[Folic acid in the prevention of neural tube defects]

The term neural tube defects (NTD) stands for anencephaly, iniencephaly, cephalocoele and spina-bifida. The cause of these anomalies is failure of brain spinal cord to properly develop, together with their protective shield of skull and spine, around the 4th gestational week. The prevalence of NTD in continental Europe is 11.2 10,000 live births.

The level of folates in serum can influence the risk of a child affected with NTD. Studies on women with previous pregnancies with NTD showed that supplementary intake of folic acid, with or without other vitamins, preconceptual period throughout the first trimester has a preventive effect on its recurrence. Inadequate intake of folic acid is also connected with preterm delivery, intrauterine growth retardation and placental abruption and infarction.

It is not folic acid, but folates, from the vitamin B group, that can naturally be found in food. There are several groups of folates that differ in the quantity by which they can be absorbed from food. Folates are temperature and storage sensitive and cooking can cause a significant fall of their concentration in food.

The mean daily intake of folates by food is 0.218 mg whereas a reference nutritive intake for a woman of reproductive age is 0.2 mg per day. The currently recommended daily dose for prevention of first NTD occurrence is 0.4 mg, so it is clear that a certain amount of folic acid has to be supplemented preconceptionally and during the first trimester. It can be done in two ways, by telling all women to take it before conceiving, or to fortify food with sufficiently high doses of folic acid in order to achieve adequate serum levels. Neither of the ways is ideal, for not all women would take the supplement, and by aggressively fortifying the food, we create a potential hazard to those that do not need it and may have some problems with the excess of it. The best solution would be a widespread campaign about the need for folic acid and the risks of NTD.

Recommendations of The Expert Advisory Group on Folic Acid in prevention of neural tube defects has several aspects (1) reducing the risk of the first NTD occurrence by preconceptional vitamin supplementation of folic acid in the dose of 0.4 mg day, which would go on until the end of the 12th week (2) reducing the risk of NTD recurrence in offspring of men and women with spina-bifida or with obstetric history affected with NTD by preconceptional vitamin supplementation of folic acid in the dose of 4 mg daily during the first 12 weeks and (3) organizing educational programmes for medical staff as well as the whole population in order to popularize vitamin supplementation.