New study links higher B vitamin intake to lower stroke risk

A new study suggests that certain B vitamins may be linked to a lower risk of stroke, adding to growing evidence that diet plays an important role in brain and cardiovascular health.

The research, published in the American Journal of Preventive Cardiology, found that higher intake of several B vitamins was associated with reduced stroke risk—but only up to a certain level of consumption.

Stroke remains a major global health concern, occurring roughly every 40 seconds in the United States, and researchers continue to explore how nutrition may help lower that risk.

The study analysed data from two large population groups: the Women’s Health Initiative and the NIH All of Us Research Program, involving more than 220,000 participants combined.

Researchers examined both dietary intake and blood levels of key B vitamins, including thiamin, riboflavin, niacin, pyridoxine (vitamin B6), folate, and cobalamin (vitamin B12).

In the Women’s Health Initiative dataset, higher intake of several B vitamins was associated with a 10% to 20% lower risk of stroke compared with the lowest intake levels. Similar trends were observed in blood-based measurements, particularly for vitamin B6 and folate.

However, the findings also showed a threshold effect: the protective association appeared to plateau after a certain intake level, and in most cases, additional consumption did not provide extra benefit.

Folate was the exception, continuing to show a potential protective association even at higher intake levels.

Experts caution that the results show an association rather than a direct cause-and-effect relationship, meaning it cannot be confirmed that B vitamins alone reduced stroke risk.

“The ideal would be to do a controlled study,” said Elaine Jones, noting that observational data can only suggest possible links.

Still, researchers believe the biological role of B vitamins may help explain the findings. According to Simin Liu, these nutrients are essential for cellular function and support the health of both blood vessels and the brain, which are directly involved in stroke risk.

Despite the promising results, experts warn against over-supplementation.

“More isn’t always better,” said dietitian Matthew Landry, explaining that excessive intake of certain B vitamins may not provide added benefit and could even reverse potential gains.

Instead, researchers recommend focusing on food-based sources such as leafy greens, whole grains, eggs, dairy products, and lean proteins, which naturally contain a range of B vitamins.

They also note that food processing can reduce vitamin content, making whole, minimally processed foods a better option where possible.

Some individuals, particularly those following vegetarian or restricted diets, may require supplementation, but experts advise consulting a healthcare provider before starting any regimen.