Importance of vitamin B9 in pregnancy

What is vitamin B9?

Vitamin B9 is also known as folic acid. This vitamin belongs to the group of water-soluble vitamins, meaning that it is soluble in water. In general, this vitamin helps reduce fatigue and contributes to the proper functioning of the immune system. It also plays a role in the process of cell division and in the synthesis of amino acids, the building blocks of proteins.

What is the role of vitamin B9 during pregnancy?

Interest of vitamin B9 for the future mother

During pregnancy, vitamin B9 becomes essential. It is indeed the star of women wanting a child or being pregnant. This vitamin is indeed essential to the formation of the placenta and the growth of the uterus during pregnancy.

Importance of vitamin B9 for the fetus

It is also of great importance for the fetus itself. The nervous system of the fetus is established between the 3rd and 8th week of pregnancy, i.e. during the main trimester. Vitamin B9 is necessary for the closure of the neural tube, from which the whole nervous system of the baby will develop.

Risks of neural tube closure anomalies

If the vitamin B9 intake is not sufficient, there may be neural tube closure anomalies. In France, the incidence of this anomaly is 1.3 births in 1000. Folic acid intake should therefore not be neglected. It is even recommended to anticipate and ensure a good intake ideally 2 to 3 months before the beginning of the pregnancy. Therefore, as soon as you plan to have a child, it is important to ensure a good intake of vitamin B9.

Which food sources?

Several foods are particularly rich in folic acid. For example, chicken liver contains no less than 578 µg per 100g of product. Vitamin B9 is also present in many green leafy vegetables, hence the name “folate”. Romaine lettuce (136µg/100g), spinach (125µg/100g) or asparagus (101µg/100g) are good sources. Finally, sunflower seeds (254µg/100g) or flax seeds (93.7µg/100g) can easily be integrated into your diet.

Which form of vitamin B9 should be favored in food supplements?

A genetic mutation at the origin of a low assimilation

For the benefits of vitamin B9 to be perceived by the body, it is necessary that folates be converted by the body into an assimilable form. This conversion is carried out by a specific protein, called MHTFR (methyl tetra hydro folate reductase) enzyme. For genetic reasons, mutations can affect this enzyme, resulting in a reduction of up to 75% of its synthesis. Thus, due to its limited presence in the body in people with this mutation, folic acid is not sufficiently transformed into a form that can be used by the body.

Different forms of vitamin B9 with varying effectiveness

Knowing the importance of vitamin B9, especially during pregnancy, and the existence of mutations that can limit the intake of vitamin B9, laboratories have developed forms of vitamin B9 that can be directly assimilated. These patented forms are directly bioactive and usable by the organism even if the person carries a mutation on the MHTFR. On the packaging, this patented vitamin B9 can be recognized by its name: methyl-tetrahydrofolate or methylfolate. The only disadvantage of these specific forms is the price, which is about 500 times higher than synthetic folic acid compounds. 


Vitamin B9 offers numerous health benefits such as a reduction in fatigue, a contribution to the proper functioning of the immune system, etc. It is also the flagship vitamin for women wishing to have a child or being pregnant. This vitamin allows the development of the uterus and the placenta during pregnancy, but also guarantees a good closure of the neural tube of the fetus, precursor of the whole nervous system. Thus, in most European countries, a vitamin B9 supplementation is recommended before pregnancy. Green leafy vegetables are very good sources of vitamin B9. When choosing your pregnancy food supplement, check that the vitamin B9 is in methylfolate form. This guarantees that your body will assimilate it properly, even if you have a mutation in the MHTFR conversion enzyme.

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