ADVISING women to increase their intake of folic acid to reduce the risk of birth defects does not work, an international study has shown.

In nine European countries and Israel, government recommendations to take extra folic acid have not resulted in any reduction in neural tube defects, of which the best known is spina bifida.

By contrast, fortifying food with folic acid — a policy adopted in America and Canada but rejected by the UK — does work. The number of neural tube defects in Canada has fallen by more than three quarters since folic acid fortification began there in 1996.

The new study, published in the British Medical Journal, looked at the incidence of such defects in Norway, Finland, the Netherlands, England and Wales, Ireland, Hungary, three regions of France, two regions of Italy, Portugal and Israel.

Researchers examined the incidence of neural tube defects before and after governments issued recommendations about folic acid. The study covered more than 13 million births. There was no detectable change associated with the recommendation, the team concluded.

As a result of women not heeding the advice, “thousands of pregnancies that would otherwise have been healthy were affected by neural tube defects”, the researchers said.

The team found that the recommendations did not work because women took no notice of them, or did so for only a short time after the campaigns began. To achieve any lasting effect, a major shift was needed in the proportion of women having adequate amounts of folic acid in their diet, the team concluded.

Fortification of flour, which ensures that women get more folic acid without having to think about it, is effective quickly and at low cost, the team said.

In 2000 the Committee on Medical Aspects of Food and Nutrition Policy recommended that fortification of flour should be introduced in Britain. But the Department of Health first asked the Food Standards Agency to consider the issue. In 2002 the agency called for more research, citing potential risks to the elderly.

As a result, said Andrew Russell, executive director of the Association for Spina Bifida and Hydrocephalus, Britain now lagged behind 30 to 40 countries that have added folic acid to food. “About 100 babies are born every year with spina bifida, and many more are terminated early because the condition has been detected. That’s not a good strategy when you can do primary prevention by adding folic acid to food,” Mr Russell said.

In Canadian research published last September, the incidence of birth defects fell from an average of 4.36 per 1,000 births between 1991 and 1997 to 0.96 per 1,000 between 1998 and 2001. The study detected no ill effects of fortification on the elderly, whose vitamin B12 deficiency can be masked by folic acid.

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