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The water-soluble vitamin B9, or folic acid, is essential for the erythrocytes’ formation and healthy cell growth and function. Sufficient amounts of this vitamin during pregnancy have been proven to promote cell proliferation and prevent defects in the child’s nervous system. However, in the “post-fortification era,” concerns among healthcare professionals are rising regarding the excessive consumption of synthetic forms of folic acid (FA) by mothers.
American researchers have compiled what is known about the impact of excessive FA intake during pregnancy. The review was published in the Nutrients journal.
The Importance of Folic Acid
Folic acid is a highly important vitamin. It is prescribed during pregnancy and lactation to reduce the risk of neural tube defects, improve cardiovascular and reproductive health. FA deficiency in the mother increases the risk of excessive or insufficient weight and high blood pressure in the child.
FA in the second and third trimesters has lasting benefits for the offspring’s neurocognitive development up to 11 years old. These benefits include emotional intelligence, verbal reasoning, semantic processing, verbal-executive and motor functions, attention, communication, and social competence. Additionally, the authors included a study conducted in Norway in the review. It showed that taking FA four weeks before pregnancy and continuing for 12 weeks afterward protects against autism spectrum disorders (ASD).
Synthetic Folic Acid and the Risk of Overdose
Folic acid is found in certain foods, including vegetables, legumes, poultry meat, egg yolks, some berries, and nuts. However, the availability of fortified foods and supplements has significantly increased FA level in blood serum.
Due to food fortification and the relatively high use of multivitamin supplements, overall folate levels have significantly increased on a population-wide scale. Recent studies raised concern regarding the adverse effect of maternal folate excess.
Study Authors
Current recommendations for healthy women are 400 mcg/day before pregnancy, 600 mcg/day during pregnancy, and 500 mcg/day during lactation. However, in the presence of a folate deficiency, a doctor may increase the daily dose.
Consequences of Excess Folic Acid
A recent US study identified a “U-shaped” association between the risk of ASD and maternal multivitamin supplement intake. This means that ASD risk is highest when there is FA deficiency or when its level exceeds the norm.
Since such experiments are ethically impossible in humans, many studies on FA high doses have been conducted in mice. The results of some of these studies indicate that mice given a moderate dose of FA had more genetic changes. Changes occurred in various genes depending on gender, leading to differentiated effects in the placenta and the brains of mice before and after birth. There are indications that FA may influence brain development at an early stage of life but lead to long-term changes.
Excess folic acid has been associated with decreased placental and embryo weight, smaller hippocampal area, and increased weight in males, but not in females. Additionally, studies have shown the impact of FA high levels on nervous system development. Among the adverse effects are worsened short-term memory, hyperactive and repetitive behavior, and increased anxiety in mice.
Scientists’ Conclusions
The results of various studies varied, but there is clear evidence that excessive FA consumption by mothers can have long-term effects on the physical and cognitive development of the offspring. Therefore, it is crucial to monitor folates level in the blood before taking additional supplements even during the planning stage of pregnancy.
At the same time, scientists believe that further research among humans is needed to study the gene-related impact discussed in the article. According to scientists, attention should also be paid to new forms of FA that may mitigate the potential harm of existing supplements.
