If even some of the damage done by vitamin D deficiency during fetal development is reversible, we'd expect to find that vitamin D supplementation would help reduce autistic symptoms at least to some extent. There aren't yet many good studies on this subject, but what we know is encouraging. A multivitamin supplementation study of 20 autistic children in 2004 showed improvements in sleep and gastrointestinal problems that are common in autism (that study only provided 150 units of vitamin D per day, which as we'll see is probably well below the minimum requirement).71 Similar multivitamin studies have shown improvements in cognitive function even in apparently normal schoolchildren, according to one review of 14 separate studies.
What's remarkable (and heartbreaking) is that while these studies show very little effect on most of the children evaluated, about 20% of the children had substantial gains in performance. This 20% might represent a vitamin D-deficient subgroup of children-a tremendous number if these figures hold nationwide.
We would also expect that consumption of vitamin D-rich foods by pregnant women would improve cognitive performance in their infants, and indeed Cannell provides evidence that high maternal consumption of fish, rich in vitamin D, is associated with better cognitive outcomes in infants. Another recent study demonstrated that infants born to mothers with very low seafood intake had higher risks for having low verbal IQs, less well-socialized behaviors, and poorer fine motor and communication skills. As Cannell persuasively argues, these deficiencies are "eerily similar to [those found in] autism."
A WORD ABOUT DOSING
To reach the 25-hydroxyvitamin D blood levels that Life Extension recommends for optimal health of 50-60 ng/mL, most typical Americans will need to use dietary supplements, given the real risks ofprolonged exposure to sunlight or UV tanning lights. But neither officially-recommended daily intakes of vitamin D (400 IU/day) nor consumption of vitaminD-fortified foods can effectively prevent vitamin D deficiency. As leading researcher Dr. John Cannell points out, "Adequate oral supplementation will require doses that might make a practitioner initially uncomfortable, as physiological doses of vitamin D, in the absence of sun exposure, probably range between 400 IU/day for premature infants to 10,000 IU/day for the morbidly obese." Cannell goes on to cite another expert, Dr. Robert P. Heaney of Nebraska's Creighton University, who estimates that 3,000 IU/day is required to assure that 97% of Americans obtain levels greater than 35 ng/mL. The Canadian Pediatric Society recommends that pregnant women should take 2,000 IU vitamin D daily to reduce the risk of autism and other adverse health conditions in their children.88 In a recent comprehensive review, Dr. Cannell recommends that "parents supplement breast-fed infants with at least 800 IU of vitamin D daily, while formula-fed infants need 400 IU per day. Toddlers and young children who do not get regular sun exposure should take 1,000-2,000 IU daily year round, depending on body weight, keeping in mind that current Food and Nutrition Board recommendations state doses up to 2,000 IU per day are safe for children over the age of one." Dr. Cannell and other experts believe that autistic children may require even higher blood levels of vitamin D than other individuals, and should take enough vitamin D to maintain serum 25-hydroxyvitamin D levels of approximately 70 ng/mL.
Exposure to UV Light-Another Clue?
We know that certain brain diseases such as multiple sclerosis are much more common in high latitudes where sunlight is scarce, and many scientists suspect that those conditions are directly related to chronic or seasonal vitamin D deficiencies. A strong positive association between latitude and the prevalence of autism has been reported for groups of children before 1985, which is what we'd expect if autism were related to vitamin D deficiency.3,4 Additional support comes from recent data from the Centers for Disease Control and Prevention (CDC), which found the highest prevalence of autism in New Jersey (the second most northern state in the survey), and the lowest in Alabama.
One might expect that babies born in late winter would have higher rates of autism if vitamin D deficiency were involved, since their mothers would have spent most of their pregnancies in fairly low-sunlight settings. While one report suggests that late winter birth dates are associated with higher rates of autism, the literature isn't consistent on this topic. Cannell argues that in fact this would be expected if the critical time for the deficiency to cause damage was not only during gestation, but also in early childhood, and indeed animal studies suggest just that. Lower rates of autism have been found in rural compared with urban areas, further supporting the idea that low sunlight exposure may be a contributor. And a fascinating study recently demonstrated that autism rates are substantially higher in geographic areas where precipitation is highest (the implication is that people in such areas spend less time outdoors, thereby reducing their vitamin D-producing sun exposure).
Finally, air pollution is now known to reduce UV light exposure sufficiently to lower vitamin D levels to the point at which experts are recommending supplementation, and one recent study demonstrated an association between air pollution and autism (of course this particular association could as easily be due to toxins in the air-demonstrating how much we still have to learn about this mysterious condition).
UV-Blocking Skin Pigment-Further Support for the Vitamin D Deficiency Theory
If fetal vitamin D deficiency is at the root of autism, we should expect to find higher rates of autism among children born to dark-skinned mothers, because melanin, the major skin pigment, is an extremely efficient blocker of UV light. As Dr. Cannell points out in his review, studies of this nature are difficult to perform and interpret, though there is limited evidence of higher incidence of autism in American black children. Two European studies published in 1995 also showed higher rates of autism among children of dark-skinned immigrants (up to 200-fold higher in one study). Since some studies suggest that darker-skinned individuals are more likely to be deficient in vitamin D than those with lighter skin tones, this provides another compelling reason for those with darker skin tones to diligently monitor their vitamin D status.
There seems to be little doubt that a significant proportion of the epidemic of autism is real, and not just a fluke of over-reporting and over-diagnosis by anxious parents and physicians. As many Life Extension reports have documented, there's equal certainty that we also face an epidemic of vitamin D deficiency as we steadily move away from old ways that exposed us to more vitamin-D producing sunlight. The theory that the two epidemics are inextricably linked is supported on myriad independent grounds, and as Dr. Cannell himself points out, is readily susceptible to rigorous testing. While we are awaiting those results, however, it seems prudent to maximize vitamin D status in pregnant women, infants, and young children and infants, aiming for levels found in humans living in a sun-rich environment, between 50-60 ng/mL (blood testing for 25-hydroxyvitamin is recommended as the only way to make the diagnosis and to assure treatment is adequate and safe). One recent study noted, "Supplemental doses of vitamin D and sensible sun exposure could prevent deficiency in most of the general population." Under the leadership of brilliant scientists like Dr. John Cannell, we may be privileged to witness at least the beginning of the end of the scourge of autism among our children.
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Have a blessed day folks!