Optimising Folic Acid Supplementation
Researchers at the UCD Centre for Human Reproduction at the Coombe Women and Infants University Hospital have examined the relationship between timing and duration of folic acid supplementation in achieving red blood cell folate levels in early pregnancy which are optimal for the prevention of neural tube defect.
In a two-year study, over 500 women were opportunistically recruited at their first antenatal visit hospital. Details of folic acid intake were recorded and both red blood cell (RBC) and serum folate levels were determined. A positive correlation was observed between duration of supplementation and both RBC folate and serum folate. The optimal RBC folate level was achieved in 80% of women who started 400ug of folic acid (FA) 4-8 weeks before their last menstrual period (LMP) compared with only 54% in women who started FA intake 4-8 weeks after their LMP.
The study by Cawley et al was published in the Journal of Public Health and featured researchers from Dublin Institute of Technology, Queen’s University Belfast, Dublin City University, Trinity College Dublin, the Health Service Executive and was led by Prof Michael Turner at the UCD Centre for Human Reproduction.
The study provides for the first time information on both the timing and duration of FA that will achieve optimum RBC folate levels associated with the prevention of neural tube defects. The initiation of FA supplementation was clustered around 4-8 weeks after the LMP, when women typically realise that they are pregnant. However just over half of women who commence FA at this time point achieve RBC folate levels necessary to prevent neural tube defects. Less than 10% of women in early pregnancy were meeting the World Health Organisation recommended intake of > 600ug/day dietary folate equivalents. These findings help explain why current supplementation and voluntary food strategies have failed to improve the rates of neural tube defects across Europe over the last 25 years.
The study authors recognise that maternal serum folate levels are possibly more important for the closure of the neural tube than RBC folate levels which reflect storage of folate. The cut-off for optimal serum folate to ensure prevention of neural tube defects has not been established.
The evidence shows that women who are taking 400ug FA need to start before they conceive. The researchers conclude that national and international guidelines need to highlight the importance of women starting FA at least 6 weeks before conception (4 weeks before LMP). Women planning a pregnancy should be advised to start FA at least 6 weeks before trying to conceive if they are to optimize their RBC folate levels. As half of pregnancies are unplanned, the findings confirm that women who could potentially become pregnant should take a daily supplement of FA. Finally, the low total dietary folate intake observed in this study despite voluntary FA food fortification strengthens the need to implement mandatory FA fortification in European countries.
Neural Tube Defects & Folic Acid
Neural tube defects comprise a series of congenital neurodevelopment malformations which carry a heavy burden of illness. Two seminal randomised controlled clinical trials in the early 1990’s demonstrated that neural tube defects could be prevented by having sufficient levels of folic acid in maternal diets prior to conception. As a result, national guidelines were developed across many countries and mandatory food fortification became commonplace. Despite initial Irish recommendations for mandatory fortification of bread with folic acid, this strategy was subsequently deferred in the belief that incidences of neural tube defects were falling due to voluntary diet supplementation. Recent European studies have however found that the levels of neural tube defects are not decreasing and there have been renewed calls for mandatory fortification.
Optimization of folic acid supplementation in the prevention of neural tube defects.
Cawley S, McCartney D, Woodside JV, Sweeney MR, McDonnell R, Molloy AM, Turner MJ.
J Public Health (Oxf). 2017 Oct 20:1-8. doi: 10.1093/pubmed/fdx137. [link to article]
Reproduced with permission