Anyone with the medical knowledge to evaluate an extraordinary claim?

I don't know why this post is being downvoted, but in any case I have a better idea: use it as a rationality exercise to figure out whether he is a crackpot without acquiring any additional biological/medical knowledge or consulting any biological/medical experts. I bet you can convince yourself to a near-certainty (my feeling is something like a 10^-7 chance of being wrong) that he is a crackpot using only information already available to you and some good heuristics.

Of course you may wish to consult John Baez's Crackpot Index, which is funny and insightful. But the best heuristics I can suggest are the three points of Sean Carroll's Alternative Science Respectability Checklist:

1. Acquire basic competency in whatever field of science your discovery belongs to.
2. Understand, and make a good-faith effort to confront, the fundamental objections to your claims within established science.
3. Present your discovery in a way that is complete, transparent, and unambiguous.

See also Scott Aaronson's extremely good Ten Signs a Claimed Mathematical Breakthrough is Wrong, which makes the point that you can usually confer crackpot status on the basis of superficial characteristics alone, and his Eight Signs A Claimed P≠NP Proof Is Wrong, which is some sense a specific instantiation of Carroll's three points (especially the first two).

From these kinds of heuristics and some simple observations, the guy is too obviously a crackpot to even be worth asking an expert about.

I'll point out just a couple of things:

• On a superficial level (which often provides great Bayesian evidence!), the guy can barely type -- his posts are littered with weird typos, spelling mistakes, grammatical mistakes, and incoherent sentences.
• He gives no account of why medical science has failed to figure out this stuff.
• He emphasizes how exceptionally simple all his discoveries are, that biology boils down to just a few fundamental principles -- that the same basic idea will "cure" literally all common diseases. Again, just think of how much seemingly settled biological science would have to be wrong for that to be possible.

I chuckled when I saw this: Another of the forum members mentioned "the thing you were working on a few months ago" and LetterRip's response included:

Also the theory I had back then was quite wrong. This one isn't.

Going off this post of his, it sounds like people who take a daily multivitamin should have dramatically lower morbidity for at least some diseases that aren't already typically associated with nutrient deficiency. Studies on that subject already exist, and I can predict what they'll have to say, though I can't look for them right now.

Hundreds of thousands of Americans die of medical malpractice every year. Anyone who holds medical science in such high regard that they can do-no-wrong has not studied its history. American medical practice especially, compared to European standards, is positively wretched to the average patient.

I would not assume that this man's breakthrough is real, but it is ludicrous to assume its falsity without any expertise to make such a judgement. Moreover, if his methods are reasonable and his results happen to be incorrect, it does NOT make him a "crackpot". Seriously, a scientist being wrong should be considered the norm: scietists are almost NEVER fully correct in their assertions. To call a scientist a "crackpot" is akin to calling a politician a "fascist": sure, there are a few milling about, but overwhelmingly it's just a cheap insult. Shame on yea who consider yourselves rationalists but use such emotionally-charged, biased terminology and make epistemology claims they have no qualifications to make.

...Additionally, there are the institutional criticisms to make of modern scientific practice. Of course, some "scientific" institutions are horribly corrupt, but even those which are run legitimately can fall victim to cognitive, publication, and funding biases. http://www.ted.com/talks/ben_goldacre_what_doctors_don_t_know_about_the_drugs_they_prescribe.html (There's plenty more to look up. Privately-funded studies far more likely to net positive results; positive results are far more likely to be published; negative results are more likely to be redacted after publication...)

I didn't read through everything but if I understand this theory correctly it has a huge flaw:

Evolution would have countered it.

The proposed causes for diseases would be very easy for evolution to "cure". Therefore these diseases wouldn't exist if the theory was correct.