Folic Acid Does Not Show Heart Benefits, Study
Systematic analysis of 8 large trials concluded that the use of folic acid supplements did not appear to be associated with reduced rates of cardiovascular events, although it was shown that low blood levels of homocysteine, an amino acid is considered a risk factor for heart disease and blood vessels.
You can read how Dr. Robert Clark of Oxford University in Britain, and his colleagues in the B-Vitamin Treatment Trialists' Collaboration arrived at this conclusion on the web 11 October 1 issue of the Archives of Internal Medicine, one of the JAMA / Archives journals.
Homocysteine is an amino acid by the body, usually as a byproduct of the digestion of meat they eat.
The researchers wrote in their initial information that the study of cardiovascular disease in children with homocystinuria, a rare genetic disorder that leads to extremely high levels of homocysteine in the blood, leading researchers to assume that high blood levels of amino acids in the general population may have the same result, and suggest it is a risk factor for coronary heart disease, stroke and other vascular diseases of the blood is blocked.
Indeed, trials with B vitamin supplements, as well as folic acid, in particular, led to a decrease in blood homocysteine levels and reduced risk of cardiovascular disease risk among patients with homocystinuria, but several studies involving people with no conditions were unsuccessful.
Thus, the impact on cardiovascular disease in the general population taking folic acid to reduce plasma homocysteine levels somewhat uncertain, said the authors.
That is why in 2004, researchers at the 8 large trials have decided to cooperate in conducting a meta-analysis based on individual data of the participants from all major randomized trials of folic acid-based B-vitamin supplements are designed to lower plasma homocysteine levels for prevention of cardiovascular disease, " they write.
For the study, Clark and his colleagues pooled the results of eight large, randomized, placebo-controlled trials of folic acid involving nearly 37,485 participants with an increased risk of cardiovascular disease. The last trial was completed in 2009.
Total 18 723 participants were randomly assigned to take daily dose of folic acid from 0.8 mg to 40 mg per day, while 18,762 others took placebo or equivalent to a small dose of folic acid.
The tests lasted an average of 5 years.
The results showed that: 9326 Participants major vascular events during the treatment period, 3,010 developed cancer and 5,125 died. In general, those in the active folic acid group experienced an average 25 percent reduction in homocysteine levels. During the median follow-up to 5 years old, was not that big a difference between folic acid and placebo participants bet major vascular events (RR ratio was 1.01, with 95 percent confidence interval, CI of 0.97 to 1.05). In addition, there was little difference between active folic acid and placebo rates of major coronary events and stroke (RR 1.03, CI 0.97-1.10 for coronary; RR 0,96, CI 0.87-1.06 for stroke). There were also no significant differences between active folic acid and placebo for total cardiovascular mortality, total cancer incidence and mortality from cancer, or death from all causes, either during the scheduled treatment period or during the late period of it. Clarke and colleagues concluded that:
"Dietary supplements of folic acid to reduce homocysteine levels had no significant effect for 5 years for cardiovascular events or overall cancer and mortality among the populations studied.
"Doses of folic acid used in all trials included in this meta-analysis exceeded those required for almost minimize homocysteine levels," they wrote.
They also added that the tests they are covered with "found no evidence of treatment benefit lasted for more than five years."
They suggested that, although longer treatment and follow-up may show some benefits, they would be surprised, and their results confirm this, because there is no reason to expect to show the benefits of years later, particularly in the present data with other treatements such as blood pressure-lowering drugs and statins that the benefits tend to appear earlier, during the first few years, rather than later.
One in three adults in the U.S. and one in four in Britain is thought to take folic acid daily, mainly as part of a multivitamin. In addition, in the U.S., fortification of foodstuffs with folic acid to prevent neural tube defects born.
Although this study concludes there are no extra benefits to take folic acid in reducing the cardio-vascular risk, the lack of significant side effects, such as total deaths, cancer deaths, cancer and cardiovascular disease, supports the idea that the population of the entire fortification of foods supply of folic acid is not harmful, the authors suggested.
"The consequences of lowering homocysteine with vitamins on cardiovascular disease, cancer, and cause-specific mortality: a meta-analysis of 8 randomized trials involving 37,485 individuals." Robert Clark, Jim Halsey, Sarah Lewington, Eva Lonn, Jane Armitage, JoAnn E. Manson, Kaare H. Bonaa; J. David Spence, Ottar Nygard, Rex Jamison, J. Michael Gaziano, Peter Guarino, Derrick Bennett; Fraz Mir, Richard Peto, Rory Collins, for the B-Vitamin Treatment Trialists' Collaboration. Arch Intern Med is 170, № 18, p. 1622-1631, published October 11, 2010. DOI: 10.1001/archinternmed.2010.348