Folic acid and pregnancy: why it's important

1. What is folic acid?

Vitamin B9, known as folate in its dietary form , is not produced by the body and must therefore be obtained through food (leafy green vegetables, liver, etc.). However, this natural form is sensitive to oxidation, air, and heat, resulting in a loss of approximately 75% between harvesting and consumption. Furthermore, its bioavailability (the proportion actually absorbed and used by the body) is only about 50%. To compensate for this instability, a more stable synthetic form has been developed: folic acid , which has a bioavailability of up to 85%. Finally, both folate and folic acid must be converted by the body into their active form, 5-methyltetrahydrofolate (5-MTHF) , in order to fulfill their physiological functions.

2. Vitamin B9, what is its role during pregnancy?

Folic acid is involved in DNA synthesis, cell division, and the development of the nervous system. During pregnancy, it becomes essential from the first weeks because this is when the neural tube of the future baby, which will become the brain and spinal cord, begins to form.

Insufficient intake can lead to serious birth defects such as anencephaly (absence of a brain) and spina bifida (failure of the spinal column to close). These abnormalities often occur even before pregnancy is confirmed, hence the importance of early supplementation, ideally starting as soon as conception is desired.

A. Baby project, when to take folic acid?

Health authorities recommend a daily supplementation of 400 µg of folic acid from the moment pregnancy is desired (or 5 mg/day in case of a history of neural tube closure defects).

EFSA in 2017 and then ANSES in 2021 reassessed the satisfactory intake for women likely to become pregnant at 600 µg/day.

This preventive measure is all the more justified given that 75% of women of childbearing age have folate intakes below nutritional recommendations.

3. Why do some women have difficulty absorbing folic acid?

To exert its beneficial effects, synthetic folic acid (the form commonly used in supplements and medicines) must be transformed by the MTHFR enzyme into its active form: 5-MTHF (5-methyltetrahydrofolate).

However, approximately 1 in 2 women have mutations in the MTHFR gene that reduce this conversion capacity. In this case, conventional folic acid is poorly metabolized, compromising the effectiveness of supplementation.

A. Which folic acid should I choose for good absorption?

To bypass the folic acid assimilation defects linked to this mutation, it is possible to directly use the 5-MTHF form (active form of vitamin B9) which has better bioavailability.

This article is for informational purposes only and does not replace a consultation or advice from your doctor.