Vitamin D supplementation - a dilemma

The most frustrating thing about researching ME treatments via the internet is the total lack of consensus.  You may be able to deduce certain basic "truths"--remedies helpful to a mere plurality of patients--but it takes an enormous time investment to separate these tidbits from the rest.  Some PWME's believe this lack of consensus is because we all have different etiologies--different origins of our ME.  The theory goes: ME is a multi-system dysfunction, and some people need to prioritize certain functions over others.  Other PWME's believe we're still talking about 2 or 3 or more distinct illnesses.

Here's an example of the problem:  Vitamin D.  Many PWME's supplement vitamin D or eat foods rich in Vitamin D and increase sun exposure.  I myself am supplementing 10,000 IU's a day to get my  levels up into the 60's and 70's.  Vitamin D was cited by my doctor as one of the most important factors to boosting the immune system.

But there's at least one researcher , Trevor Marshall, who believes that Vitamin D supplementation is harmful.  Vitamin D is, technically, a steroid.  Marshall believes that, as a steroid, vitamin D actually suppresses the immune system.  I would love to be able to dismiss this theory as quackery, but the seed of doubt has already been planted.  At least one part of Marshall's article seems to have direct applicability to me:

"Epstein Barr virus – In a 2010 study of pregnancy-associated breast cancer, higher levels of 25-D were positively correlated with serum antibodies to Epstein Barr Virus, suggesting that EBV is able to better proliferate in patients who take vitamin D"

Honestly, after reading that article, I don't know what to do.  As a lay person with no medical background, I simply don't have the tools to separate fact from fiction.  Maybe no one does.  This might be one of those medical issues that requires further research before anything can be conclusively resolved.  So, as of right now, I'm almost inclined to stop taking the D3 until I get further clarification.

It's hard enough sticking to a supplement routine when you're 100% convinced that it is will be helpful, or at the very least, not harmful.  With this kind of doubt introduced....it makes me question my entire regimen.  What else could be potentially harmful?   While I think I've felt slightly better in recent weeks, it is impossible to pinpoint the reason.  It could be any one of the 10 or so supplements I take.  Or none at all.

For now, I simply have to bookmark it as one more thing to research later.

Update:  I found this thread discussing the Marshall theory of Vitamin D.  After reading it, I find myself more convinced by the arguments and links provided by Ted Hutchinson than I am by Marshall.  But, still, that nagging doubt will always be there in the back of my mind....