The evidence points in one specific direction: folic acid reduces the risk of stroke by approximately 16%, but this benefit probably applies only in cases of deficiency. For broader cardiovascular risk and for brain health, the evidence is insufficient. In practical terms, this means that targeted supplementation in the case of a confirmed deficiency can be worthwhile, but taking supplements indiscriminately offers no demonstrated benefit for well-nourished individuals.
Folic acid supplementation reduces the risk of stroke by approximately 16%, according to a large meta-analysis of randomised controlled trials involving nearly 884,000 participants1,2. That is a modest but statistically reliable effect. This applies specifically to stroke, not to cardiovascular disease in general.
For other cardiovascular outcomes, such as heart attack or death from cardiovascular disease, B vitamin supplements show no demonstrable protective effect2. The benefit of folic acid is therefore narrow: there is supporting evidence only for stroke, not for the broader cardiovascular risk.
An important caveat: the benefit of folic acid supplementation appears to be most relevant for people who are deficient. Those who already obtain sufficient folate through their diet are unlikely to gain anything from additional supplements2. This makes indiscriminate supplementation less meaningful for the average well-nourished Western adult.
There is also a safety note. Large amounts of B vitamins, such as those found in certain energy drinks together with caffeine and taurine, have been associated with cardiac arrhythmias, elevated blood pressure, and in rare cases more serious cardiovascular events3. Whether the B vitamins themselves are the culprit, or the combination with other substances, has not been established, but the signals warrant caution with such products.
Regarding brain health specifically, and B vitamins around the time of menopause, these are mentioned in dietary guidelines as protective nutrients, but the evidence base for B vitamins individually is not further substantiated on those points in the available studies4. No quantitative statements about effect size can be made here at this time.
Based on one large meta-analysis of RCTs (nearly 884,000 participants), supplemented by a Cochrane-style systematic review and two smaller observational or guideline studies. The stroke claim has the strongest support; the remaining statements are based on more limited or associative sources.