February 27, 2018

A meta-analysis of 11 trials, published in the October 2017 issue of the American Journal of the Medical Sciences, found an association between supplementation with folic acid and a lower risk of stroke. Folic acid is the synthetic form of folate, an essential B vitamin. Both forms of the vitamin, along with vitamins B6 and B12, can help lower homocysteine, a potentially toxic amino acid which, when elevated, is associated with a greater risk of cardiovascular events.

"Folic acid and B vitamins play important roles in regulating homocysteine metabolism, and it is suggested that folic acid and vitamin B6 and B12 supplementation could reduce plasma homocysteine levels," write authors Tao Tian of Peking Union Medical College in Beijing and colleagues.

Dr Tian and associates selected 11 randomized trials involving a total of 65,790 cardiovascular disease patients for their analysis. Participants received folic acid (with or without other B vitamins) and control subjects received a placebo or usual care. Folic acid doses ranged from 0.5 to 5.0 milligrams folic acid per day for follow-up periods of 12 to 87 months, during which 2,826 stroke events occurred.

By pooling data from all participants, the researchers determined that those who received folic acid had a 10% lower risk of stroke compared to the control subjects. Among men and women who had at least a 25% reduction in homocysteine, supplementation with folic acid was associated with a 15% decrease in stroke risk. "Hyperhomocysteinemia has been identified as a modifiable, independent risk factor for cardiovascular disease, and is associated with an increased risk of stroke,” the authors write. “Considerable experimental evidence has been accumulated to support the role of homocysteine in promoting atherosclerosis, including inducing oxidative stress, enhancing inflammatory responses, and facilitating endothelial dysfunction."

They conclude that the meta-analysis showed that folic acid supplementation is effective among individuals with cardiovascular disease for stroke prevention.