Medical science often moves in mysterious ways. New treatments may turn up when least expected - or from surprising sources.
One of those unexpected 'new' treatments is glucosamine. People have been using it for more than 20 years, with the first research reports on it dating from the early 1980s but it's relatively new to mainstream medicine.
Now, despite initial misgivings, most doctors are seeing it as quite a good treatment for joint pain and inflammation, which is the suffering brought on by arthritis.
So what is it - and how effective is it? Glucosamine is a compound made up of a nitrogen and hydrogen molecule (the amino part) joined to a simple sugar. It's a key part of the biochemical route needed to build and repair basic tissue in cartilage.
Cartilage is the white slippery substance that lines joints and keeps them moving smoothly. When it wears down or becomes inflamed, joints stiffen and become painful to move.
Glucosamine is widely found in humans and other animals. The version found on our pharmacy and health food store shelves comes from chitin, the hard outer covering protecting shellfish.
Veterinarians have been using glucosamine quite extensively. When more preparations became commercially available in the 90s, people with arthritis - many of whom suffered from the side effects of their usual drugs - began trying it.
Soon it was being touted as a wonder drug, and researchers set out to test the claims. This is where the story gets interesting. Two large reviews of all the previous studies of glucosamine were done and published in 2000 and 2001 in prestigious medical journals - The Lancet and The Journal of the American Medical Association.
Both studies found that while glucosamine does not cure arthritis, it does reduce pain and inflammation. It also does this just about as well as traditional medical treatments.
Possibly most importantly, glucosamine doesn't show much in the way of side effects, one of the big problems with non-steroidal, anti-inflammatory drugs. These can cause stomach and gut bleeding if overused.
So should we all swap to glucosamine? Not yet. It's not clear how it works yet and it also comes in a number of different forms. Some products are also less pure than others. The usual dose is 1,500mg, or three 500mg tablets per day. But even that is not confirmed as the best dose.
The US National Institute of Health is undertaking a large study involving more than 1,000 people taking various combinations - glucosamine, a placebo or chondroitin, another natural supplement.
What should you do about your arthritis now? First, do not take anything until you have talked to your medical adviser. If you are allergic to seafood, do not take glucosamine because it's derived from shellfish. People with diabetes are advised to watch their blood glucose levels carefully because high doses injected into diabetic animals caused problems with blood sugar control.
Meanwhile, do all the other things that help relieve your joints. Lose weight to take the pressure off them, get a regular massage and do regular exercise.