Vitamin D Could Explain Why Autism Is Three Times More Common in Boys

A deficiency in vitamin D on the mother’s side could explain why autism spectrum disorder is three times more common in boys, say Queensland Brain Institute researchers.

In their latest study, Professor Darryl Eyles and Dr. Asad Ali found vitamin D deficiency during pregnancy caused an increase in testosterone in the developing brain of male rats.

Increase in testosterone in the brain 

“The biological cause of autism spectrum disorder (ASD) is unknown but we have shown that one of the many risk factors—low vitamin D in mothers—causes an increase in testosterone in the brain of the male fetuses, as well as the maternal blood and amniotic fluid,” Professor Eyles said.

“In addition to its role in calcium absorption, vitamin D is crucial to many developmental processes.

“Our research also showed that in vitamin D-deficient male fetuses, an enzyme which breaks down testosterone was silenced and could be contributing to the presence of high testosterone levels.”

Vitamin D is critical in brain development

Professor Eyles’ previous research has shown that vitamin D plays a critical role in brain development and that giving vitamin D supplements to mice during pregnancy completely prevented autism-like traits in their offspring.

Co-author Dr. Ali said that excessive exposure of the developing brain to sex hormones like testosterone was thought to be an underlying cause of ASD, but the reasons remained unclear.

“Vitamin D is involved in pathways controlling many sex hormones,” Dr. Ali said.

“When the rat mothers were fed a low vitamin D diet, it caused male fetal brains to have high levels of exposure to testosterone.”

Time to study more risk factors for ASD

Professor Eyles said the study was the first to show that a known risk factor for ASD alters testosterone in both the fetal brain and the mother’s blood — one possible contributor to why ASD is more prevalent in males.

“We have only studied one risk factor for ASD — vitamin D deficiency during development — our next step is to look at other possible risk factors, such as maternal stress and hypoxia – lack of oxygen – and see if they have the same effect,” he said.

Reference: “Developmental vitamin D deficiency increases foetal exposure to testosterone” by Asad Amanat Ali, Xiaoying Cui, Renata Aparecida Nedel Pertile, Xiang Li, Gregory Medley, Suzanne Adele Alexander, Andrew J. O. Whitehouse, John Joseph McGrath and Darryl Walter Eyles, 10 December 2020, Molecular Autism.
DOI: 10.1186/s13229-020-00399-2

This research is published in Molecular Autism and was a collaboration with The University of Western Australia’s Dr Andrew Whitehouse and funded by the National Health and Medical Research Council Australia and Queensland Centre for Mental Health Research.

Autism Spectrum DisorderNeuroscienceNutritionPopularUniversity of QueenslandVitamins
Comments ( 12 )
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  • Richard Turner

    If this is correct, there should be a seasonal variation in the incidence of births of autistic males. Expectant mothers exposed to lower levels of sunlight during pregnancy at the developmental stage when D deficiency has the most impact on their male babies would be more likely to give birth to an autistic baby. Is there a seasonal variation in the births of autistic males?

    • Robert M Saul

      I I have been saying this for years looking at the increase in autism since you do meteorologists told us to stay out of the Sun it seemed very obvious to me I did not know the biochemistry

  • William R Moore

    So, is there a similar effect in female fetuses? If so, does it result in high testosterone in the female fetus brain or, one of the female hormones? If it does cause high testosterone levels in female fetus brains, could it be a link to female homosexuality or female to male transexuality? There once was a theory about high testosterone levels in the fetal brain leading to homosexuality. I don’t follow these topics very closely, so I’ll risk all the negative social reaction by posing the question…

  • Paul Wichman

    Sun tanning/exposure (without blocking topicals) has been recommended against for the past 25years courtesy of my profession. This has lead to a significant drop in vit d3 levels. Curious how the autism “epidemic” started at about the same time. I think we’ll see a drop in the amount of autism now that vitd3 is being encouraged in pregnant women. Pwichman md

    • William Jones

      This comment prompts me to think of other correlations, including the onset of the low fat diet (beginning 30 years ago).

  • Holly Nires

    I know a family which has 5 autistic children both male and female. The autism is divided between 3 different adult family members. Is this a genetic trait or a vitamin d deficiency?

  • Holly

    I know of a family consisting of 3 adults and 5 autistic children spread between all 3 families. Is this a generic situation or a vitamin d deficiency? The children are boys and girls.

  • B

    Wow! I have 2 autistic males. 1st born since 4yrs old has had feminine characteristics (high functioning), the other son, no feminine traits, (not high functioning).

  • Ron Booth

    Vitamin D3 & Vitamin K2 also work well together putting Calcium in the right place. Also clearing your arteries of plaque.

  • Margaret watson

    Wow I have four grandchildren. A girl first which is perfectly normal.. Then second a boy.. Which have autism.. My third is a girl perfectly normal..four a boy which was born early weight only 1pd 6oz.
    I have went out of my mind wondering why? My boy’s was sick and the girls wasn’t

  • Critical Thinking

    Thankfully, the EU is moving to require sex and gender data collection in the research it funds. We have too many conditions, plaguing too many people, to allow political or social “correctness” to interfere with scientific research. The US needs to catch up with the EU in this area.

    Gender is not a fluid aspect of the body, as some would like us to believe. If something lands an individual somewhere between the binary sexes, something disrupted normal development and there is nothing inherently evil or discriminatory in researching that cause.

  • Eugene Barufkin

    Wow! What a great study and discovery.
    With vast computer data bases, I hope more info will come rapidly.
    D3 is essential for everyone, especially seniors.
    Keep you levels high in winter.
    All annual blood work checkups should include D3 levels.
    There should not be an extra charge.
    Good D3 levels save money by keeping people ‘more’ healthy.