consumes one or more types of multivitamin product (Am. J. Epidemiol., 2004, Vol. 160, Pages 339-349).
Because so many Americans are consuming supplements regularly, and the concerns raised by Suvimax, “the potential harmful effects of these nutrients is alarming”, said the authors.
Asgari and her co-workers used questionnaires to analyse the diet and supplement use of 69,671 women and men, as well as details about their lifestyle, health history, and other cancer risk factors using a questionnaire.
Intakes of both multivitamins and supplements during the previous 10 years, 451 cases of skin cancer were documented. When the researchers looked at the risk of melanoma associated with long-term supplement, including beta-carotene and selenium at doses comparable to the Suvimax study, no association was found.
"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," wrote the authors. "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."
The study was funded by the National Institute of Arthritis Musculoskeletal and Skin Diseases and the National Cancer Institute.
Source: Archives of Dermatology
2009, Volume 145, Issue 8, Pages 879-882
“Antioxidant Supplementation and Risk of Incident Melanomas: Results of a Large Prospective Cohort Study”
Authors: M.M. Asgari, S.S. Maruti, L.H. Kushi, E. White