Doctors in the UK have found the vitamin supplement can reduce levels of homocysteine in the body.

This is a key chemical, which has been linked to heart disease.

Everyone over 55 years of age, and in particular anyone with diabetes and existing cardiovascular disease should consider this

Dr David Wald

The doctors found that folic acid can reduce the risks of heart disease by 16% and stroke by 24%.

Their study also found that the supplement can cut the risk of deep vein thrombosis (DVT) by 25%.

Strong evidence

They suggested their findings provided further evidence to support fortifying basic foods like flour with folic acid.

The Food Standards Agency recently ruled out such a policy, saying more study is needed to determine the possible side effects of the vitamin.

The agency had examined the issue after other studies had shown that folic acid can protect babies from neural tube defects such as spina bifida if taken during pregnancy.

Dr David Wald and colleagues at Barts and the London School of Medicine reviewed 72 studies looking at the link between homocysteine levels and heart disease.

They found a strong link between high levels of the chemical and an increased risk of heart disease.

Folic acid is known to reduce levels of homocysteine.

The doctors suggested that people at high risk of heart disease or stroke should take folic acid supplements.

These include people with existing heart disease and everyone over the age of 55.

"Our results indicate that an estimated 16% of heart attacks and about 24% of strokes can be prevented just by taking a folic acid supplement everyday," Dr Wald said in a statement.

"Everyone over 55 years of age, and in particular anyone with diabetes and existing cardiovascular disease should consider this. It would be ineffective, inexpensive and safe."

Fortify food

The doctors suggested that the findings provided evidence that folic acid should be included in basic foods.

Writing in the British Medical Journal, the authors said: "Folic acid could be taken as tablets by high risk patients and possibly supplied to the general public through food fortification or a combination of both."

British Heart Foundation nurses already advise patients to ensure their intake of folic acid is adequate.

Folic acid can be found in green leafy vegetables, root vegetables, mushrooms, fruit, nuts and pulses.

A spokesman for the charity Action Research added: "We have known for some time that folic acid is extremely important for mothers and mums-to-be.

"If folic acid has extra health benefits that would impact on a sizeable sector of society. This ought to be a significant boost to the move towards universal fortification of flour."