A new study confirms the need for women planning a pregnancy to take folic acid supplements, in order to reduce the risk of serious congenital conditions in their babies. A team of Irish and US researchers has found that around half the population inherit a genetic variation linked to an increased risk of spina bifida and other neural tube defects. However, they say that taking 400mg of folic acid a day, for at least a month before becoming pregnant and during early pregnancy, cancels out this genetic risk.
Between the third and fourth weeks of a human embryo's life, a groove running along its length folds up to make a cylinder called the neural tube, which later grows into the brain and spinal cord. Women trying to conceive are advised to take folic acid daily until the 12th week of pregnancy, because folate (the natural form of folic acid) is essential for this process. Taking folic acid reduces the risk of neural tube defects such as spina bifida and anencephaly, conditions in which the neural tube hasn't closed properly. However, many different genetic and non-genetic factors are thought to trigger these conditions.
Previous research showed that babies who inherit two copies of the 'T' version of the MTHFR gene, which is involved in processing folate, have an increased risk of being born with a neural tube defect. The new study, published online in the British Medical Journal, suggests that those who inherit just one T gene, along with a normal 'C' version, are also more likely to be affected. The 'CT' combination of gene variants appears to increase the risk of neural tube defects by about 50 per cent, whereas the risk for 'TT' individuals is more than double the average. The researchers, based in Dublin, studied 395 affected individuals, aged between five months and 52 years, and 848 healthy people.
The scientists estimate that around 38 per cent of the population inherit the CT gene combination, and ten per cent inherit two T versions. Taken together, they say that the T version of the MTHFR gene accounts for around a quarter of all cases of neural tube defects. But taking folic acid before and during pregnancy appears to cancel out the effects of the T gene variant. Lead author Peadar Kirke, of Dublin's Health Research Board, said: 'This is a rare situation where there is a potential problem during pregnancy, but it can easily be corrected'. He called for flour products to be fortified with folic acid, saying that Europe is 'lagging behind in a very serious negative way in not fortifying food'.