Fol?c Ac?d: B Vitamin Baffles Researchers

By Liebman, Bonnie | Nutrition Action Healthletter, January-February 2006 | Go to article overview

Fol?c Ac?d: B Vitamin Baffles Researchers


Liebman, Bonnie, Nutrition Action Healthletter


"Contrary to expectations, B vitamins may do more harm than good," declared the press release from the European Society of Cardiology Congress in Stockholm in early September.

There, professor Kaare Harald Bonaa of the University of Tromsa reported preliminary results from the Norwegian Vitamin Trial (NORVIT).

"Folic acid and vitamin B-6 in combination may increase the risk of cardiovascular disease," he concluded. And, he added, "further studies are needed to find out whether folic acid accelerates the growth of cancer cells."

Should you stop taking multivitamins? Rummage through your pantry to get rid of any cereals or energy bars with extra folic acid and B-6? Avoid the hundreds of foods made with "enriched wheat flour," which contains added folic acid? No.

Here's a clearer picture of what we know--and don't know--about folate (a B vitamin that occurs naturally in food) and folic acid (a well-absorbed form of folate that's added to supplements and many fortified foods).

Birth Defects

It's clear that folic acid can prevent devastating birth defects.

"Nobody now questions folic acid's protective effect against spina bifida and anencephaly," says Godfrey Oakley, former director of the Division of Birth Defects and Developmental Disabilities at the Centers for Disease Control and Prevention in Atlanta.

Within the first few weeks of pregnancy, the neural tube is supposed to encase the spinal cord. If the tube fails to close, the fetus is left without a brain (anencephaly) or with an exposed spinal cord (spina bifida), which can cause paralysis, learning disabilities, and bowel or bladder problems.

The body needs folate to make DNA and RNA, both essential for rapidly dividing cells. "If you don't have the building blocks for DNA, you can't build the neural tube fast enough," explains Oakley, now a visiting professor of epidemiology at the Rollins School of Public Health at Emory University in Atlanta.

In 1992, a clinical trial found that women who were given a multi-vitamin with folic acid were less likely to have children with neural tube defects than women who got a mineral supplement. (1)

By 1998, the Food and Drug Administration required the food industry to add folic acid (along with three other B vitamins and iron) to the "enriched" flour that's used to make most breads, cereals, and pasta, and to rice, grits, and other grain foods.

"Since fortification, neural tube defects have dropped from 4,000 a year to 3,000," says Oakley. (2) And the drop occurred even though the average woman gets only 100 micrograms a day of folic acid from fortification.

"That's far less than the 400 mcg of folate that the Public Health Service recommends for all women of childbearing age," Oakley notes. (Since neural tube defects often occur before a woman knows that she is pregnant, women can't wait until then to start taking it.)

"Putting folic acid into flour has made a remarkable difference," says Oakley. What's more, he adds, by boosting intakes among people who got the least folate from food, "fortification wiped out folate deficiency anemia in the U.S."

Could extra folate also wipe out heart attacks and strokes?

Heart Attacks & Strokes

If folate protects arteries, researchers believe, it's by lowering blood levels of an amino acid called homocysteine.

"We have very strong evidence from prospective studies that homocysteine is a strong, graded, independent risk factor for cardiovascular events," says J. David Spence, director of the Stroke Prevention and Atherosclerosis Research Centre at the Robarts Research Institute in London, Ontario, in Canada.

Study after study has found a higher risk of heart attacks and strokes in people with high homocysteine levels. (3) Yet that evidence isn't enough to prove that it's homocysteine--and not something associated with the amino acid--that causes heart disease. …

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