Folic acid did not prevent heart attacks in heart disease patients receiving supplements of the vitamin over a two-year period, report researchers in the Netherlands.
Folic acid is known to lower plasma homocysteine levels, a marker for heart disease and thought to be a risk factor for atherosclerotic disease, which contributes to heart attacks. However the study, published in the 18 June issue of the Journal of the American College of Cardiology, found that although blood levels of the homocysteine dropped in those receiving the nutrient, they were no less likely to experience heart attack.
The researchers from the University of Amsterdam and Leiden University Medical Center suggest that further trials are needed to assess whether folic acid is merely a marker of the disease, perhaps a symptom, or if it can actually prevent some of the outcomes of heart disease.
In the open-label study, 300 patients with stable coronary artery disease (CAD) were randomised to receive 0.5mg folic acid daily while 293 patients served as controls. All patients had been on statin therapy for an average of 3.2 years.
Two years later, the researchers followed up the treatments. In patients treated with folic acid, plasma homocysteine levels decreased by 18 per cent, whereas these levels remained unaffected in the control group. The primary end point (all-cause mortality and a composite of vascular events) was encountered in 31 (10.3 per cent) patients in the folic acid group and in 28 (9.6 per cent) patients in the control group. The team rated the predictive laboratory parameters for secondary events - homocysteine was less important than levels of creatinine clearance and plasma fibrinogen.
"Homocysteine might therefore merely be a modifiable marker of disease. Thus, low-dose folic acid supplementation should be treated with reservation, until more trial outcomes become available," concluded the researchers.
They added however that the study may not have been long enough to show a significant effect. Other ongoing trials with longer follow-up periods may offer new information.