One of the things that came up in regard to that last post was the idea about blood being acidic or alkaline. I don't think that most people outside the medical sciences realize how much effort the human body expends on these matters. Those of us who keep up with these topics could do some good by letting people know how robust this stuff is.
To listen to most quack nutritionists, your body is in perpetual danger of flying apart. This thing is out of balance, that thing over there is running low, all these other things are set totally wrong. You need. . .herbal supplements! Of the kind that I happen to sell! Fix you right up! Of course, if you stop taking them, your physiology might well just start wobbling around again, so you'd better play it safe. . .and it so happens that we offer discounts on a yearly supply. . .
Now, it's not like things can never get out of whack, but a lot of metabolic energy goes into keeping that from happening. Biologists, MDs, and medicinal chemists are always getting surprised at just what sorts of abuse a living system is capable of absorbing without breaking down. Homeostasis is what I'm talking about. That concept applies to a huge number of living processes, but we'll stick with one dear to Kevin Trudeau's alleged heart: acidity and alkalinity.
The pH of the blood is held steady around pH 7.4 by several systems, not all of them well characterized, but all acting at the same time. The amount of carbon dioxide that the lungs exhale (or retain), the actions of the kidneys, and the circulating blood proteins are all involved. (Buy why it's pH 7.4 and not some other value is one of those very good questions that no one has a very good answer for.)
One of the main places that your body can go acidic is in muscle tissue during exercise. That's due largely to the buildup of lactic acid from anaerobic metabolism, and can send the interstitial fluid between muscle cells down to pH 7, much lower than blood gets under the same conditions. (There seems to be something about the capillary wall that excludes the excess acid, which is yet another control mechanism.)
Going alkaline is usually a sign that something's off with your breathing or with your kidneys. (You'd better hope that it's the former, because you can stop hyperventilating a lot easier than you can stop kidney trouble.) In either case, it takes a lot to overload the various pH controls, and if you do manage to - in either direction - you can be headed for serious trouble and even death.
This should illustrate why the "alkalinity causes cancer" theories from the likes of Kevin Trudeau are nonsense. The blood of people who get cancer is at pH 7.4, like everyone else, and that number (if it fluctuates at all) moves around according to whether or not that person just took the stairs, rather than whether they're drinking "coral calcium water" or whatever damn thing. pH changes in your stomach aren't reflected in the blood - if they were, we'd be dead as soon as we smelled lunch.
But all you have to do is Google any combination of "blood" "acid" and/or "alkaline", and you'll step off into a swamp of people who are trying to convince you otherwise. It's a simple, appealing theory, which if it were true it would explain a lot and immediately suggest ideas for treatment. But it's wrong, and it's been known to be wrong for a very long time. The only utility it has is as a prybar to separate people from their money.