medwireNews: Vitamin E supplementation may reduce the risk for cancer but only in individuals harboring a particular allele of the catechol-O-methyltransferase (COMT) gene, suggests an analysis of two randomized trials.
Both the Women’s Genome Health Study and Alpha-Tocopherol Beta-Carotene Cancer Prevention Study compared alpha-tocopherol, a form of vitamin E, with placebo, and neither previously demonstrated a chemopreventive benefit of vitamin E supplementation, say Kathryn Hall (Brigham and Women’s Hospital, Boston, Massachusetts, USA) and team.
But when they took the COMT rs4680 genotype into consideration, a random-effects meta-analysis of data from a respective 23,294 and 4631 participants showed that the cancer risk was a significant 12% lower with vitamin E versus placebo among those who were homozygous for the met allele.
By contrast, homozygous carriers of the val allele had a significant 18% higher risk if they took vitamin E, while there was no effect of vitamin E on individuals who were heterozygous.
“These effects indicate the need for additional studies of genetic variation as a determinant of the benefits and possible harms of over-the-counter supplements, like alpha-tocopherol, used for health promotion,” the researchers conclude in the Journal of the National Cancer Institute.
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