Sinéad Howley: We must not become complacent about folic acid supplementation

Folic acid is to be added to UK flour, according to newspaper reports. The Guardian report that ministers have agreed to folic acid fortification in an effort to reduce birth defects—a move that has been praised by medical groups and health charities.

While the news is hugely welcome, it is important to remember that fortification and supplementation are complementary measures to reduce neural tube defects. We need to ensure that we do not become complacent about continuing to educate women of reproductive age to take a daily folic acid supplement. Fortifying flour with folic acid will serve as a safety-net to catch those women who do not take folic acid supplements, but it is by no means an alternative to taking a daily folic acid tablet.

It has been over 25 years since a landmark paper on folic acid by the Medical Research Council showed that folic acid supplementation can help prevent neural tube defects in babies. [1] Yet there is still extremely poor awareness among women regarding when to take folic acid supplements. Recent studies from Spain and the Republic of Ireland reveal that less than 25% of pregnant women take folic acid supplements correctly in the pre-conception period. [3, 4, 5] In the UK, a cross-sectional study of almost half a million women who attended for antenatal screening in London revealed a decline in the proportion of these women taking folic acid supplements pre-conception from 35% in 1999-2001 to 31% in 2011-2012. [6]

In my own work as a GP, I meet on average one woman every week who presents for her first antenatal visit at around five weeks pregnant. When I ask her whether she has started taking folic acid, a frequent reply is “yesterday when the pregnancy test was positive”. This is very frustrating to me as a doctor as she has missed most of the critical period where she needed to be on folic acid to reduce the risk of birth defects. As medical providers we bear some responsibility that we haven’t given her this information in advance of her pregnancy.

As GPs there are plenty of occasions to opportunistically discuss folic acid supplements in consultations with women of reproductive age, in much the same way as we promote regular cervical smears and smoking cessation. We could also be incorporating a reminder to women to take daily folic acid as part of their “pill check” consultation. No form of contraception is 100% effective so all women who are on contraception should also be on daily folic acid.

One of the biggest challenges for doctors in conveying this message is that often the public perception around folic acid is that it is only taken during pregnancy. Around a third of women are still not aware that folic acid supplements are needed before pregnancy, which means that even for women who “plan a pregnancy”, less than two-thirds would be in a position to consider taking folic acid supplements as recommended in the pre-conception period. [4] And for the half of all pregnancies that are unplanned, the proportion of those women who take folic acid supplements pre-conception is presumably negligible, and likely accounts for the overall very low rate of adherence with pre-conception folic acid supplements.

Another challenge we face in both folic acid supplementation and fortification are concerns around what level of folic acid might cause harm. [7] It was previously believed that taking folic acid in the presence of a Vitamin B12 deficiency could exacerbate or precipitate neurological damage. However this concern partly arose from studies conducted in the 1950s when it was not easy to determine the difference between folic acid deficiency and Vitamin B12 deficiency—something that is nowadays routinely performed by doctors. [8] There is still some debate about whether we can say with 100% certainty that folic acid plays no role in exacerbating Vitamin B12 deficiency. [7, 9] To this end, there have been suggestions around also advising for Vitamin B12 fortification if there is to be folic acid fortification of foods. [7, 9] However, in terms of supplementation, there are no guidelines at present advising for women to take routine Vitamin B12 supplementation in addition to folic acid.

Regardless of whether a country has folic acid flour fortification or not, it is imperative that we offer women clear advice to take daily folic acid tablets. In the US, where there has been folic acid fortification since 1998, they advise that all women from ages 15 through 45 take daily folic acid supplementation, which is something that should be considered by European countries. [10]

As doctors, we must make time to encourage women of reproductive age to make folic acid supplements part of their daily routine whether or not they are planning a pregnancy, and whether or not they live in a country with fortified flour.

Sinéad Howley is a GP based in Dublin.

Competing interests: SH is running a Folic Acid Awareness Campaign. In support of this, she has received non-financial support from Clonmel Healthcare.

Provenance: peer reviewed, not commissioned


  1. Prevention of neural tube defects: Results of the Medical Research Council Vitamin Study. Wald et al, 1991 The Lancet (1991) Vol 338 (8760): 131-137
  2. “Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation” Andrew E. Czeizel et al, 1992. The New England Journal of Medicine (1992) 327(26): 1832-5
  3. Safefood website– accessed online October 2018
  4. The folate status of pregnant women in the Republic of Ireland; the current position. Safefood, 2017 – accessed online October 2018
  5. Use of high doses of folic acid supplements in pregnant women in Spain: an INMA cohort study. Eva María Navarrete-Muñoz et al, 2015 BMJ Open (2015) Nov 24;5 (11)
  6. Prevention of Neural Tube Defects: A Cross-Sectional Study of the Uptake of Folic Acid Supplementation in Nearly Half a Million Women. Jonathan P. Bestwick et al, 2014 PLoS ONE 9(2)
  7. Do the benefits of folic acid fortification outweigh the risk of masking vitamin B12 deficiency?  BMJ Head to Head 2018, 360, k724
  8. Public health failure in the prevention of neural tube defects: time to abandon the tolerable upper intake level of folate. Wald et al, 2018 Public Health Reviews 39:2
  9. Folic acid and vitamin B12 fortification of food for preventing neural tube defects in Europe. Turner, 2018 BMJ Letters
  10. Centres for Disease Control and Prevention – accessed online October 2018