If he runs around in the sun all day without a shirt he probably won't be vitamin D deficient as the body can synthesize vitamin D in the skin. For many of us in Northern climates who work indoors during the short days of winter, especially susceptible persons of N. European ancestry, Vitamin D can indeed become low and may require supplementation. Seasonal affective disorder and other disorders are linked to low Vitamin D levels.

Also, the FDA guidance of 400 IU per day is barely enough to ward off rickets and is considered outdated even by many traditional practitioners. A Harvard study shows that toxicity is generally not a concern for dosages of 10,000 IU or less per day, which is about what the skin can generate when exposed to ample sunlight.

I think he's on to something. So is this guy ------> http://suppversity.blogspot.com/2012/11/health-exercise-quickie-vitamin-d.html http://suppversity.blogspot.com/2011/10/vitamin-d3-fat-synthesizer-rodent-study.html http://suppversity.blogspot.com/2012/09/stronger-leaner-or-fatter-less-muscular.html http://suppversity.blogspot.com/2012/05/hypothesis-does-vitamin-d-deficiency.html http://suppversity.blogspot.com/2012/10/low-vitamin-d-insulin-resistance.html

I think that mega dosing Vitamin D is immmuno suppresive, so can beneft those with autoimmune issues. Many in the Paleosphere have autoimmune issues so perhaps that is where the megadosing comes from?

This is an interesting idea, thanks for sharing this article.

I do think he's on to something. I've seen some of this evidence before and while it's a bit preliminary, I think vitamin D supplementation could carry risks if you have impaired conversion of the supplementary form to the active form of vitamin D.

This conversion ability probably varies depending on the person, but one of the main factors affecting this is magnesium deficiency, which runs rampant in countries like the U.S.

This may be yet another example of the fact that no nutrient works in a vacuum. There are frequently risks incurred from massive supplementation of otherwise highly beneficial nutrients without regard for the other nutrients which play an important role in its regulation. For example, Chris Materjohn has written a lot about the interplay between vitamins A, D, and K(2) and how they help mitigate the toxicity of each other.

We're dealing with a lot of speculation, but I'm hedging my bet on even fairly large doses of vitamin D posing very little danger to a person replete in vitamin A, vitamin K(2), and magnesium. This is obviously a niche highly unlikely to be represented in your average vitamin D supplement study drawing from the population at large, but more likely among the paleo and WAPF eaters.

And I still think there's lots of research supporting vitamin D levels as a casual factor in reducing disease risk, although the idea that D might be low as a consequence rather than a cause of disease is an interesting one that may be true in some cases.

I take 6,000 Ius of D3 to keep my asthma at bay. I need to keep my blood level at about 80 ng/ml to avoid any symptoms.

So far, so good. The only time my asthma symptoms have come back in the last 3 years was when I did an experiment & relied on sun exposure only for 3 months.

I live in Santa Fe, NM and got an hour in a bikini a day between 11 am and 1 pm. Not so great for the skin, but I am Type IV complexion on the Fitzpatrick scale and need that amount of exposure to get enough sun.

I tested after those 3 months and was at 57 ng/ml--definitely in the "optimal" physiologic range, but not sufficient to deal with the inflammation that causes my asthma.

So I think the choice to use supplements may depend on any health conditions you may have and on how much sun exposure you are willing/able to get.

I take between 20-30,000 iu's every 7-10 days. I don't supplement in-between. I've been doing this for about 8 months. My latest levels were around 65. Before I started, they were in the high 30's. Obviously anecdotal, but it HAS shown some benefit by supplementing this way. I much prefer this one dose instead of a few thousand iu's each day. I take way too many other supplements and micromanage many other things to worry about it when one huge dose can work just as well.

I live up north and it takes 5000 IU just to have normal levels. Even if I ran around with my shirt off I still wouldn't make enough to store what's needed for the winter.

Mommypotamus has a great article on this subject. It completely changed my view on vitamin D. I still take some but I really don't rely on it for keeping myself healthy. Gotta have daily exposure, even in the winter and really focus on getting those stores up during the spring and summer. The vitamin D manufactured in your skin is a totally different animal. Not to mention there are so many different kinds of vitamin D and probably other nutrients and compounds we haven't even discovered yet from sunshine exposure. You just can't replace a healthy lifestyle with a pill. It'll always catch up with you. http://www.mommypotamus.com/why-vitamin-d-supplements-cant-replace-sunshine/