Neural tube defects remain one of the most common categories of birth defects in the UK and worldwide, affecting an average of one in every 1000 pregnancies. In 1991, a UK Medical Research Council trial showed conclusively that pre-conceptional supplementation significantly reduced NTD-affected pregnancies by about 70%. This trial and subsequent scientific research led to the recommendation that all women planning a pregnancy should consume a 400 microgram (µg) supplement of folic acid per day, and that women at high risk of having a baby with an NTD should receive 4–5 milligrams (mg) per day.
As NTDs occur within the first 28 days of pregnancy, which is often before a woman knows she is pregnant, the timing of folic acid supplementation is crucial. Dietary interventions include educational campaigns to encourage greater consumption of folate-rich foods, the mandatory and voluntary fortification of foods such as bread, flour and breakfast cereals, as well as the targeted use of food supplements for women of childbearing age.
The nutritional requirement of 400 µg folic acid supplementation prior to and for the first 12 weeks of pregnancy is in addition to the 600 µg required for pregnant women, which is based on the European Food Safety Authority (EFSA) dietary reference values for folate (EFSA J 2014; 12(11): 3893). For pregnant women the Adequate Intake (AI) of 600 µg is derived by EFSA on the basis of maintaining adequate serum and red blood cell (RBC) folate levels.
Taking a daily 400 µg folic acid supplement during this vulnerable period has been a long-term recommendation of the UK Department of Health and the World Health Organisation (WHO). However, there is a continuing need to ensure that women of childbearing age are aware of this advice.
Authorised health claim
The European-wide authorised health claim for a daily 400 µg folic acid supplement, for at least one month before and up to three months after conception, and reduced risk of NTDs in the developing foetus could help transform the communication of this vital public health benefit message to women of childbearing age.
Public health strategy
The UK urgently needs a comprehensive public health strategy for NTD reduction. The UK Scientific Advisory Committee on Nutrition (SACN) has recommended mandatory fortification of flour with folic acid, taking into account the current practices of voluntary fortification and the general use of folic acid food supplements. However, concerns have been raised that long-term exposure of the general population, particularly in the elderly suffering from vitamin B12deficiency, may result in changes to the brain and nervous system. Both folates and vitamin B12have fundamental roles in central nervous system functions at all ages and their metabolism is intimately linked. Vitamin B12 deficiency may also be an independent risk factor for NTDs, and hence dietary interventions with folic acid combined with vitamin B12need to be considered.