Excess folic acid in pregnancy may increase risk of autism
The substance is just one of several factors that can contribute to the disorder, but the correct dosage is fundamental for the baby's neurodevelopment
Consumption of folate - or folic acid in its synthetic form - before and during pregnancy is essential to help close babies' neural tubes, which will form the central nervous system. The substance also prevents morphological problems such as anencephaly, cleft palate and cleft lip, but an excess of this vitamin (B9) can increase the risk of autism in children twice.
The conclusion comes from a study conducted by researchers at the Johns Hopkins Bloomberg School of Public Health in the United States, who analyzed 1,391 mothers and their children between 1998 and 2013. The level of folate in their blood was measured shortly after giving birth, and the children were followed up during this period.
The results, presented in 2016, indicated that mothers of autistic children had folate levels four times higher than adequate. The excess was found in one in ten participants.
"Excess folate acts in a very specific way, in the mechanism of hypermethylation of the DNA of the fetus, which can damage neurodevelopment. The excess can damage the genes that make up the maturation of the brain and cause some malformation, possibly developing autism or partial autism," explains Antonio Cabral, PhD in obstetrics from the Federal University of São Paulo (Unifesp) and professor of obstetrics at the Faculty of Medicine of the Federal University of Minas Gerais (UFMG).
Cabral makes it clear, however, that autism is caused by much broader reasons than this single factor. "There has to be a genetic predisposition and other factors. An excess of folate can have a different effect on someone else," he says.
Autism. Psychiatrist Andreas Stravogiannis, technical director of the Association of Friends of Autism (AMA), explains that autism is a neurodevelopmental disorder and has multiple causes. "There are genetic and environmental factors which, together with hereditary ones, can lead to the condition," he says.
Among the possible environmental causes, the specialist cites neonatal infections, problems in labor, malnutrition in the mother which can hinder the formation of the fetus, exposure to chemical or toxic substances during pregnancy or in the baby's first days of life, and premature birth.
Stravogiannis says that doctors and science are still wondering why such different factors would lead to autism - or any other neurological disorder. But he points out that not every mother who experiences one of these situations will have an autistic child.
"When a diagnosis of autism is made, the possible causes have to be investigated, but most of the time the patients don't have enough evidence to justify autism," explains the psychiatrist.
Recommendation continues. When the study was published, some doctors criticized the results. According to the critics, the researchers were being \'irresponsible\' and \'generating risks\' in mothers who, in fact, should continue taking the vitamin. In addition, a study published in 2013 in The Journal of the American Medical Association showed that the intake of folic acid by pregnant women reduced the risk of autism.
Antonio Cabral explains that, at the time, there was a warning that women were already ingesting folic acid in their diet. The substance can be found naturally in fruit and vegetables and is used to enrich flours. "What we shouldn't do is use it in high doses," she emphasizes. The intake of folic acid by pregnant women remains important.
Because they already consume the vitamin in food, even without knowing it, women who are pregnant or planning to have children should pay attention to the correct dosage when supplementing. The ideal, according to Cabral, is to take between 0.4 and 0.8 milligrams a day before becoming pregnant and in the first three months of pregnancy, following the recommendations of the World Health Organization (WHO) and Brazilian entities such as the Federal Council of Medicine (CFM) and the Brazilian Federation of Gynecology and Obstetrics Associations (Febrasgo).
This dose, however, can vary from one woman to another. "If a woman has any activity or habit that could reduce folic acid [in the body], such as smoking or intense physical activity, she can use it within this dosage or a little more. You have to talk to your doctor to see if it's excessive," says Cabral. A blood test that measures the amount of folate can also help with the correct prescription of the vitamin.
Absence or incorrect intake. In Brazil, 55.4% of women become pregnant without planning to, according to a study carried out by the National School of Public Health at the Oswaldo Cruz Foundation (ENSP/Fiocruz). In other words, they don't benefit from the positive effects of folic acid before conception. As well as helping with neurodevelopment and morphology, the vitamin helps with heart formation and, if taken in lower doses throughout pregnancy, prevents premature birth, says Cabral.
The risk of excess folate in the blood is not so difficult. Because it is a common vitamin, the substance is sold in pharmacies without the need for a doctor's prescription and distributed free of charge by the Unified Health System (SUS). In the latter case, it is purchased for various purposes, such as against anemia, and may be available in higher dosages than those indicated for pregnant women.
More studies. "Adequate supplementation is protective - this continues to be the case with folic acid," says Daniele Fallin, one of the authors of the Johns Hopkins Bloomberg study. However, the researchers say that more studies are needed to determine how much folic acid a woman should consume during pregnancy.
"Folic acid acts mainly on the neural tube in the first trimester. You'd have to see if they [the mothers] had high levels in that early period," says Stravogiannis, pointing to the fact that the study measured folate levels in the postpartum period. Amid the important benefits and possible risks of excess folate in pregnant women, the warning is for doctors and women to pay attention to the proper dosage of the substance.