Neural Tube Defects - what are they, why does it matter, and what’s the deal with Folate?
Co-Written by Megan Churchill, Dietetics Student.
If you’re trying to conceive, or pregnant, you’ve probably been told to take a folic acid supplement - But what is that and why is it so important?
Folic Acid vs Folate:
Folic acid is the synthetic form of folate, a B vitamin (1). Folic acid is found in supplements, or enriched foods, while folate is found naturally in foods (1). During pregnancy, folate helps to form and close your fetus’ neural tube (1). However, the neural tube closes approximately 4 weeks after conception, a time when very few, if any, people know that they are pregnant . If the folate content of your diet is inadequate you are at risk for a folate deficiency, which could lead to Neural Tube Defects (NTD) in your unborn child.
Both the World Health Organization (WHO), and Centers for Disease Control and Prevention (CDC) recommend that women who can become pregnant, and/or are trying to conceive should take a folic acid supplement of 400 micrograms daily to prevent neural tube defects (1,2). It is also a good idea to incorporate foods with a high folate content into your diet.
Some women may require higher amounts of folic acid, but it’s best to discuss this with your health care team.
High folate containing foods (3):
Spinach
Asparagus
Brussel Sprouts
Avocado
Legumes such as black-eyed peas, or kidney beans
Mustard greens
Broccoli
As well, in Canada we have a folic acid enrichment program where 140 micrograms are added into every 100 grams of bread, breakfast cereals, flours, pasta, and rice (3).
So, what is a neural tube defect?
The neural tube is a structure that forms at 4-6 weeks in an embryo, and later goes on to form the spinal cord, spine, brain, and skull.
A neural tube defect is when the fetus’ neural tube doesn’t fully close. There are two types of neural tube defects:
Anencephaly where the neural tube does not close near the top, affecting the brain
Spina bifida, where the neural tube does not close near the bottom, affecting the spinal cord (4,5).
First, let’s talk about anencephaly. Anencephaly is a NTD where the baby is born lacking parts of their brain, and skull, and is the most serious neural tube defect. Anencephaly can be detected during pregnancy, or immediately after birth, and unfortunately there is no cure, and will likely be fatal (4).
Spina bifida is a neural tube defect where there is an opening in your babies’ spinal cord, but it can be corrected within 24 hours of birth. However, it is still likely that there will be irreversible nerve damage (5).
Both anencephaly and spina bifida are very serious, and life-threatening pregnancy complications. It’s important to know about both, because we can significantly reduce the risk of these conditions by optimizing our nutrition prior to conceiving.
If you have had recurrent miscarriages, it might be worth checking into your folate status, as NTD’s and inadequate folate is one of the main reasons for unsuccessful pregnancies.
So if folic acid is a synthetic version of Folate - why not just take a folate supplement?
Well - it’s complicated.
You can take an active folate supplement - check the ingredients label for Folinic Acid or 5MTHF, and in theory this would play the same role as a Folic Acid supplement, but the issue is that there are no randomized control trials looking at the effect of either of these more active forms of folate on preventing neural tube defects (NTD) - all the research is based on folic acid supplementation. There also probably never will be research on this, as it would be super unethical to do a trial of something we know works to prevent NTD’s, against something that may or may not. It’s already hard enough to get any research on pregnant women approved! Because of this, we can’t say for 100% certain that it is folate itself that is preventing NTD’s or a combination of folate and something else to do with the synthetic folic acid.
I’ve heard some people can’t metabolize folic acid?
This is true. When folic acid is consumed, an enzyme (MTHFR) converts it to the ‘active’ form of folate. However, some people carry a genetic mutation that can decrease the activity of this enzyme. Women who are homozygous for this mutation (have 1 copy of the mutation from both parents), may have up to a 70% loss of function of the MTHFR enzyme, meaning that they may not be able to efficiently convert folic acid to the active form of folate needed (6). This can lead to a higher risk of NTD’s, subfertilty, or issues with unmetabolized folic acid accumulating in the body. For these women, it is recommended to take the active form of folate in supplements folinic acid of 5MTHF).
It’s hard to know exactly how common this mutation is, as it’s not often tested for, but its thought that approximately 2-16% of women will be homozygous for the gene mutation.
What does this mean, practically speaking? Well, if you’ve tested positive for MTHFR mutations, or if you have experienced recurrent miscarriage and haven’t been tested for MTHFR but have been taking folic acid, it’s worth considering a supplement that has folinic acid or 5MTHF. Otherwise, it’s important to make sure you are getting adequate amounts of folic acid, AND natural folate. You can get both forms from food, and that should always be your priority. If you are not sure which supplement is right for you, make an appointment to talk more!
References
1. Center for Disease Control and Prevention. Folic Acid [Internet]. Centers for Disease Control and Prevention. 2018 [cited 2021Feb16]. Available from: https://www.cdc.gov/ncbddd/folicacid/about.html
2. World Health Organization. Periconceptional folic acid supplementation to prevent neural tube defects [Internet]. World Health Organization. 2019 [cited 2021Feb16]. Available from: https://www.who.int/elena/titles/folate_periconceptional/en/
3. National Institutes of Health. Office of Dietary Supplements - Folate [Internet]. NIH Office of Dietary Supplements. U.S. Department of Health and Human Services; 2020 [cited 2021Feb16]. Available from: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/
4. Centers for Disease Control and Prevention. Facts about Anencephaly [Internet]. Centers for Disease Control and Prevention. 2020 [cited 2021Feb16]. Available from: https://www.cdc.gov/ncbddd/birthdefects/anencephaly.html
5. Morrow K, Raymond JL. Krause and Mahans’s food and the nutrition care process. 15th ed. St. Louis: Elsevier; c2021.
6. Goldblatt, J., MTHFR genetic testing: Controversy and clinical implications. Men’s Health, 2016. 45(4): p. 237- 240
