Folic Acid Supplements No Benefit for the Heart, Cancer Risk
Keep taking those folic acid supplements to help prevent birth defects, but do not plan on them significantly helping your heart or reducing your risk of cancer. That’s the word from a meta-analysis published in the October 11 issue of Archives of Internal Medicine.
Folic acid reduces homocysteine but not cardiovascular risk
A trio of B vitamins—folic acid and vitamins B6 and B12—is generally viewed as a combination that helps reduce levels of harmful homocysteine, an amino acid that is created by the body and which is suggested as a potentially modifiable risk factor for stroke and other cardiovascular conditions. However, although folic acid supplements reduce homocysteine levels, the decline does not translate into reduced rates of cardiovascular events, cancer, or death over a five-year period.
To arrive at this conclusion, researchers conducted a meta-analysis of eight large randomized trials in which folic acid supplements were given with the goal of lowering plasma homocysteine levels for the purpose of preventing cardiovascular disease.
Analysis of the eight trials was completed at the end of 2009 and included a total of 37,485 participants. Of these, 18,723 had taken folic acid at doses ranging from 0.8 milligrams (mg; equivalent to 800 micrograms) to 40 mg daily. (By way of reference, the suggested dose for prevention of birth defects is only 400 micrograms.) The remaining 18,762 patients took placebo or an equivalently small dose of folic acid. The trials continued for a median of five years, with the shortest lasting two years and the longest, 7.3.
During the five years, 9,326 participants experienced a major vascular event, 3,010 developed cancer, and 5,125 died. The use of folic acid supplementation reduced homocysteine levels by an average of 25 percent, but the participants who took the supplements were no less likely to experience a major heart or blood vessel event than those who had taken placebo.
Folic acid supplementation also did not result in a significant difference in the number of patients who experienced a major coronary event, stroke, new case of cancer, or death. The researchers concluded that “although some benefit might emerge with even longer treatment and follow-up, the trial results give no reason to expect this.”
In another recent study, this one published in Stroke, investigators at the University of California Los Angeles Stroke Center reported that folic acid supplementation did not have any major impact on preventing stroke. They did note, however, potential mild benefits in primary stroke prevention when folate was used along with B vitamins and in male patients.
Even though the results of the new mega-analysis showed that folic acid supplements do not offer any significant benefits when it comes to preventing cardiovascular events, cancer risk, or death, the good news is that folic acid supplementation—which is widespread—appears to be safe, especially given the high doses used in the trials.
Clarke R et al. Archives of Internal Medicine 2010; 170(18): 1622-30
Lee M et al. Stroke 2010 Jun; 41(6): 1205-12