  |
|
|
|
Recommended levels of folic acid can help prevent birth defects, but too much of this B vitamin may increase your risk for some cancers.
Say “folic acid” and many people immediately think of pregnant women and their need to take enough of this vitamin to help prevent birth defects. But what happens if you take more than “enough”? Does folic acid have a downside? Upside of Folic AcidIn the 1990s, researchers realized that folate (the naturally occurring form of folic acid, which is the form used in supplements and as a food additive) could lower the risk of neural tube birth defects and that many pregnant women were not getting enough of this vitamin. The recommended daily allowance of folate for adults is 400 mcg daily and 600 mcg for pregnant women. So the Food and Drug Administration (FDA) initiated a folate food fortification program. Beginning January 1, 1998, manufacturers were required to add folic acid to enriched breads, flours, cereals, and other grain products. Women of childbearing age were advised to eat foods fortified with folic acid or to take a folic acid supplement, as well as eat folate-rich foods. Since the program started, studies show a significant drop in birth defects such as spinal bifida and anencephaly (no brain). Downside of Folic AcidIf you take a 400-mcg folic acid supplement and also eat folate-rich foods and/or folic acid enriched foods, it is easy to double or even triple the recommended intake of this vitamin. The result, say some studies, is an increased risk of colorectal, breast, and pancreatic cancer. A three-year study reported in the Journal of the American Medical Association involved people who had had a precancerous colorectal polyp (adenoma) removed and who were given 1,000 mcg of folic acid or placebo daily. Use of folic acid was associated with a higher risk of having three or more adenomas and of developing noncolorectal cancers. Several other studies indicate that folate intake increases the risk of breast cancer among postmenopausal women and pancreatic cancer among women and men. In the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, for example, researchers found a 19 percent higher risk of breast cancer in postmenopausal women who were taking at least 400 mcg folic acid daily from supplements. How Much Folic Acid is Safe?The word from experts seems to be to stay around the 400 mcg per day recommended intake, including supplements plus food. If, for example, you routinely eat a breakfast cereal that is fortified with 400 mcg of folic acid, you probably do not need a supplement, especially if you also eat other foods with the vitamin. However, if foods containing folate or folic acid (see list) are not a regular part of your diet, then a supplement (100 to 400 mcg) would be helpful. Food Sources of Folate/Folic AcidThese foods are roughly in order from greatest to least amount of the vitamin per serving. Breakfast cereals fortified 100% (400 mcg) Beef liver Beans Brussel sprouts Spinach Strawberries Asparagus Oatmeal Green peas Broccoli Avocado Peanuts Oranges Romaine lettuce Wheat germ Bagel Eggs Cantaloupe ReferencesLarsson SC et al. Folate intake and pancreatic cancer incidence: a prospective study of Swedish women and men. J Natl Cancer Inst 2006 Mar 15; 98(6): 407-13. Stolzenberg-Solomon RZ et al. Folate intake, alcohol use, and postmenopausal breast cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Am J Clin Nutr 2006 Apr; 83(4): 895-904.
The copyright of the article Folic Acid in Nutrition is owned by Deborah Mitchell. Permission to republish Folic Acid in print or online must be granted by the author in writing.
|
|
|
|
