Researchers found that across 14 studies taking vitamin B reduced the risk of having a stroke by around seven per cent.

Vitamin B, which actually consists of a group of 8 vitamins, are generally found in fortified cereals along with meat such as tuna, liver and fruit such as bananas.

Processed foods such as bread, however, tend to contain low levels of B vitamins and so many health experts encourage taking supplements.

Previous studies have revealed conflicting findings for whether vitamin B supplements can help guard against stroke or heart attack. Some have even shown it can increase the risk.

However, researchers at Zhengzhou University in China analyzed 14 clinical trials, involving nearly 55,000 participants.

They found there was a seven per cent lower risk of stroke among those taking the supplements.

There were 2,471 patients suffered strokes but the studies also showed vitamin B resulted in lower levels of a molecule involved in blood clotting called homocysteine.

The authors, whose findings are published in the journal Neurology, said: “Our analysis demonstrated that homocysteine lowering therapy with B vitamin supplementation significantly reduced stroke events.”

However, the researchers found vitamin B supplementation did not have a significant impact on reducing the risk of heart attack.

They also found that folic acid, which is also known as Vitamin B9, could reduce the benefits of taking other vitamin B supplements.

However, many health experts have been pushing to have folic acid added to bread to help ensure pregnant women get enough of the nutrient as it can protect against neurological diseases such as spina bifida in their children.

The researchers also found vitamin B12, which is a common supplement, did not appear to have any impact on stroke risk at high doses.

Previous studies have shown that vitamin B3 can help to improve recovery in patients who have suffered a stroke.

Dr Xu Yuming, another of the authors behind the study, said: “Based on our results, the ability of vitamin B to reduce stroke risk may be influenced by a number of other factors such as the body’s absorption rate, the amount of folic acid or vitamin B12 concentration in the blood, and whether a person has kidney disease or high blood pressure.

“Previous studies have conflicting findings regarding the use of vitamin B supplements and stroke or heart attack.

“Some studies have even suggested that the supplements may increase the risk of these events.”

“Before you begin taking any supplements, you should always talk to your doctor.”

Source: telegraph.co.uk