Autism
spectrum disorder (ASD) is a neurodevelopmental condition characterized by
social impairment, abnormal communication and repetitive or unusual behavior.
It is one
of the rapidly growing developmental disorder in USA, now affecting 1 in 68 children and
1 in 42 boys. Boys are nearly 5 times more likely to develop Autism than girls
and there is no medical detection , screening or cure for Autism.
Some of the
known risk factors for Autism spectrum disorder (ASD) are older age of parents,
prematurity, LBW, previous sibling being diagnosed with ASD, certain genetic
or chromosomal conditions like Down syndrome, fragile X syndrome,tuberous
sclerosis. It also co-occurs with other developmental, psychiatric,
neurologic, chromosomal, and genetic diagnoses.
It is well
established fact that adequate levels of folic acid are necessary for
preventing neural tube defects (NTDs) and pregnant women are advised to start
folic acid supplementation as soon as they start planning their pregnancy and
through first trimester. In US breads, cereals and other breakfast items are
fortified with folic acid.
But, as the
saying goes ‘excess of everything is bad’, so is the case with excess of folic
acid in blood during the antenatal period. A recent study presented at
the 2016 International Meeting for Autism Research in Baltimore have
linked excess folic acid and B12 to Autism. The study is also published in
April issue of The
FASEB Journal.
The
researchers analyzed data from nearly 1,391 mother-child pairs in the Boston
Birth Cohort, which is an ongoing longitudinal prospective birth cohort study
consisting of low-income urban, primarily minority mother-offspring pairs. The
children were followed from birth through childhood between 1998–2013.
Maternal Blood samples were collected 48-72 hours post delivery and analyzed
for plasma folate, Vit B12 and homocysteine levels.
A total of
107 infants were diagnosed with autism, Asperger syndrome, and/or pervasive
developmental disorder not otherwise specified and were categorized as having
ASD.
According to
the World Health Organization folate levels between 13.5 and 45.3 nanomoles per
liter represent adequate amount of folate for a woman in her first trimester of
pregnancy. But, well established threshold for Vit B12 is yet to be researched
at.
The
researchers found that one in 10 of the study subject had an excess amount of
folate (more than 59 nanomoles per liter) and six percent had an excess amount
of vitamin B12 (more than 600 picomoles per liter).
It is not
known that why some women have such high levels of folate and Vit B12. The
researchers link it with diet, genetic makeup for metabolizing folates and
supplementation or a combination of all these.
The findings
from this study are still very premature and not been peer-reviewed. The data
has to be looked at closely and multiple studies are required before a
recommendation can be made.
Principal
investigator Daniele Fallin, PhD, director, Wendy Klag Center for Autism and
Developmental Disabilities, John Hopkins Bloomberg School of Public Health,
said during a press briefing. "When we looked at the vitamin
supplementation evidence, we saw what our colleagues see ― that indeed, women
who took vitamin supplementation during pregnancy had a lower risk of autism in
their children and that is very consistent with the literature."
"But
when we looked at women who had excessively high levels of folate, we saw that
very high levels of folate in the mother were responsible for about a twofold
increased risk for autism in their child [P = .007], and when we
looked at B12, women who had excessively high levels of B12 had a threefold
increased risk for their child to have autism [P = .001], while
women who had extreme levels of both folate and vitamin B12 had a 17.6 times
greater risk of having their child diagnosed with an ASD [autism spectrum
disorder] later on [P < .001]," she added.
"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. We must aim for optimal levels of this important
nutrient," said Fallin.
This study
gives us some important future research topics about how much folic acid
supplementation is enough and what constitutes the excess and part played by
genetics and diet.
"So for
now, the public health message is, supplementation is good, but there may be a
subset of women whose levels are extremely high, and these extreme levels may
be harmful."
Women should
be cautioned about randomly popping vitamin supplements in pregnancy until
further larger study data is available.
References:
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