The promise of supplements

I get lots of questions from patients with joint disease about nutritional supplements- the type of stuff available at Costco in a large bottle. None of the stuff in these pills has ever been proven to get to the joints- like many vitamins, it just goes out the GI tract. So the issue is, this is probably a waste of money. Even doctors have been taking the stuff- but of course they are people too, and everyone is looking for a free lunch. Remember St. Johns's Wort (for depression)? Someone- I think Osler- once said you have to use a new medicine real soon, before it loses its efficacy. There is a high "placebo effect", be aware of that.
As to safety, I also get concerned that chondroitin in supplements is not from cows that have been tested for mad cow disease- it is not regulated. That is why this material is not sold in a pharmacy etc. So caveat emptor!