(ScienceDaily) Patients with heart disease in Norway, a country with no fortification of foods with folic acid, had an associated increased risk of cancer and death from any cause if they had received treatment with folic acid and vitamin B12, according to a study in the November 18 issue of JAMA.
Most epidemiological studies have found inverse associations between folate (a B vitamin) intake and risk of colorectal cancer, although such associations have been inconsistent or absent for other cancers, according to background information in the article. “Experimental evidence suggests that folate deficiency may promote initial stages of carcinogenesis, whereas high doses of folic acid may enhance growth of cancer cells. Since 1998, many countries, including the United States, have implemented mandatory folic acid fortification of flour and grain products to reduce the risk of neural-tube birth defects,” the authors write. “Recently, concerns have emerged about the safety of folic acid, in particular with respect to cancer risk.”
Marta Ebbing, M.D., of Haukeland University Hospital, Bergen, Norway, and colleagues analyzed the results of two Norwegian homocysteine-lowering trials among patients with ischemic heart disease, where there was a statistically nonsignificant increase in cancer incidence in the groups assigned to folic acid treatment. The researchers examined whether folic acid treatment was associated with cancer outcomes and all-cause mortality after extended follow-up. “Because there is no folic acid fortification of foods in Norway, this study population was well suited for such an investigation,” they write.
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