Brain function, memory and the speed with which information is processed decline as people age but researchers in the Netherlands and Switzerland have found that taking folic acid can help.

"We have shown that three-year folic acid supplementation improves performance on tests that measure information processing speed and memory, domains that are known to decline with age," said Dr Jane Durga of the Nestle Research Center in Lausanne.

Folic acid is a synthetic compound of folate, a B vitamin found in green leafy vegetables, yeast, liver, beans and in some fruits. Women are advised to take folic acid before conceiving and during the early months of pregnancy to prevent disorders such as spina bifida.

British researchers have also shown that folic acid supplements decrease the risk of cardiovascular disease by lowering levels of the amino acid homocysteine, which is thought to damage the inner lining of arteries.