I actually went through and I read all the articles and talks they've published and the details of the protocol. Yes, not all journals and articles and studies, etc. are created equal, but I like to know a position before accepting or rejecting it. I'm not really interested in ad hominems or anything dismissive along those lines, though I won't lie, I did have a laugh or two when reading the blog post...

Last night I also came across Mercola's piece, which though it makes some useful points, doesn't address the science behind the model Marshall advances. That's fine, he's not writing in a specialist journal.

A few thoughts:

1. Jumping from computer models to a clinical protocol is problematic in all sorts of obvious ways.

2. There are all sorts of other problems too, e.g., taking antibiotics long term is not prudent for a number of reasons that are apparent to anyone who knows about their side effects.

3. But I'm not really interested in the protocol, but the main claim underlying it all. The meat of the position/model is twofold: (a) vitamin D is an immunosuppressive akin to steroids, and (b) it works by suppressing VDR from functioning.

Firstly, underlying this model is the position that vitamin D deficiency is caused by disease not the other way around. Well, we know that this hasn't been settled. I could say much more here, but it just hasn't been settled either way by studies, so Marshall can't have this one. But for various reasons, my suspicion is that it is (perhaps at least sometimes) caused by disease but that's not based on hard science.

The reason this is important is that it allows Marshall to claim that autoimmunity causes VDR dysfunction and so immune system dysfunction (and it's this that leads to low D levels). Is there evidence for this? If anyone has read his work and his evidence for it, then I'd be curious to know what you think. If I'm not mistaken, the only evidence he has is computer simulation and then just some claims loosely based on some clinical examples, not actual studies, certainly not quality ones. But perhaps I'm wrong. Again, I'm not an expert on this stuff.

Now, let's take (a). This seems to be true and is supportive by all sorts of studies. Here are just two links:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406/
http://www.readcube.com/articles/10.12659%2FAJCR.894849

What does this all mean though? It's rather complex. What exactly is being suppressed? I'm not an expert so input is appreciated. I don't see enough evidence via Marshall's computer models of (b), namely, that VDR is being suppressed, and that's what's going on, but again perhaps I'm wrong. Kiwi, perhaps you have some thoughts here? It doesn't seem like we can know this.

So, is D suppressing the adaptive immune system in the sense that it's reducing inflammation (by working on the T and B cells), which a number of studies an articles claim, or that it's also reducing the immune systems ability to fight pathogens and to do its work basically? Or do we just not know enough about what or all that it's going? Obviously, key to all this is that it functions like a cortocosteroid. So what exactly does a steroid do to the immune system/mechanism of action, etc.?

I say this because there's also a personal dimension to all this, or personal experience. My levels were low. Then even a 1000 IU a day reduced my symptoms immensely. It very obviously reduced inflammation in my body. But is it also hindering my immune system from fighting off infections and doing whatever else it needs to do? Well, I don't have a baseline, but a few days ago I received my IgG numbers and they're low, not too low, but below normal range, so in the 600s. The rest of the immunoglobulins are fine, it seems. I don't have the IgG subclasses, but soon. I also have mild neutropenia, so I'm just below the normal range. Again, these are the only set of numbers that I have, but they're low. Is the D suppressing production of neutrophils and IgGs? Is this even possible? I just don't know enough about how it all works to say anything here.

Do I think that taking vitamin D or hormone D is suppressing my VDR function? I don't know. Theoretically it's possible, but I don't see the evidence or I don't find it convincing based on what I've read from Marshall and those who argue along the same lines. My guess is no, though it's not impossible, perhaps not even implausible. We know that supplementing hormones can have short term benefits, which I clearly have from D, but that long term is can lead to problems with respect to the body's own natural function.

But at this point I'm more interested in the more supported point, namely, that D is functioning as a corticosteroid. This is a common point, but the studies seem to stop at saying with certainty exactly what's going on. I could say and write more, but I'll leave it at that. I'm not sure if others are as interested in this as I am, but it's clearly a very important issue.