The blue-green algae(BGA) which I am now taking regularly makes new collagen in my body. Why take collagen to substitute the lost collagen in our body? It is not the right way. Our own collagen is the best if it is being produced within our body. Animal collagen is the last thing I want to put in my body!
When one gets older the body produces less collagen. Same thing happens with CoQ10 production, as we age our bodies do not produce enough C0Q10.
Taking supplements is to aid the body.
Decision on vegetarianism is a personal thing. However it does limit your options on the supplements you can or cannot take.