Health regulators in the UK and the US are arguing over the levels of folic acid that should be included in food to reduce the risks of spina bifida in newborns. The UK government believes none is needed at all.

The Centers for Disease Control in the US believes that nearly 0.5mg should be added to every 100g of flour, while the Food and Drug Administration says a far lower level is required because many breakfast cereals contain folic acid. They reckon a combination of the two would bring daily intake levels close to 1mg a day, the designated safe upper limit.

The debate is unseemly and unnecessary as it has been proven that even 0.5mg of folic acid a day during pregnancy would halve the 2,500 cases of neural tube defects which include spina bifida and anencephaly which are reported every year in the US.

But even if levels are finally agreed, the regulators will have missed the main issue. Neural tube defects occur as early as 12 days after the first missed period, often before a woman is even sure she is pregnant. It has been reckoned that about a third of women in the UK are increasing their folate intake only after this critical period.

A similar debate is raging in the UK, except it is also still dealing with the more fundamental issue of whether it is necessary at all to put folic acid into bread and flour. The Ministry of Agriculture, Fisheries and Food several years ago concluded that the need for mandatory food fortification was not proven, although nutritional experts resurrected the issue last year and are pressing the government to rethink its policy.

Another vital supplement that women should be taking is iodine either in tablet form or as an oil as it will prevent mental deficiencies in the fetus when they become pregnant.

Although iodine is known to be a preventative if levels are high enough in the woman before she becomes pregnant, Chinese researchers have also discovered it can also help up to the second trimester of pregnancy.

They gave one group of women from the Xinjiang region, an iodine deficient area of China, one 0.1mg tablet of iodine a day during their second trimester. The group gave birth to just 2 per cent of infants with mental deficiencies. However, the figure rose to 9 per cent among those given iodine in the third trimester. (NEJM, December 29, 1994).

Even low levels of lead in the blood can harm the developing nervous system of children, researchers have been discovering over the past 20 years.

Yet despite this, health authorities around the US have been reluctant to introduce screening programmes, even though they have been recommended by health authorities.

Writing in The Lancet (December 10, 1994), Marion Diermayer from the Oregon Health Division said that more than 10 per cent of black and Hispanic children had raised lead levels in their blood, against 3.5 per cent of white children. Lead intoxication among Hispanics has been linked to the use of folk remedies with a high lead content. Also at greater risk are children living in homes built before 1930, presumably because of the types of paint used then.

She urges the introduction of targeted screening among those children at greatest risk.