Women who plan on becoming pregnant are told they need enough of the nutrient folate to ensure proper neurodevelopment of their babies.
However, new research from the Johns Hopkins suggests there could be serious risks in having far too much of folate.
The researchers found that if a new mother has a very high level of folate right after giving birth – more than 4 times what is considered adequate – the risk that her child will develop autism doubles.
Very high vitamin B12 levels in new moms are also potentially harmful, tripling the risk that her offspring will develop autism.
If both levels are extremely high, the risk that a child develops autism increases 17.6 times.
Folate, a B vitamin, is found naturally in fruits and vegetables, while the synthetic version, folic acid, is used to fortify cereals and breads in the United States and in vitamin supplements.
The preliminary findings were presented at the 2016 International Meeting for Autism Research in Baltimore.
Folate is essential in cell growth and promotes neurodevelopmental growth. Deficiencies early in pregnancy have been linked to birth defects and to an increased risk of developing autism.
And despite this push to ensure women get adequate folate, some women still don’t get enough or their bodies aren’t properly absorbing it, leading to deficiencies.
The Centers for Disease Control and Prevention says that one in 4 women of reproductive age in the U.S. have insufficient folate levels. Levels are not routinely monitored during pregnancy.
Autism spectrum disorder is a neurodevelopmental condition characterized by social impairment, abnormal communication and repetitive or unusual behavior.
One in 68 children in the U.S. have the disorder, with boys 5 times more likely than girls to have it.
The causes remain unclear but research suggests the factors are a combination of genes and the environment.
For the study, the researchers analyzed data from 1,391 mother-child pairs in the Boston Birth Cohort, a predominantly low-income minority population.
The mothers were recruited at the time of their child’s birth between 1998 and 2013 and followed for several years, with the mother’s blood folate levels checked once within the first one to three days of delivery.
The researchers found that 10% of the women had what is considered an excess amount of folate (more than 59 nanomoles per liter) and 6% had an excess amount of vitamin B12 (more than 600 picomoles per liter).
A large majority of the mothers in the study reported having taken multivitamins – which would include folic acid and vitamin B12 – throughout pregnancy.
But the researchers say they don’t know exactly why some of the women had such high levels in their blood.
It could be that they consumed too many folic acid-fortified foods or took too many supplements.
Or it could be that some women are genetically predisposed to absorbing greater quantities of folate or metabolizing it slower, leading to the excess.
More research is needed, the scientists say, in order to determine just how much folic acid a woman should consume during pregnancy.
News source: Johns Hopkins Bloomberg School of Public Health.
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