Although the fortification of foods with folic acid has been proven to prevent serious birth defects such as spina bifida, it may also increase the risk of developing cancer, Norwegian researchers report in the November 18, 2009 issue of the Journal of the American Medical Association.
For the study, the research team collected data on 6,837 patients with heart disease from two separate trials. These trials were designed to see if supplemental vitamin Bs could lower homocysteine, a blood protein associated with artery wall damage and an increased risk of heart disease.
People were randomly assigned to receive folic acid (0.8 milligrams) plus vitamins B12 and B6, folic acid plus B12, or B6 alone, or a placebo.
Overall, people who received folic acid had a 21 percent increased risk of developing cancer. In addition, of the 341 patients who received folic acid and developed cancer, 136 died -- a 38 percent increased risk compared with patients who did not take folic acid and developed cancer.
Taking supplemental folic acid was associated with an increased risk of colorectal, lung, prostate and blood cancers.
Since 1998, many countries including Canada have mandated folic acid fortification of white pasta, white flour and enriched cornmeal to decrease the incidence of neural-tube defects in newborns.
While too little folc acid has been linked with an increased risk of some cancers, high doses may pose risk. Previous studies have also hinted that folic acid supplements may boost cancer risk. It's thought that folic acid may accelerate the growth of precancerous or early cancerous growths.
While taking a multivitamin with 0.4 to 1 milligrams of folic acid is recommended for all women of childbearing age to prevent neural tube defects, current evidence suggests that other people should avoid getting more than the daily recommended intake of 0.4 milligrams. Folic acid supplements are not recommended for people with a history of colorectal polyps or colon cancer survivors who are predisposed to develop recurrent precancerous polyps.
LB's note: If you take a multivitamin, ensure it contains no more than 0.4 milligrams of folic acid.
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