Vitamin A, also known as retinol, is a fat soluble vitamin and is most bioavailable in the body. The water soluble form is called beta carotene and is less active, especially in those with thyroid disorders. Most literature on retinol deficiency focusses on conditions of the skin, mucous membranes, and eye/vision impacts. A review from Siegenthaler J, et al. (1) outline that retinoic acid from the arachnoid brain meningeal layer is one of the signals guiding glial, neuronal, and progenitor cell growth. Trans retinoic acid is a hormone derivative of vitamin A. It binds to retinoid receptors and retinoic acid receptors in the nucleus of the cell.
Possibly one of the more influential papers with respect to visual motor planning in autism is the research of Meg Megson, MD out of Richmond, Viriginia. (2) Many environmental toxins can uncouple G-alpha protein receptors from retinoid receptors in the brain. The natural cis form of vitamin A can reconnect the G-alpha receptors to retinoid pathways in the hippocampus. This improves vision, sensory perception, language processing, and attention in autism. Quite simply put, many autistic individuals don’t have the visual acuity to process where they are in space and the people they’re with. Natural cis forms of vitamin A are found in cod, salmon, and liver, which many people don’t consume in the modern diet.
There is also the relationship between oxytocin secretion from the placenta, vitamin A, and the developing fetus. Oxytocin is known to affect social interaction and behaviour in autistic individuals, and administration with intranasal oxytocin improved social features in autistic teenagers. CD38 is a glycoprotein that helps to release oxytocin in the brain, and levels are lower in mouse models of autism. Gamliel M, et al. showed that trans-retinoic acid can up regulate CD38 protein in tissues. Therefore vitamin A levels in pregnancy may be preventative in developing autistic characteristics of the child. The oxytocin-CD38-vitamin A axis influences the developing brain and needs to be further evaluated in utero. (3)
1). Siegenthaler JA, Ashique AM, Zarbalis K, et al. Retinoic acid from the meninges regulates cortical neuron generation. Cell. 2009;139(3):597-609. doi:10.1016/j.cell.2009.10.004.
2). Megson MN. Is autism a G-alpha protein defect reversible with natural vitamin A? Med Hypotheses. 2000 Jun;54(6):979-83.
3). Gamliel M, Anderson KL, Ebstein RP, Yirmiya N, Mankuta D. The oxytocin-CD38-vitamin A axis in pregnant women involves both hypothalamic and placental regulation. J Matern Fetal Neonatal Med. 2016;29(16):2685-90. doi 10.3109/14767058.2015.1101446.