Right, it depends on the vegan diet. Grains and legume protein are complementary, one deficient in branched chain amino acids, the other deficient in sulfur-containing amino acids, if I recall correctly. I think it’s an easy failure mode of a vegan diet to be all legume protein, and the gluten-free trend has made this even worse, but that’s a rant for the other day. The point here is that when it comes to dietary protein, all that matters is the amino acid composition. Every protein, including collagen, is broken down in the stomach into component amino acids. And that’s why collagen supplements are a scam, and while I am broadly sympathetic to the message of this post I think rationalists should do better.
Every protein, including collagen, is broken down in the stomach into component amino acids. And that’s why collagen supplements are a scam
I was curious about this, and to my surprise found a couplepapers claiming that collagen supplements are incompletely broken down and peptides from them enter the blood and even have effects on the skin. I have no idea if those papers are actually good or if collagen supplements are real, but it’s some indication that ‘proteins are completely broken down into amino acids’ is an oversimplification.
(And if it is an oversimplification, there’s a takeaway like, yes rationalists should learn some science, but should also sometimes double-check before dismissing things based on their understanding.)
((though there are other issues with that passage, like collagen isn’t essential or in any sense a “vitamin”, and a vegan diet will contain zero of it, not ‘technically enough if you eat lots of [something]’))
(ETA: also ‘every protein is completely broken down’ being the whole story is in some tension with food-protein allergies being a thing, and inconsistent with prion diseases being transmitted by food)
That’s interesting—if it’s broken down not into single amino acids, but a mixture of single amino acids, dipeptides, and tripeptides, that still fits with how I understand the system to work; like we’re breaking it down into pieces, but not reliably into single units, sometimes two or three. And then collagen consists of distinctive tripeptide repeats, so the tripeptides you get from collagen are a distinct mixture rather than just random 3-mers, I didn’t think of that. That these tripeptides actually do something is surprising if true, but why not.
I guess what I was thinking was that when you eat collagen, it doesn’t become your collagen. Which seems to be true: your collagen is made at the ribosome from single amino acids, not assembled from the kind of dipeptides and tripeptides discussed in the paper. So it’s not like you get collagen by eating collagen, the way you get vitamin B12 by eating vitamin B12. But if there’s some totally separate biological effect… well, I can’t rule it out.
Right, it depends on the vegan diet. Grains and legume protein are complementary, one deficient in branched chain amino acids, the other deficient in sulfur-containing amino acids, if I recall correctly. I think it’s an easy failure mode of a vegan diet to be all legume protein, and the gluten-free trend has made this even worse, but that’s a rant for the other day. The point here is that when it comes to dietary protein, all that matters is the amino acid composition. Every protein, including collagen, is broken down in the stomach into component amino acids. And that’s why collagen supplements are a scam, and while I am broadly sympathetic to the message of this post I think rationalists should do better.
I was curious about this, and to my surprise found a couple papers claiming that collagen supplements are incompletely broken down and peptides from them enter the blood and even have effects on the skin. I have no idea if those papers are actually good or if collagen supplements are real, but it’s some indication that ‘proteins are completely broken down into amino acids’ is an oversimplification.
(And if it is an oversimplification, there’s a takeaway like, yes rationalists should learn some science, but should also sometimes double-check before dismissing things based on their understanding.)
((though there are other issues with that passage, like collagen isn’t essential or in any sense a “vitamin”, and a vegan diet will contain zero of it, not ‘technically enough if you eat lots of [something]’))
(ETA: also ‘every protein is completely broken down’ being the whole story is in some tension with food-protein allergies being a thing, and inconsistent with prion diseases being transmitted by food)
That’s interesting—if it’s broken down not into single amino acids, but a mixture of single amino acids, dipeptides, and tripeptides, that still fits with how I understand the system to work; like we’re breaking it down into pieces, but not reliably into single units, sometimes two or three. And then collagen consists of distinctive tripeptide repeats, so the tripeptides you get from collagen are a distinct mixture rather than just random 3-mers, I didn’t think of that. That these tripeptides actually do something is surprising if true, but why not.
I guess what I was thinking was that when you eat collagen, it doesn’t become your collagen. Which seems to be true: your collagen is made at the ribosome from single amino acids, not assembled from the kind of dipeptides and tripeptides discussed in the paper. So it’s not like you get collagen by eating collagen, the way you get vitamin B12 by eating vitamin B12. But if there’s some totally separate biological effect… well, I can’t rule it out.