In recent years we have been told to avoid the sun. Anyone reading women's magazines, in fact, will have been advised to put on sunscreen on face and hands "just in case" as those few moments walking from the car to the workplace
or grocery store might be enough to cause aging
and cancer cells to go nuts in our vulnerable skin.
We slather on sunscreen and sunblock, which for the most part completely blocks the UVB sun rays that increase our cancer protective vitamin D and allows in some cancer causing UVA - to me that sounds like a silly thing to do!
Why not get enough sun to get a little color, obtain a healthy amount of the essential vitamin D and then cover up to avoid sunburn and further problems? It is certainly what our ancestors, absent suncreen, must have done for hundreds of thousands of years.
Vitamin D is minimal in the diet (fortified dairy products and cod liver oil provide a small amount), and we have historically obtained 90% or so of our vitamin D through our skin. In fact, someone with fair skin in the midday hours of the summertime can make up to 12,000 IU vitamin D within 20 minutes or so with arms and legs exposed. A more typical amount in someone with an adequate blood level of vitamin D would be 4,000 IU - a cup of milk has 300 IU. So you can see you have to drink an awful lot of milk to make up for sun avoidance.
In recent decades, near-complete sun-avoidance is what we've been told to do (particularly in the midday, which is when we make the most vitamin D.) Health-conscious folks blocked those dangerous rays from our vulnerable hides and definitely protected the soft skin of our most precious children. But could that increased vigilance have a terrible cost? Could a lack of sunshine and suboptimal amounts of vitamin D be a possible cause of autism spectrum disease in our children?
Vitamin D researcher Dr. John Cannell has spent a great deal of time covering this topic, so I don't need to reinvent the wheel here. I'll note the highlights and link his articles for the full discussion. He began with an article in 2007, followed by a comprehensive update in 2010. (My thanks to fellow blogger Jamie Scott for pointing me to these articles originally.)
Cannell's 2007 article
Update, August 2010
Dr. Cannell's major points (he has several more, but I'll note the more compelling ones):
1) Autism is increasing, as is vitamin D deficiency, and the autism epidemic came upon us at the same time the major health authorities advised us to eschew the sun.
2) Vitamin D is likely central to brain development as a key helper in neural development and neuroprotection. In addition, autism is likely mediated by inflammation, and vitamin D is a key player in anti-inflammatory processes. Also, vitamin D enables glutathione, the "master antioxidant," clear our system of free radicals, and glutathione also acts as a chelating agent to bind toxic heavy metals such as mercury, which kids with autism have a tough time clearing from their systems.
3) Williams syndrome, a chromosomal disease which (among other things) results in abnormally high levels of circulating active vitamin D in early childhood, results in kids who are especially social and overfriendly - rather the opposite of autism symptoms.
4) During pregnancy, boys' brains are bathed in testosterone, and girls' brains in estrogen. Estrogen is known to have many vitamin D enhancing properties. This could account for the 4:1 ratio of boys to girls suffering from autism.
5) Studies show autism births occur most often in March, at the end of winter, when vitamin D levels would be lowest.
6) African Americans seem to suffer from a higher rate of autism, and they also have a higher rate of vitamin D deficiency than people with lighter skin. In Europe, the children of darker-skinned immigrants have higher rates of autism also.
7) Rickets, due to vitamin D deficiency, is characterized by hypotonia (poor muscle tone) and developmental delay, as is autism.
8) Autism seems to be higher among the kids of highly educated women, and they are more likely to follow guidelines for sun restriction for themselves and their children.
All told, it makes for a compelling theory, and Dr. Cannell has a point in that "this theory deserves immediate attempts to disprove it." My only major issues with it are that rickets is not autism, and that there may not be a new autism epidemic after all, but we are only now recognizing how prevalent the disorder actually has been all this time. But I could certainly be wrong about that second bit. And, by all means, let's please give pregnant women guidelines for sufficient vitamin D and get the kids to play outside! And let's study vitamin D and autism directly.
Dr. Cannell touches on this next part in his 2010 article - we have a lot to learn from history. If vitamin D deficiency is the cause of autism, then all of this has happened before. Rickets, characterized mostly by bone growth abnormalities in children, became endemic during the industrial revolution, when people in cities, especially, seemed to spend very little time outdoors, diets were poor, and many children died, as there was no cure. Eventually, cod liver oil and sunbathing were shown to prevent and improve the disease.
