LindaA....True testimony....
10 years ago my husband's knee was shot. early 40's and looking toward a knee replacement within a few years.
I went to our local health food store and asked about shark cartilage. She says, that may work but I'd like to have you try this new stuff GS500.(Glucosomine) I asked about it and took some literature home, as well as a bottle of the stuff(120 capsules were $80.00 at the time)
It was a lot of money but my husband could hardly stand to walk, let alone ride dirtbike, ski or any of the other things he loves to do.
I never told him what it was, just slipped into his vitamins he was taking. (I wanted to see if it worked or if it was a placebo effect)
3 months later I noticed he wasn't limping anymore
6 months later I asked him how his knee was and let him in on the 'vitamin' I'd been giving him.
1 year later his knee was nearly 100%
This doesn't have the condroitin in it and after the mass marketing of Glucosomine products the price dropped dramatically (now$30.00/bottle)
A few times he ran out and he noticed an aching in his knee after a week without it.
Now he lets me know when his bottle is getting low.
Brands.......After Glucosomine became available in different brands, I tried a few, some maintained the healthy feeling in his knee, but there were a few we tried that didn't maintain the "good" that GS500 does for him(osteobiflex comes to mind).
I'm sure that body chemistry has something to do with how an individual pill breaks down in your body.
As for me....I'll keep buying GS500 because I want to keep him skiing with me and it works for him.
Hope this helps.