A study highlighting the link between the cause of a birth defect and that of heart disease reinforces the importance of folic acid in the diet.

A team at the University of Glasgow's department of child health says folic acid will counter the effects of the chemical responsible for both neural tube defects in unborn babies and coronary heart disease in adults.

Neural tube defects - the result of the spinal cord failing to close early in the development of an embryo - can cause spina bifida.

Dr David Stone, a consultant in paediatric epidemiology at the university, said increasing the consumption of folic acid, through supplements or by eating more green vegetables, would reduce the numbers of cases of both conditions.

The findings confirm accepted wisdom for pregnant women while linking the cause of neural tube defects to heart disease in adults.

Link found between a birth defect and heart disease

The study, published in the Journal of Epidemiology and Community Health, supports the view that excess homocysteine - essential for the production of new cells and tissue - is the cause of both conditions.

Dr Stone said: "The rates for the north-west of the British Isles, and Wales and Northern Ireland are the highest in the world for both these conditions, for reasons which are not clear.

Call for folic acid in flour

"What we have suggested is that the similarity is not just chance, but is mediated through a common cause - that is folic acid."

He called for the fortification of flour with folic acid, which was compulsorily introduced in the United States by the Food and Drug Administration in 1996, as a way of raising public consumption.

Dr Stone added: "We think that would have the double benefit of reducing neural tube defects and also reducing the risk of coronary heart disease to the general adult population."

A spokesman for the British Heart Foundation said this study and previous investigations "reinforce the need for adequate consumption of fruit and vegetables in the diet to reduce the risk of cardiovascular disease".

The Association for Spina Bifida and Hydrocephalus said there was conclusive proof daily supplements of folic acid prior to and up to the third month of pregnancy prevented neural tube defect births.