Here is Dr. Cannell's quote: "If adequate amounts of vitamin D prevent autism, one would expect children with rickets to have an increased risk of autism. To my knowledge, the neuropsychiatric symptoms of rickets have not been studied in the modern era. However, at least two old papers have addressed it, both published before Kanner described autism in 1943. Both papers describe ‘weak mindedness,'‘feeble minds,'‘mental dullness,' unresponsiveness and developmental delays. Even more intriguing, both papers report that the mental condition in rickets improved with vitamin D."
In Nutrition and Physical Degeneration, first published in 1939, a writer named Laird had the following to say about the state of mental health at the time - keeping in mind this was published without a thought for political correctness, and certainly researchers or bloggers would phrase some things quite differently these days! (1):
The country's average level of general ability sinks lower with each generation. Should the ballot be restricted to citizens able to take care of themselves? One out of four cannot. . . . The tail is now wagging Washington, and Wall St. and LaSalle Street. . . . Each generation has seen some lowering of the American average level of general ability.
Although we might cite any one of nearly two dozen states, we will first mention Vermont by name because that is the place studied by the late Dr. Pearce Bailey. "It would be," he wrote, "safe to assume that there are at least 30 defectives per 1000 in Vermont of the eight-year-old mentality type, and 300 per 1000 of backward or retarded persons, persons of distinctly inferior intelligence. In other words, nearly one-third of the whole population of that state is of a type to require some supervision.
Dr. Weston Price summarized the thinking about medicine and disease at the time thusly:
The problem of lowered mentality and its place in our modern conception of bodily diseases has not been placed on a physical basis as have the better understood degenerative processes, with their direct relationship to a diseased organ, but has generally been assigned to a realm entirely outside the domain of disease or injury of a special organ or tissue. Edward Lee Thorndike, of Columbia University, says that "thinking is as biological as digestion." This implies that a disturbance in the capacity to think is directly related to a defect in the brain.
Of course back then they did not have the diagnostic categories or laboratory tests to differentiate between the varieties of autism, mental retardation (most commonly due to hypothyroidism), and cerebral palsy. But even Dr. Price complained that medicine was becoming too specialized, without an holistic view. And it is nice to see him recognize that mental illness is biologic, way back in the early part of the century. Pretty good considering that psychiatry is something of the red-headed stepchild of modern medicine even today.
It does make you wonder. This "mental degeneration" of that time period, in part, led to the rise of eugenics, and even Nazis. In the late 1800s, admissions to mental asylums skyrocketed. The mental health of the western world seemed to improve after World War II, when bread began to be fortified with B vitamins, and people recognized the importance of at least a small amount of vitamin D. But anxiety, depression, and "bodily degeneration" is on the rise again with our change to industrial processed food, and perhaps this change in nutrition and increase in sun avoidance has contributed to an increase in autism spectrum disorders as well.
In historical novels, a curative practice for what ails you is always to take some time visiting on the seashore. One would expect to get more sun then, and eat more nutrient-rich seafood, and be bathed in the magnesium-rich waters of the ocean. Sounds like an excellent curative course to me!
Don't get burned, but don't hate the sun - those midday rays (in moderation) are the best source of a healthy amount of vitamin D. Skin cancer is usually easy to catch early and have removed, whereas higher levels of vitamin D have been shown to be protective against may different kinds of much more common cancers that are generally more difficult to catch early - including colon, breast, and prostate cancer. Melanoma is the deadly exception to the relatively easily managed and removed rule of skin cancer - but melanoma often occurs in areas not exposed to the sun, and its incidence seems to be increasing the more we use sunblock. And, of course, melanoma is much rarer than colon or breast or prostate cancer.
The full impact of lack of sunshine on mental health in general is unknown, but I do suspect there is a connection. In the future I will publish articles about links between depression and schizophrenia and vitamin D levels. One final plug for sunshine, not just vitamin D supplementation - according to Dr. Michael Holick in The Vitamin D Solution, we make 5-10 additional photoproducts in our skin. It seems prudent to think that if our skin is spending time and energy making something, it will likely be a molecule we need. While these issues are not fully understood, I like to fall back to evolution as a sensible guide. Our species has exposed a lot of skin to the sun. We need to fully comprehend the risks and benefits (for total health, not just skin cancer) of hiding from it before we make general recommendations to never let skin go exposed.
Other articles like this one at Evolutionary Psychiatry
Copyright Emily Deans MD