CLOSING THE GAP
The neural tube closes very early in pregnancy – it is completely formed by the end of the sixth week after the last menstrual period. If the neural tube does not close, the infant is born with a neural tube defect (NTD). Failure to close at the cranial end of the neural tube results in anencephaly (absence of the cranial vault and poor brain development) or encephalocoele (localised defect of the skull, also often involving the underlying brain). Non-closure anywhere along the spine results in spina bifida, often with damage to the underlying spinal cord. These are severe birth defects – anencephaly is fatal, and lifelong disability is usual with spina bifida and encephalocoele. There is strong evidence that the B-vitamin folate, in adequate amounts around the time of conception, reduces the risk of a NTD by about 70%. Public health policies promoting periconceptional folic acid supplementation, and mandatory fortification of staple foods have resulted in reductions in NTD in many countries.
Closing Another Gap
In Australia, pre-dating these policies, Aboriginal Australian infants were shown to have a 40% higher prevalence of NTD compared with non-Aboriginal infants. Health promotion of folic acid supplementation, whilst associated with a 30% reduction in NTD in the general population, had no effect on the prevalence in Aboriginal infants, leading to a widening of the disparity between Aboriginal and non-Aboriginal NTD rates (twice as high as for non-Aboriginal infants). In fact, this finding was one of the arguments for instituting mandatory fortification of wheat flour for bread-making in Australia in 2009. In a study of metropolitan and regional Aboriginal adult participants in Western Australia, a significant increase in blood red cell folate was found following mandatory fortification compared with before fortification, while there had been no change in consumption of bread or dietary folate intake apart from that obtained from fortification. Post-fortification, NTD prevalence in Aboriginal infants fell by 68%, closing the gap between Aboriginal and non-Aboriginal rates of NTD.
About the Author – Professor Carol Bowers MBBS MSc PhD FAFPHM DLSHTM FPHA
Professor Carol Bowers is a Senior Research Fellow at the Telethon Kids Institute. Here she worked alongside Professor Fiona Stanley and with Kim Robins to prevent neural tube defects through the promotion of taking folic acid supplements during pregnancy. Carol has qualifications in medicine, epidemiology and public health and her research has a strong focus on investigating causes and effects of birth defects.