Author | Chuan Zhi Xiao Hong Lou: Zhang Yue
Source｜Medical World Obstetrics and Gynecology Channel
Thanks to years of popular science education and the guidance of doctors, it is now common knowledge that folic acid supplementation is necessary during both the preconception and pregnancy periods.
As a medical professional, while I am overjoyed, I also have concerns: some businesses are exaggerating the benefits of folic acid and demonizing the harms of not supplementing it to achieve ulterior commercial interests, which is detrimental to the public's correct understanding of folic acid. In order to unveil the mystery of this "pregnancy miracle drug" and reveal the truth about folic acid—neither mystifying nor demonizing it—let's explore the truth about folic acid today.
1
What is folic acid?
Folic acid, also known as vitamin B9, is a water-soluble vitamin that the human body cannot synthesize and must obtain from food. It participates in DNA synthesis and metabolism, playing a crucial role in cell division and growth, as well as the synthesis of nucleic acids, amino acids, and proteins. Folic acid deficiency in pregnant women can lead to birth defects such as low birth weight, cleft lip and palate, heart defects, and neural tube defects in the fetus.
According to the 2016 Chinese Dietary Guidelines, we recommend that women of childbearing age supplement with 400 micrograms of folic acid daily (equivalent to one folic acid tablet) starting three months before conception and continuing throughout the entire pregnancy [1]. In addition, the Chinese government has long included folic acid supplementation in basic public services, and women of childbearing age can obtain free folic acid tablets from the government at their community center without needing to purchase them separately.
Actually, folic acid is widely found in both plant and animal foods, especially in yeast, liver, and leafy green vegetables. Since folic acid is so common, why do we need to supplement it?
2
If we have natural folic acid, why do we need to supplement it?
The reason is that natural folic acid is extremely unstable and easily oxidized by sunlight and heat. Therefore, the human body can not obtain much folic acid from food. In addition, the first trimester (3-6 weeks) is a critical period for the differentiation of the fetal organ system, and cell growth and division are very vigorous. Therefore, pregnant women need much more folic acid than normal people.
Therefore, as early as the beginning of 1990, the U.S. Public Health Service and the Centers for Disease Control and Prevention recommended that all women planning to conceive take a daily supplement containing 0.4-0.8 mg of folic acid to prevent neural tube defects in the fetus. [2]
However, due to the deep-rooted belief that "all medicines have some toxicity," it was not long before people questioned the safety of long-term folic acid use: In the mid-1990s, three studies showed that long-term folic acid use could lead to an increased rate of miscarriage in pregnant women. [2]
This sparked a fierce debate, with scientists flocking to investigate whether folic acid is harmful.
Ultimately, a study in China involving 23,806 pregnant women found that daily folic acid intake did not increase the risk of miscarriage. Meanwhile, a multicenter trial in Brazil also reported no difference in miscarriage rates between the high-folic acid (4 mg/day) and low-folic acid (0.4 mg/day) groups. [3-4] More interestingly, a 2018 article published by the American Society for Reproductive Medicine even found that women who took folic acid before or during pregnancy had a lower risk of miscarriage! [2]
Based on the evidence we have, we can conclude that folic acid supplementation before and during pregnancy does not increase the risk of miscarriage, but rather increases a woman's chances of getting pregnant and maintaining a pregnancy.
3
Is more folic acid always better? Of course not!
Existing studies have confirmed that high doses of folic acid can produce toxic side effects, interfere with zinc absorption, and lead to intrauterine growth retardation in fetuses and low birth weight in newborns.
Excessive folic acid supplementation may also mask early symptoms of vitamin B12 deficiency, leading to irreversible neurological damage in patients with megaloblastic anemia who have both folic acid and vitamin B12 deficiency. In addition, excessive folic acid can interfere with the effects of anticonvulsant drugs and induce seizures. [5]
For the sake of their baby's health, expectant mothers must carefully follow their doctor's advice. They must not neglect folic acid supplementation due to laziness, but of course, they should not take too much folic acid and should take it according to the dosage recommended by their doctor.
The health of a pregnant woman and her fetus requires the joint efforts of the pregnant woman, her family, and doctors. In addition to regular prenatal checkups and advice from doctors, pregnant women also need to focus on a balanced and reasonable diet, moderate exercise, and a regular sleep schedule to nurture a healthy baby. We will continue to discuss how to supplement nutrition during pregnancy in Part 2!
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