BOSTON—Folic acid fortification may increase the rate at which new cases of colorectal cancer are diagnosed in men and women, according to a hypothesis written by researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University. In the review, published in the July issue of Cancer Epidemiology Biomarkers & Prevention (ePub ahead of print, 2007; July;16(7):1-5), Joel Mason, M.D., director of the USDA HNRCA’s Vitamins And Carcinogenesis Laboratory, and colleagues analyzed data from two national cancer registries— the nationwide Surveillance Epidemiology and End Results (SEER) registry, which publishes cancer occurrence rates and survival data, covering approximately 26 percent of the U.S. population; and Canadian Cancer Statistics, an annual publication by the Canadian Cancer Society and the National Cancer Institute of Canada. “The body's response to folic acid appears to be complex,” said Mason. “While fortification of the food supply is clearly beneficial for women of child-bearing age and their offspring, it is possible that it may, coincidentally, be linked to the increase in colorectal cancer rates. Our report is intended to create a foundation upon which to further explore that possibility.” As Mason and colleagues noted, there is a compelling body of scientific evidence suggesting that high intakes of dietary folate are protective against colorectal cancer. Mason explains, however, that “There are several reasons why we may have inadvertently created the opposite effect with folic acid fortification. First, folate’s pivotal role in DNA synthesis also makes it a potential growth factor for cancerous or pre-cancerous cells, and when administered in large quantities to individuals who unknowingly harbor cancer cells, it could paradoxically enhance cancer development. The addition of substantial quantities of folic acid into the foodstream may have facilitated the transformation of benign growths into cancers, or small cancers into larger ones,” he said. “Second, the fact that a synthetic form of folate is used for fortification may be important,” Mason suggested. “As the total amount of folic acid ingested increases, the mechanism that converts folic acid to methyltetrahydrofolate can become saturated. The left-over folic acid in the circulation might have detrimental effects, as it is not a natural form of the vitamin.”
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