As evidence of widespread vitamin D deficiency grows, some scientists are wondering whether the sunshine vitamin--once only considered important in bone health--may actually play a role in one of neurology's most vexing conditions: autism.
The idea, although not yet tested or widely held, comes out of preliminary studies in Sweden and Minnesota. Last summer, Swedish researchers published a study in Developmental Medicine and Child Neurology that found the prevalence of autism and related disorders was three to four times higher among Somali immigrants than non-Somalis in Stockholm. The study reviewed the records of 2,437 children, born between 1988 and 1998 in Stockholm, in response to parents and teachers who had raised concerns about whether children with a Somali background were overrepresented in the total group of children with autism.
In Sweden, the 15,000-strong Somali community calls autism "the Swedish disease," says Elisabeth Fernell, a researcher at the Karolinska Institute in Stockholm and a co-author of the study.
In Minnesota, where there are an estimated 60,000 Somali immigrants, the situation was quite similar: There, health officials noted reports of autism among Somali refugees, who began arriving in 1993, comparable to those found in Sweden....
I started to get interested in Vitamin D a few years back for personal and intellectual reasons. I had deficiency myself despite the fact that I tried to make a proactive effort to get a lot of sun exposure (I take 2,000 IU caplets and I'm fine now). Over the past year and a half I can attest that my respiratory health has improved a great deal. In any case, I was also trying to figure out a reason that relatively light skin seems to have evolved recently simultaneously across Eurasia. The model I thought might be plausible was that a switch to agriculture resulted in less Vitamin D in the diet, and dense living increases the power of disease. As it happens the past few years have seen a massive boom in medical research on Vitamin D. I've talked to people about this and can't help but express some skepticism as to whether there's some faddishness to this, and whether Vitamin D is a corollary as opposed to a causal factor in terms of health. Additionally supplementation is a big business. In any case, a lot to chew on. Finally, I also wonder if the role of novel infection might be at work among the Somalis. Perhaps predisposition to autism occurs due to a pathogen which Somalis have not been exposed to until this generation because of relocation.
There is certainly a fad at least in news coverage concerning Vitamin D.
But even if there is a fad the combination of skin color, less sun, less outdoorsy life and somali women adopting islamic clothing in Scandinavia means there is probably a need for extra intake of Vitamin D. Hell, I'm white, spend time outdoors and have to take Vitamin D during the winter months or I feel like a zombie.
Here's a swedish news item on the subject with an additional concern: Cultural sensitivity:
Razib, if there is a vitamin D-autism link then it could be via the immune system. A recent report out of Johns Hopkins finds evidence that the maternal immune system might be messing up the developing fetal brain and causing autism.
Finally, I also wonder if the role of novel infection might be at work among the Somalis.
Sorry if I'm slow, but it seems worth spelling out that this is compatible with the vitamin D hypothesis, since D is relevant to the immune system.
pun, The way I see it vitamin D was ignored for a long time because it wasn't seen as an antioxidant and the rage was to try to reduce cancer incidence. So vitamin D was ignored enough though it has far stronger prospects for reducing cancer incidence than the antioxidants do.
The "fad" really represents a long needed readjustment of priorities.
Here's a group dedicated to publicizing Vitamin D research:
They have a series of pages on autism.
One man's fad is another man's paradigm shift.
Randall preceded me - there's no conflict between Vit. D deficiency and the pathogen theory.
Here is an interesting lecture by a gentleman who studies Vitamin D. His main prescription is mainly sunlight, but he also explains how latitude and skin color affect production.:
I read about the proposed Vitamin D link to Autism in Scientific American.
I also got this from Dr. Gabe Mirkin's weekly newsletter (not yet online)
"Two recent studies show that vitamin D deficiency is far more common in people as they age (Journal of Clinical Endocrinology and Metabolism. April 2009)."
Dr. Mirkin is at: www.drmirkin.com
Can a contributing factor to rising autism rates be the rising age of mothers when they give birth?
A potential Vitamin D link also raises another question. Is it the Vitamin D deficiency in the mothers when they are pregnant that is the culprit, or lack of Vitamin D in the children as they grow and develop?
I just realized that the link at the beginning of your post leads to the Scientific American article I cited. Apologies.