All five ingredients sit inside a single declared 1,398 mg proprietary formulation. What that buys you is a ranking by weight and not one gram figure for anything in it. The four covered below are the ones readers ask about, either for the depth of research behind them or for the warning that travels with them.

Glucosamine
Glucosamine sulfate
A structural building block the body manufactures itself and uses in the tissue that pads and lubricates a joint. Supplemental glucosamine is usually produced from shellfish shells, though corn-fermented material exists; JointsAid does not say which it uses.
What the research examines. Nothing else in this category has been tested as often, and nothing else is argued over as much. Some large independent studies reported an effect in more painful knees while others found nothing beyond placebo. Nobody treats the question as settled.
Worth knowing. With a shellfish allergy, ask the manufacturer about the source before ordering. Do not take plant based on the marketing and assume it covers this ingredient.

Turmeric
Curcuma longa root
The underground stem responsible for the color of curry. Its active fraction, curcumin, is among the most researched plant compounds in the literature.
What the research examines. Human trials examine joint comfort and an inflammatory response already inside the normal range. The standing difficulty is absorption: curcumin on its own is taken up poorly unless something is done to help it along.
Worth knowing. It can add to the action of a blood thinner and may upset a sensitive stomach at higher intakes. Worth raising with a prescriber.
A sulfur compound present in trace amounts in plants and in the human body, and a near-standard companion in joint formulas.
What the research examines. A handful of short, small controlled trials in knee discomfort and in soreness after exercise. The direction is encouraging; the sample sizes and durations do not support a firm conclusion.
Worth knowing. Most people tolerate it without trouble. Mild digestive upset is the usual complaint and it tends to settle.

Boswellia Serrata
Indian frankincense resin
Resin tapped from a tree native to India, in use in Ayurvedic practice for centuries before anybody built a trial around it.
What the research examines. Among the five it holds some of the steadier human findings for joint comfort and morning stiffness. The studies stay small, and because each uses a different standardized extract the results do not carry cleanly from one to the next.
Worth knowing. It appears on the list of botanicals that can interact with a blood thinner. The same conversation with a prescriber applies.
Quercetin is the fifth. A dietary flavonoid found in onions, apples and capers. Its antioxidant activity is well described, while the work on inflammatory signaling sits mostly in cell and animal models rather than in people. It sits with the rest in the homepage panel.