For example: it's amazing to me how many facial products such as face masks contain collagen.
Do people think that your body just takes collagen from your epidermis and adds it to your skin?
That doesn't mean that eating muscles makes you muscular though obvs (any more than eating mussels makes you mussel-ar)
Yea that's what I meant by literal, as in you aren't a pig if you eat pigs, you aren't muscular if you eat muscle. You are made up of the building blocks of the thing you ate, but that does not make you the thing itself.
Maybe literal wasn't the right word? Anyways, doesn't really matter.
Hydroxyproline is conditionally essential, particularly in older and injured populations, and collagen is a rich source of it. Research has demonstrated that collagen supplementation reduces arthritis symptoms and increases collagen synthesis. That being said, unless you're getting 15+g of collagen (the amount used in one study I recall) in your bone broth it probably isn't doing much.
Protein up to a point improves protein synthesis, and it also has the nice side effect that it is inefficiently stored as fat, both from a thermodynamic and hormonal standpoint. So a random high protein diet is more likely to get someone "ripped" than a random low protein diet.
The number of these commercials that claim something is good for you because it has some random, natural oil in it, is staggering. There's plenty of natural acids that will melt you into a pile of goo. i wouldn't want to put those on my face.
This assumes the enzymes are functioning correctly and have the capacity to synthesize more collagen.
These mechanisms are well understood and elucidated in good biochemistry and nutrition textbooks.