Ottawa Hospital study to explore link between folic acid dosage, autism
Two Ottawa-based researchers have been awarded a $9.8-million grant to study the link between taking high doses of folic acid during pregnancy and giving birth to a child with autism.
Folic acid, the vitamin form of folate — a B vitamin naturally found in fruits and vegetables — is known to reduce certain types of birth defects, in particular spina bifida.
Health Canada currently recommends that all pregnant women take 0.4 milligrams of folic acid per day. But a recent study by the Johns Hopkins Bloomberg School of Public Health linked excessively high levels of folic acid in pregnant women to an increase in children being born with autism.
Researchers found that women who had four times the "adequate" amount of folic acid had double the risk of their babies developing autism spectrum disorder.
"We have long known that a folate deficiency in pregnant mothers is detrimental to her child's development. But what this tells us is that excessive amounts may also cause harm," said one of the study's authors, Dr. Daniele Fallin in a statement released in May.
Ottawa study seeks 'definitive answer'
"The Johns Hopkins study was a surprise to a lot of us," said Dr. Mark Walker, department chief of obstetrics, gynecology and newborn care at The Ottawa Hospital and a professor at the University of Ottawa, as well as one of two researchers leading the study.
Walker and his colleague Dr. Shi Wu Wen have been studying the effects of folic acid for 15 years. Their current work focuses on whether taking high doses of the supplement can help prevent preeclampsia — the leading cause of maternal death in the developed world — in pregnant women.
In 2008 they published an observational study of 2,950 mothers in Ottawa and Kingston, Ont. They found taking folic acid in the early second trimester lowered a mother's risk of preeclampsia by 63 per cent.
In 2011 the team recruited 2,464 mothers at risk of preeclampsia from five different countries around the world. Half of the mothers took a high dose of folic acid throughout their pregnancy, and the rest stopped taking it after the first trimester. The results of this study will be published next year.
Now Walker and Wen intend to follow the children of those women and assess their neurological development.
"We'll definitely have the answer in the best possible study designed to see the safety and long-term effects of higher dose folic acid," Walker said.
Too much of a good thing?
Walker says because folic acid is known to be so effective in preventing birth defects, sometimes pregnant women take larger doses of the supplement.
But Walker says the attitude that because a little folic acid is good, the idea that "more is better and a ton fantastic" isn't necessarily safe for women at low risk of developing complications in pregnancy.
In some parts of the world women take between 5 to 10 milligrams of folic acid a day, Walker found during the research.
"We really don't know the safety of these doses. We'll be able to, at the end of this [study], really say with confidence ... whether or not that level of folic acid is first of all safe, is it beneficial, or is it harmful."
Walker says pregnant women should continue to take low doses of folic acid as recommended by their doctors to help prevent birth defects.
