Folic acid fails to protect against cardiovascular disease

doi:10.1136/bmj.333.7581.1266-b

BMJ 2006;333:1266 (16 December), doi:10.1136/bmj.333.7581.1266-b

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Folic acid fails to protect against cardiovascular disease

Folic acid supplements may bring down plasmaconcentrations of homocysteine, but they don't necessarily reducethe risk of cardiovascular disease, according to a meta-analysisof randomised trials. In all 12 trials, folic acid supplements(dose range 0.5-15 mg/day) reduced plasma concentrations ofhomocysteine by 1.5-26 µmol/l, but in none of them didthe change affect participants' risk of coronary heart disease,cardiovascular disease, stroke, or death. Overall, the analysisincluded 16 958 men and women with pre-existing vascular orrenal disease, who took supplements, placebo, or nothing forsix months to five years. About one in five had some kind ofcardiovascular event, regardless of their assigned treatment,and around 12% died.

These findings challenge a large body of observationalwork that has been accumulating since 1969, which links lowerconcentrations of homocysteine with better cardiovascular health,say the authors. Bigger trials are on the way that will bringthe number randomised so far to around 52 000—enough powerto find even a modest reduction in outcomes such as heart disease—ifone exists. For the moment, folic acid does not look particularlyuseful in the secondary prevention of cardiovascular disease.