On the subject of collagen being effective, its a hard thing to test besides Range of Motion changes. However, there have been measured tests on skin elastically in people and mice subject to collagen use.
***I would guess its effectiveness depends on *current gut health and gene****. You can take everything in the world as far as nutrition goes, but its effectiveness is not guaranteed the same with everyone.
Collagen is a protein made up of amino-acids: glycine, proline, hydroxyproline, and arginine.
And you can get these aminos in plant form to make your own collagen:
https://www.biospace.com/article/releases/plant-based-collagen-building-protein-peptides-now-available-from-sunwarrior/But will your body do this correctly?
My bodies soft tissue was pretty "wrecked" from years of a couple combinations of endurance sports coupled with impact injuries, all the while with lyme getting worse and worse for decades. Im sure there's better test subjects, but I fit that descript
ion pretty good.
After using many different proteins, body building formulas, individual aminos, and various similar supps, then comparing to others experiences, all I can say is what works for us individually differs. So far the best thing that has made results for myself is creatine and Dr Axe collagen (5 types in one) powder. the whey, egg, and plant protien powders where of no noticable benefit to me for some reason, but might be for others.