Can the collagen we take from outside actually reach our skin? I do not hesitate to say this not only for collagen but for all supplements: to see the effect of something you take, you first have to question the ground it lands on, that is, the body.
Are we eating well? Is our sleep in order? How much are we working our muscles and exercising? As long as the foundation is not sound, whatever you take from outside will not work in the body.
If the foundation is sound, then you can see the benefit of the supplement you are using, in your skin and in your daily energy. But neither collagen nor any other supplement is a magic wand on its own.