Wednesday, May 25, 2016

Excess Folate and Vitamin B12 levels in pregnancy linked to Autism.

 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 syndromefragile 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 [= .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 [= .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 [< .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.

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