I have often thought that the containers don't say what the contents will do because they don't do anything at all.
A lot of the people who make wild claims about the powers of supplements probably buy them in the firm belief that what they read in a mag, or whatever, about the product is true and so will feel a full and powerful placebo effect that they think is a true physical effect. I suppose that doesn't make the effect any less real, unless one is a 'non-believer' who won't get any such effect - if you get my drift!!