MMS is not a new substance ... it is sodium chlorite, which has been around for decades as a health supplement, with an excellent track record as far as adverse reactions go.
Jim Humble did add a couple of twists to the original protocol: pre-activation before ingestion using a weak acid, and increased strength.
As far as the oxygenation question: it has long been assumed that chlorine dioxide is oxygenating the body ... however, Jim Humble asserts that what it is really doing is acting as a cleanser. I think that I tend to agree with him at this point; that, rather than simply adding oxygen into the body, what chlorine dioxide is really doing is the same thing that chlorine dioxide does naturally within the body, boost the immune system and attack pathogens.