Vitamin D deficiency is known historically to cause rickets in children and osteomalacia in adults. It is a steroid hormone with a cholesterol backbone and is fat soluble. Most intake occurs from sun exposure via the skin. Therefore, when a cohort of people such as those on the autism spectrum have low cholesterol and blood lipids, it is important to check vitamin D status. In the last 15 years more research has gone into vitamin D and studies show it goes far beyond bone health and is implicated in fighting infection as well. There are correlations between autistic behaviour, sun exposure of the mother during gestation, and the public health message to reduce sun exposure levels in the last 10-15 years. This is also the amount of time that incidence of the disorder have risen exponentially. (1)
A key feature of autism is dysregulated immune responses, meaning vitamin D could possibly be a remedy for this. A case controlled study of 122 autistic individuals showed that over 60% had low vitamin D status. (2) When supplemented for 3 months, 80% of them had improved behaviour, eye contact, and attention span. Vitamin D administration to rat pups that had propionic acid (PPA) induced autism showed a protective effect on neurotoxicity. (3) PPA significantly decreases glutathione transferase levels, making it more difficult to recycle glutathione. Vitamin D attenuated this, therefore increasing useable glutathione. This adds to it’s overall anti-inflammatory and detoxification effect. Another animal study (5) showed vitamin D had a significant effect on maternal immune activation during gestation. Low maternal iron, zinc deficiency, elevated oxidative stress, and pro-inflammatory cytokines all can impact fetal immune activation. Although cytokine levels did not change in the offspring, maternal administration of vitamin D in immune-activated mice showed decreased stereotypy and fear behaviour in offspring compared to controls.
The neurotransmitter serotonin is used in neuron signalling and also to ‘shape’ neuronal networks in the growing brain. Serotonin can promote social behaviour and interpret emotional cues. Levels are chronically low in autistic individuals during childhood. The anomaly is that high serotonin levels have been measured in the blood of some children with autism as well. Researchers hypothesize that vitamin D can both repress and activate the tryptophan hydroxylase enzyme which synthesizes serotonin. This is further supported by the inverse relationship with vitamin D and melatonin. There are hypothesis that this vitamin also affects oxytocin and vasopressin hormone synthesis and bioavailability as well. Both being associated with increased social behaviour, exploration, and lowered social anxiety. (4)
2). Khaled Saad, et al. Vitamin D status in autism spectrum disorders and the efficacy of vitamin D supplementation in autistic children. Nutritional Neuroscience. Volume 19, 2016 – Issue 8. Pages 346-351 http://dx.doi.org/10.1179/1476830515Y.0000000019
3). Alfawaz HA, Bhat RS, Al-Ayadhi L, El-Ansary AK. Protective and restorative potency of Vitamin D on persistent biochemical autistic features induced in propionic acid-intoxicated rat pups. BMC Complementary and Alternative Medicine. 2014;14:416. doi:10.1186/1472-6882-14-416.