Naurthon wrote:...glucosamine...does not carry FDA approval in general, so I'd be very surprised if anyone would bother with the expense of safety and efficacy testing because they aren't legally required to.
In general, IMHO, most "nutritional supplements" have insufficient scientific evidence to support their IMPLIED benefits (directly stated claims require FDA approval), and that's with humans.
The FDA approves foods and medicines because they are dangerous. (i.e., aspirin, tylenol, etc.) If a substance isn't dangerous, the FDA doesn't need to approve it, and then there's no FDA validation of the company's claims.
There have been lots of studies on many nutritional products, but you don't hear about them because most of them are published in scientific journals which are mostly read by doctors and not the general public. These studies are usually available for the public to read, but you have to look them up and most people would rather be watching football instead. I won't go into the animosity between pharmaceutical companies and nutritional supplement manufacturers here - that's a whole other can of worms that might get me in hot water.
There have been numerous studies on glucosamine as a natural medicine and its benefits for people and animals, but I don't know if it could be given to birds because
1) there probably hasn't been any studies showing if it does anything for birds
and 2) lots of things that humans and animals can eat just fine are toxic to birds. (However, since glucosamine is occurs naturally in tiny amounts in some foods, this might be a different case.)
In my personal experience, we had a dog with hip displasia, and she would be stiff and lame if we forgot to give her a dose of glucosamine supplement the day before. I take glucosamine myself, especially after exercising or doing lots of hiking because when I don't take it, my knees give me trouble (and I'm only 18!) So I swear by the stuff!
[Source: my dad's a doctor and he lectures me on health stuff
all the time. hahaha]