Agree. Quercetin did help with recovery, but so did eating the equivalent amount of foods that contain it: Red Onions, Red Grapes, Berries, dark green veggies. Rather a lot of those of course, about 1 to 1.5 kg combined. I remember the clinically effective dose to fight colds and so on to be 500mg, but my body dumped quite a lot of that into the toilet, so I halved the dose on another occasion and the effect was the same and I recovered quicker that when not taking it. But again, those foods in adequately high amounts did enough, probably because they also give energy, vitamins, minerals as well.

Agree on the collagen as well, especially for recovery after injuries and after surgery.