Folic acid supplementation with and without vitamin B6 and revascularization risk: a meta-analysis of randomized...

There is a growing amount of data and a continuing controversy over the effect of folic acid supplementation with and without vitamin B6 on revascularization risk.

We conducted a meta-analysis based on up-to-date published relevant randomized trials to further examine this issue. Relative risk (RR) was used to measure the effect of folic acid supplementation on risk of revascularization using a random-effects model. Total revascularization was defined as any arterial revascularization. Restenosis was defined as stenosis of more than 50 percent of the luminal diameter.

Overall, folic acid supplementation had no significant effect on coronary revascularization (9 trials, n = 27,418, RR = 0.99; 95%CI:0.88-1.11, P = 0.88), coronary artery bypass grafting (CABG) (5 trials, n = 10,703, 0.90; 0.79-1.03, P = 0.11), percutaneous coronary intervention (PCI) (5 trials, n = 10,703, 1.05; 0.89-1.23, P = 0.59), coronary restenosis (3 trials, n = 926, 1.05; 0.89-1.23, P = 0.59) or total revascularization (7 trials, n = 29,314, 1.06; 95%CI: 0.99-1.13, P = 0.10). However, a greater beneficial effect was observed for coronary revascularization among those trials with a moderate dose of vitamin B6 (5-10 mg/d; RR: 0.47; 95%CI: 0.28-0.80, P = 0.005), but not in trials without vitamin B6 or with a high dose of vitamin B6. And a non-significant greater total revascularization risk was observed in trials with a higher folic acid dose (>2 mg/d, RR = 1.11; 95%CI: 0.98-1.25, P = 0.09; ≥5 mg/d, RR = 1.98; 95%CI: 0.93-4.20, P = 0.08).

Our analyses indicate that folic acid supplementation has no significant effect on coronary revascularization, CABG, PCI, coronary restenosis or total revascularization. However, a combination of folic acid and moderate vitamin B6 may be beneficial in reducing coronary revascularization risk.