Thanks for posting. You make some good points. I agree that taking a look at the vitamin D levels of unsupplemented populations or populations in rural/non-cosmopolitan areas would be interesting. The problem is that there are only a small handful of studies. It’s actually quite difficult to find data on unsupplemented populations considering that all the milk that Europe ships to third world countries has been supplemented for decades.

Dr. Marshall and I were actually trying to look for studies on the levels of vitamin D of Chinese people. We ended up with only one study on Chinese infants which showed that they were born with 25-D levels between 5-14 ng/ml, and none developed rickets. Obviously, more studies would be helpful. We will be testing the 25-D and 1,25-D levels of subjects in our trial at West China Hospital and the results should be of interest.

This Knowledge Base section describes this small group of studies:
http://mpkb.org/doku.php/home:pathogenesis:vitamind#populations_that_avoid_vitamin_d_remain_healthy_despite_low_levels_of_25-d

The acceptable range for 25-D has shifted as researchers have found increasing correlations between high 25-D levels and absence of disease, yet this relationship does not imply causality as you know. In the next day or so, Paul and I are going to post an article that I think will address some of your questions in this area. The article describes our experience at the 2009 IOM conference where a panel of researchers is currently deciding whether to raise the DRI of vitamin D, so check back in a couple days.

Take care.

Best,
Amy

I understand that there was a similar study of Chilean citizens living at high altitude who also consume diets without 25D enhancement. Have you seen or heard of it? Any further comment?

I am also aware of 25D level measurements obtained in military recruits that date back for decades. The data were collected and retained by the US Military. The trend reportedly shows falling 25D levels since data were first collected and are interpreted to mean that the US young male military recruits need more supplementation by some. Are you aware of these data?

I am understanding you to imply that the D levels we have always considered “normal” are, in fact, skewed upwards due to factors such as prexisting occult or subclinical disease, unrecognised dysregulation of normal 25D/1,25D metabolism, supplementation and cultural changes favoring well tanned skin. In light of the more complete understanding of the role of 25D and 1,25D in metabolism, particularly the immunomodulatory properties of these to secosteroidal hormones, an in depth review of extant data on D levels amongst differing populations and cultures would be timely in helping the public understand what are truly normal D levels. It might also stimulate more introspection on the part of the medical scientists who argue that we are suffering from a worldwide “vitamin” D deficiency.
Comparing the D levels of Aborigines in Australia with the cohabiting caucasian population of European descent might be instructive as would a comparison of rural and metropolitan Chinese populations.

Finally, it would be interesting to look at the history of the collection of D levels that became the basis for the “normal” levels. Were “normal” levels revised with changing assay techniques? One could wonder if these so called “normal” levels were properly established at the outset and if they were ever revised by the FDA or other regulatory body.

I wonder how many miscellaneous symptoms are reported by patients who are considered healthy might be attributed to the syndrome of “Hypervitaminosis D” because our “vitamin D” ruler is improperly calibrated.

There arn’t too many variables. In order to better understand vitamin D metabolism it would be helpful to take a better look at Figure 1 in Dr. Marshall’s latest BioEssay. The figure shows how all the various forms of vitamin D are controlled. They are very tightly regulated. So if the body is left alone, it can naturally keep the vitamin D metabolites in a healthy range.

The correct levels of vitamin D are those which would result if the population starts to eat a natural diet once again (no more fortified foods!) and gets only moderate amounts of sunlight. Those people who desire to have their vitamin D metabolites in the healthiest range must also make the effort to eliminate the Th1 pathogens that cause chronic inflammatory disease. That’s because the bacteria themselves also dysregulate the VDR and subsequently vitamin D levels.

So, to review, in order to have vitamin D levels in a normal range you must first kill the pathogens that dysregulate vitamin D metabolism. Then, if you eat only the vitamin D nature intended us to consume and stay out of excessive sun, the body itself should be able to keep your levels in a range that will maintain your optimal health. No worries at that point, as your body has naturally set the levels that will keep you in the best shape.

Best,

Amy

If we really don’t know what D levels should be at because of supplementation, etc… How do we know what is TOO high and what is TOO low?

This is very confusing… How will we ever know what the D levels should be at???

My 25D was 15 and 1,25D was 29.. How do I know that isn’t normal for me??

I just think there are too many variables….

Good article as usual!

I probably should have discusses 1,25-D more in the piece, but the researchers are incredibly vague about the patient’s 1,25-D levels.

The state that the subjects’ levels of 1,25-D were in a normal range, yet later on they say that the 1,25-D levels were in a normal range for people getting sun exposure which, in my opinion, would have allowed them to classify high levels as “normal.”

Never in the paper can I find a place where they actually define the 1,25-D range. It doesn’t help that on my computer the full text of the paper opens in a wide screen format that makes the article difficult to read. Still, I don’t think I missed anything. I see a graph of 1,25-D levels relative to sun exposure, but I can’t really extrapolate data from the graph. Then I see no information comparing 25-D levels to specific 1,25-D levels.

So in being so vague about the subjects’ 1,25-D levels it’s almost as if they didn’t bother to test them at all. When I say this research team leapt to a conclusion of vitamin D deficiency without taking other factors into consideration I mean it. It’s almost as if when they found the low 25-D levels nothing else needed discussion, including 1,25-D levels. And since the medical community is so used to hearing about “deficiency” I don’t think anyone has really questioned the rest of the information presented in the study.

As Dr. Marshall has made clear, were never going to get the full picture on vitamin D until researchers take 1,25-D levels just as seriously as 25-D levels, something which this team very much failed to do.

Here’s the link to the full article in case you want to try to figure out more about the subjects 1,25-D levels on you own:

http://mail.google.com/mail/#inbox/11ab0dd4c8ffdfda

Best,

Amy

Duh!!! Like probably inversly related?

Phil

You state that the team measured both metabolites of D. What were the 1,25D levels?

I was expecting one of your alternate explanations to be that 25D was low because it was converted to 1,25D in the Th1 sufferers.

Can we establish that these folks have not had a diet of D supplements?

Phil