Folic acid is a type of water-soluble B vitamin and is an indispensable nutrient during the embryonic development process. It can be ingested from food, but only a small amount can be stored in the human body, while the rest is excreted through urine.

Why is a folic acid deficiency bad?

A lack of folic acid in the early stage of embryonic development may result in neural tube defects and Down syndrome of the fetus, as well as increased risk of miscarriage and pregnancy-induced hypertension for the mother.

However, too much folic acid can also be harmful. It may increase the risk of obesity and insulin resistance in offspring, and mask the symptoms of vitamin B12 deficiency, thereby neglecting vitamin B12 supplementations and causing nerve damage. Excessive folic acid intake may also affect the absorption of zinc, which will cause problems such as fetal growth retardation.

How is folic acid metabolized?

In the human body, folic acid must be metabolized to 5-methyltetrahydrofolate by the key enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) before it can be utilized by the body. If the key enzyme gene is mutated, C677T and A1298C are the most tested MTHFR mutations, that is, the normal CC genotype mutates into the CT or TT genotype, folic acid utilization abilities will decrease, resulting in folic acid deficiency and abnormal pregnancy.

How to judge one's folic acid utilization ability?

"Folic acid utilization ability gene" detection can be used to measure one's folic acid utilization ability and detect the common mutation genotypes of MTHFR via the quantitative fluorescence PCR (polymerase chain reaction) method.

It has been reported that people in different genotypes have different folic acid utilization capabilities and require different amounts of folic acid supplementation. MTHFR gene CT heterozygotes and TT homozygotes account for about three quarters of the Chinese population, and according to the Guideline for the Prevention of Neural Tube Defects by Periconceptional Folic Acid Supplementation (2017), people of these types need to supplement more folic acid than those of the CC type.

Therefore, the following people should undergo "folic acid utilization ability gene" detection and receive timely supplements of folic acid so as to avoid abnormal pregnancy.

1. Women preparing for pregnancy;

2. Women who have given birth to a child with birth defects (especially with a neural tube defect);

3. Women with a history of unexplained spontaneous abortion, fetal malformation, or stillbirth.