Glucosamine and Chondroitin 1500mg x 180 tablets Both these ingredients are held in high esteem generally. Glucosamine is highly rated among local Brazilian Jiu Jitsu heads - and let's just say (based on my observation of them not personal participation), if you don't want to tear your joints up, don't do BJJ - so if those nutters rate it...
I also take hyaluronic acid which some rate.
My doddery mother swears by cod liver oil capsules as do many.
As for whether you should be taking such things, think you'll struggle to find consensus. Very little scientific evidence on this stuff. Personally I'd say if you can afford it, why not take at least the most credible stuff (like my first link). Let's just say a lot of trainees report joint problems over time.
Only risk is some nasty side effects on the system from taking this stuff, I've heard nothing whatsoever about that and would guess it's very low risk. You always wanna go with a quality supplier though.
Finally I'll mention that some people find high rep routines helpful for their joints (like 25 reps), and others like slow eccentrics (3 second lowering phase). Both of these things subject to a lot of debate and different people respond differently. I think slow eccentrics have more scientific backing for what its worth (scientific studies not the be all, not all has been studied)
good luck with your training