JointsAid declares its five ingredients as one 1,398 mg proprietary formulation. That gives you the running order by weight and nothing else — no individual quantity for any of them. The four below are the ones most often asked about, either because they carry the most research or because they carry a caution.

Glucosamine
Glucosamine sulfateA compound the body makes itself and uses in the structures that cushion and lubricate a joint. Supplemental glucosamine is usually produced from shellfish shells, though corn-fermented versions exist; JointsAid does not state its source.
What the research looks at. It is the most studied ingredient in this whole category and the most argued over. Some large independent trials found a benefit in more painful knees; others found nothing beyond placebo. Nobody treats the question as settled.
Worth knowing. If you have a shellfish allergy, ask the manufacturer about the source before ordering. Do not assume it is plant derived because the marketing says plant based.

Turmeric
Curcuma longa rootThe rhizome that gives curry its color. Its active fraction, curcumin, is among the most researched plant compounds there is.
What the research looks at. Human trials examine it for an inflammatory response already inside the normal range, and for joint comfort alongside it. The persistent weakness is absorption: plain curcumin is poorly taken up unless something is done to help it.
Worth knowing. It can add to the effect of blood thinners and may upset a sensitive stomach at higher intakes. Worth mentioning to a prescriber.

MSM
MethylsulfonylmethaneAn organosulfur compound present in small amounts in plants and in the human body. It turns up in most joint formulas on the market.
What the research looks at. A handful of small, short, controlled trials in knee discomfort and in soreness after exercise. The direction is encouraging but the studies are too small and too brief to call it established.
Worth knowing. Generally well tolerated. Mild digestive upset is the usual complaint and usually passes.

Boswellia Serrata
Indian frankincense resinResin tapped from a tree native to India and used in Ayurvedic practice for centuries before anyone ran a trial on it.
What the research looks at. Of the five ingredients here, this has some of the more consistent human data for joint comfort and morning stiffness. The trials are still small, and different studies use different standardized extracts, so results do not transfer neatly between them.
Worth knowing. It is also on the list of botanicals that can interact with blood thinners. Same conversation with a prescriber applies.
The fifth is quercetin. A plant flavonoid from onions, apples and capers. Its antioxidant activity is well characterized; the work on inflammatory signaling is mostly laboratory and animal research rather than human trials. It sits in the homepage panel with the rest.