Vitamine D et autisme

Autism and vitamin D

There has been a dramatic and concerning increase in the rates of autism spectrum disorder (ASD) over the last 30 years and experts believe the rates will continue to increase.

Due to damage gut microbiome and insufficient level of vitamin D.

What's Causing the Rapid Rise in Autism?

Disturbingly, the CDC (Center for Disease Control) also reports that an astounding 1 in 6 children have some form of developmental disability, ranging from speech and language impairments to more serious intellectual disabilities, including [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien].

Based on the fact that the human brain contains vitamin D receptors, this suggests vitamin D is important for proper brain development and function. Research is now starting to validate this hypothesis.

The study, which has garnered wide international media attention,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]^,[Vous devez être inscrit et connecté pour voir ce lien]  is the first study examining the association between gestational vitamin D deficiency and autism or autism-related traits in general population samples. According to the authors:

"Those who were 25OHD [25-hydroxyvitamin D] deficient had significantly higher (more abnormal) SRS [Social Responsiveness Scale] scores.”

All of the mothers enrolled in the study gave birth between April 2002 and January 2006. The children were then followed until the age of 6.

Vitamin D levels were assessed at mid-gestation (between 18 and 25 weeks) from maternal blood samples, and cord blood at birth.

Vitamin D deficiency was defined as a 25OHD concentration below 10 nanograms per milliliter (ng/mL) or 25 nmol per liter (nmol/L). A vitamin D level between 10 to 19.96 ng/mL (25 to 49.9 nmol/L) was deemed insufficient, while a level of 20 ng/mL (50 nmol/L) or more was sufficient.

Other leading vitamin D researchers have produced compelling evidence showing that anything below 40 ng/mL (100 nmol/L) is insufficient, and anything below 20 ng/mL (50 nmol/L) is a deficiency state.

Editor’s note: According to my reading, optimal state is between 30 - 35 ng/mL (75 - 88 nmol/L).

How does it work?
Biological scientist Rhonda Patrick, Ph.D., has published two papers[Vous devez être inscrit et connecté pour voir ce lien]^{,[Vous devez être inscrit et connecté pour voir ce lien]} that present a truly elegant hypothesis for how vitamin D may influence autism. To understand why vitamin D plays such an important role in brain function (and dysfunction), it's important to understand that vitamin D actually gets converted into a steroid hormone (other steroid hormones include estrogen and testosterone).
As a steroid hormone, it regulates over 1,000 different physiological processes, and is thought to control at least 5 percent of the human genome. When you have enough vitamin D in your body, it binds to vitamin D receptors located throughout your body, thereby acting like a key that opens the proverbial door.
The vitamin D receptor complex can go deep inside the DNA, where it recognizes the tell-tale sequence of code that instructs the vitamin D receptor complex to either turn the gene on (making it active), or off (making it inactive).

Patrick's research identified a vitamin D-regulated gene that encodes a foreign enzyme called tryptophan hydroxylase (TPH). TPH is responsible for converting tryptophan (which you get from dietary protein) into serotonin, a neurotransmitter involved in both mood regulation and brain development.

You have two different TPH genes in your body — one in your brain and one in your gut. The one in your brain makes serotonin in the brain, and the one in your gut converts tryptophan into serotonin in the gut, and the latter cannot cross the blood-brain barrier to get into your brain.

This is an important point because, while many understand that the majority (about 90 percent) of the serotonin in your body is produced in the gut and not the brain, the thinking has been that the gut serotonin will automatically influence brain function.

Since it's unable to cross the blood-brain barrier, this is not the case. The two serotonin systems are completely separate. Your gut serotonin plays a role in blood coagulation, which is an important benefit. On the other hand, too much gut serotonin will activate T-cells, causing them to proliferate and promote inflammation.

Since the publication of Patrick's first paper[Vous devez être inscrit et connecté pour voir ce lien] in 2014, an independent group at the University of Arizona has biochemically validated her findings, confirming that vitamin D does activate the tryptophan hydroxylase 2 (TPH2) gene in a variety of neuronal cell types.

[Vous devez être inscrit et connecté pour voir ce lien]

Vitamin D is crucial during pregnancy for many other reasons as well. Research has shown that children born of women with adequate levels of vitamin D have a lower risk for [Vous devez être inscrit et connecté pour voir ce lien] (MS) and other autoimmune conditions like inflammatory bowel disease and type 1 diabetes, in childhood and later life.

A recent Danish study[Vous devez être inscrit et connecté pour voir ce lien]^{,[Vous devez être inscrit et connecté pour voir ce lien]} showed that newborns with vitamin D levels above 20 ng/mL (50 nmol/L) were 47 percent less likely to develop MS by the age of 30 compared to those with vitamin D levels below 12 ng/mL (30 nmol/L) at birth. MS is a chronic, neurodegenerative disease of the nerves in your brain and spinal column, caused through a demyelization process. It has long been considered a "hopeless" disease with few treatment options.

A study[Vous devez être inscrit et connecté pour voir ce lien]^{,[Vous devez être inscrit et connecté pour voir ce lien]} presented at the annual meeting of the American Association of Neuromuscular and Electrodiagnostic Medicine[Vous devez être inscrit et connecté pour voir ce lien] (AANEM) in 2014 showed that vitamin D deficiency is surprisingly prevalent among those diagnosed with MS and other neuromuscular conditions. Here, vitamin D deficiency was defined as a 25OHD3 level of 30ng/mL (75 nmol/L) or less.

Of patients diagnosed with a neuromuscular condition, 48 percent were deficient in vitamin D. Only 14 percent were above "normal," which here constituted a vitamin D level of 40 ng/mL (100 nmol/L). According to one of the authors:

 "While the connection between vitamin D deficiency and neurologic disease is likely complex and not yet fully understood, this study may prompt physicians to consider checking vitamin D levels in their patients with neurologic conditions and supplementing when necessary."

Luc a écrit:=> Les recherches de Rhonda Patrick ont identifié un gène régulé par la vitamine D qui code une enzyme appelée tryptophane hydroxylase (TPH). TPH est responsable de la conversion du tryptophane (acide aminé que vous obtenez via l’alimentation) en sérotonine, un neurotransmetteur impliqué dans la régulation de l'humeur et le développement du cerveau.

Vous avez deux gènes TPH différents dans votre corps, un dans votre cerveau et un autre dans votre intestin. Celui de votre cerveau produit de la sérotonine dans le cerveau, et celui dans votre intestin convertit le tryptophane en sérotonine dans l'intestin...

...Les deux systèmes de sérotonine sont complètement séparés. La sérotonine  de votre intestin joue aussi un rôle dans la coagulation du sang, ce qui est un avantage important. D'autre part, trop de sérotonine intestinale va activer les cellules T, les faisant proliférer et favoriser l'inflammation.