Sunlight and ShadowsOn
Research by the legendary Bruce Ames has thrown up new links between maternal vitamin D, or the lack of it, and autism (Patrick & Ames ’15). Their work indicates that adequate levels of vitamin D may be required to produce neurotransmitters dopamine, oxytocin, vasopressin and especially serotonin in the brain, where they shape the structure and wiring of the central nervous system and affect social behaviour.
This could explain why autism, which has been previously linked to low levels of serotonin in the brain and to low vitamin D levels (Grant & Soles ’09, Yang et al ‘14), has increased so markedly in the last three decades, in the wake of well-meaning but misguided government recommendations to minimize exposure to sunlight. It could also help to explain the staggering increase in depressive illness, as depression is also linked to low D status (ie Penckofer et al ‘10); and why sunbathing makes us feel good, although the beta-endorphins formed when sunlight hits the skin also contribute. It may also explain why we are constructed in such a way that we find sunbathing pleasurable; the feel-good factor encourages us to expose our skin to sunlight, protecting us from the many diseases linked to low D status.
I describe the government guidelines as misguided because in my view they suffer from gross sampling error. While today’s malnourished citizens may well be at increased risk of skin cancer after sun exposure, folks who are better nourished in terms of UV-protective phytonutrients are able to cope with sunlight much more easily (ie Stahl & Siess ‘12). This is why in the 19th Century, agricultural labourers who worked long hours outdoors were relatively immune to skin cancer.
I should point out that although low maternal vitamin D status is linked to increased risk of autism, other scientists have found that is not associated with ADHD (Strom et al ’14). Caution; this paper describes mothers in Denmark, where population D levels are very low and vitamin D supplements are disliked!
Grant WB, Soles CM. Epidemiologic evidence supporting the role of maternal vitamin D deficiency as a risk factor for the development of infantile autism. Dermatoendocrinol. 2009 Jul;1(4):223-8.
Patrick RP, Ames BN. Vitamin D hormone regulates serotonin synthesis. Part 1: relevance for autism FASEB J. 2014 Jun;28(6):2398-413.
Penckofer S, Kouba J, Byrn M, Estwing Ferrans C. Vitamin D and depression: where is all the sunshine? Issues Ment Health Nurs. 2010 Jun;31(6):385-93.
Stahl W, Sies H. Photoprotection by dietary carotenoids: concept, mechanisms, evidence and future development. Mol Nutr Food Res. 2012 Feb;56(2):287-95.
Strøm M, Halldorsson TI, Hansen S, Granström C, Maslova E, Petersen SB, Cohen AS, Olsen SF. Vitamin D measured in maternal serum and offspring neurodevelopmental outcomes: a prospective study with long-term follow-up. Ann Nutr Metab. 2014;64(3-4):254-61.
Yang CJ, Tan HP, Du YJ. The developmental disruptions of serotonin signaling may be involved in autism during early brain development. Neuroscience. 2014 May 16;267:1-10.