Most of the trials were conducted in China, the United States, the United Kingdom, Canada, or Australia. The daily dose of folic acid ranged from 0.4 to 40 milligrams. The intervention duration ranged from 1.5 months to 7.5 years.

The observed risk reductions were generally greater in participants with low baseline serum folate levels or elevated homocysteine levels. There was no effect on all-cause mortality, coronary heart disease, peripheral arterial disease, LDL cholesterol, or HDL cholesterol.

Supplementation with folic acid may reduce the risks of stroke and cardiovascular disease Original paper