The risk of haemorrhagic stroke may be increased by taking vitamin E, scientists have said.
Haemorrhagic stroke is when bleeding occurs in the brain and is one of the least common types of stroke.
It is claimed that taking the vitamin increases the chances of having such a stroke by 22%. Overall, for every 1,250 people taking vitamin E this would account for one extra haemorrhagic stroke.
The strokes can cause brain damage if a weakened blood vessel supplying the brain bursts.
The vitamin could, however, reduce the risk of the most common type of stroke - ischaemic - by 10%, researchers at Harvard Medical School in Boston found.
Ischaemic stroke accounts for 70% of all cases and occurs when a clot prevents blood from reaching the brain. The scientists found that taking vitamin E can cut the risk, equivalent to preventing one ischaemic stroke per 476 people taking the vitamin.
However, they insisted that having a healthy lifestyle and maintaining low blood pressure and cholesterol cut the risk of ischaemic stroke more than taking vitamin E.
Every year, around 111,000 suffer from a stroke - the third biggest cause of death in the UK. Those who survive are frequently left with a disability.
The research, published online in the British Medical Journal, looked at 9 studies involving almost 1.2 million people to investigate the link between vitamin E and stroke.
All participants took a daily dose of at least 50mg of vitamin E.