Yes they do.

Yes, the mechanism by which amino acids are absorbed is conceptually identical to that of monosaccharides. The lumenal plasma membrane of the absorptive cell bears at least four sodium-dependent amino acid transporters - one each for acidic, basic, neutral and amino acids. These transporters bind amino acids only after binding sodium. The fully loaded transporter then undergoes a conformational change that dumps sodium and the amino acid into the cytoplasm, followed by its reorientation back to the original form. Thus, absorption of amino acids is also absolutely dependent on the electrochemical gradient of sodium across the epithelium. Further, absorption of amino acids, like that of monosaccharides, contributes to generating the osmotic gradient that drives water absorption.

The basolateral membrane of the enterocyte contains additional transporters which export amino acids from the cell into blood. These are not dependent on sodium gradients.

Thanks a lot!!

I am no specialist on this topic but I read that even some peptides are absorbed by the epithal but still are changed inside the epithal and only amino acids are going into the blood system. The question is if creatine, or hydrolized peptides such as collagen are going into the blood in that way or not?

Many thanks will read the documents one day

Agree with Dr. Koi Hayakawa.

Wow thanks for the answer. To not eat egg white is something to claim, especially when you are sport scientist as me. Some people claim egg yolk is bad with cholesterol. I heard about avidin however. It seems with digestion there is so much more happening than we (sport science) might imagine. I hope experts on digestion and sport scientist can coöperate more.

Thanks

Thanks for the answer. I am no specialist on the matter. Just a self-educated "scientist".

If I am correct you prove that β- Lactoglobulin is not digested into amino acids. So it can be that proteins or peptides be absorbed in whole.

So in case of collagen this could (?) also be absorbed at whole.

But if I measure collagen, and ingest collagen it can still be broken into amino acids and be constructed in the body again. So how can I track (not that I can, but hypothetical) the collagen from ingestion to actually being at the place it should be, for instance at my wrist injury?

It is important because some fabricants will claim that nutrients are ingested and absorbed as a whole. So hydrolyzed polypeptides would be quicker digested (which is true I assume) and absorbed (that I question). Even if they are absorbed into the enterocyte I red somewhere they can be broken down there further. So in the end it would be amino acids in the systemic circulation. So the collagen would just be amino acids in the end. So a normal diet would also lead to the same potential, that is amino acids in the blood circulation.

I am reading a lot, so maybe soon I will understand the topic better.

Many thanks again.

The mechanisms involved in the absorption of amino acids and oligopeptides are reviewed regarding their implications in human feedings. Brush border and basolateral membranes are crossed by amino acids and di-tripeptides by passive (facilitated or simple diffusion) or active (Na+ or H+ co-transporters) pathways.