Is Folic Acid All It's Cracked up to 'B'?

New meta analysis suggests the B vitamin does little for cardiovascular event, cancer risks

/ Author:  / Reviewed by: Joseph V. Madia, MD

Next week marks National Folic Acid Awareness Week. A new meta-analysis from the University of Oxford, England, suggests the water-soluble B vitamin may not quite live up to its lauded reputation.

Folic acid has garnered a kind of renown over the past few years -- as a cancer-fighter, birth-defect defender and heart-health promoter. Since 1988, the vitamin has been added to cereals, flour, breads, pasta and baked goods as per federal law.

But a new report from the University of Oxford suggests folic acid doesn't appear to lower risk of cardiovascular incidents, cancer or death over a five-year period. The vitamin, while appearing to lower blood levels of the amino acid homocysteine (thought to contribute to heart- and blood vessel-disease), was not shown to lower any other potentially modifiable risk factor for coronary heart disease, stroke and other occlusive vascular conditions, according to the study.

By lowering blood homocysteine levels, however, the supplemental B vitamin may reduce cardiovascular-disease risk among individuals with homocystinuria, an inherited disorder that affects the metabolism of the amino acid methionine.

Researchers involved in the B-Vitamin Treatment Trialists' Collaboration combined information from eight clinical trials with 37,485 participants. A total of 18,723 were assigned to take folic acid (0.8 milligrams per day to 40 milligrams per day), while the remaining participants took a placebo or an equivalently small dose of folic acid for a median (midpoint) of five years.

Of all participants, 9,326 experienced a major cardiovascular event, 3,010 developed cancer and 5,125 died. Of those groups, 4,670 (24.9 percent) of initial events occurred in those taking folic acid, compared with 4,656 (24.8) percent in the placebo group. Additionally, no significant distinction appeared between the group taking folic acid and the control group in relation to major coronary events (11.4 percent vs. 11.1 percent), stroke (4.2 percent vs. or 4.4 percent), new cases of cancer or death (13.8 percent vs. 13.6 percent).

The outlook isn't entirely grim for folic acid, however. The supplement is still often given to pregnant or about-to-become pregnant women to prevent miscarriage and birth defects such as spina bifida, which occurs when the fetus' spine and back don’t close during development.

The nutrient -- found naturally in green, leafy vegetables like spinach -- is also used as a natural supplemental therapy for a wide-ranging set of diseases and conditions, including Alzheimer's disease, age-related macular degeneration and restless legs syndrome.

Folic acid, while likely safe for most, can cause a number of serious side effects if too much is taken. These include: abdominal cramps, diarrhea, rash, sleep disorders, irritability, confusion, nausea, stomach upset, behavior changes, skin reactions, seizures, gas and excitability, among others. Unless directed to by a medical professional, you should not take more than 400 mcg of folic acid per day.

The vitamin also has proven adverse interactions with certain medications, especially those used to control seizures, including Dilantin, Cerebyx and Mysoline.

Reviewed by: 
Review Date: 
January 3, 2011