I wonder why we need to supplement glucosamine (e.g. to treat arthritis) when it is synthesised by the body from glucose in one of our basic metabolic pathways. I could only imagine this becomes a problem unless a) the enzymes responsible stop working or b) if the glucose gets shunted off to some other purpose.

It’s also funny that chondroitin supplementation does the job too, because it actually contains no glucosamine, but contains monosaccharides that are derived from glucosamine (N-acetyl Galactosamine).

I think there’s probably a very interesting answer to these metabolic questions that could shed a lot of light onto the phenotypes of aging. That said, I don’t know what evidence is out there for systemic lack of e.g. glycosaminoglycans in aged populations, or even in arthritic cohorts.