I was reading an article about whey vs casein, which said casein is digested very slowly. I remember reading casein peptides in the blood stream are used by the body in a much slower way. I've a confusion between the terms digestion and blood absorption, when we say something is digested does it mean that the food is completely broken down and taken into blood or the process still continues in the blood stream.

What I want to know is protein from different sources (meat/whey/casein...) when entering the blood stream after digestion in the intestines are essentially in the same form or each one absorbed into the blood stream is in a different form which is further broken down in the blood stream.

1 Answer 1


Digestion is the body's process of breaking down food that we've partially digested in our mouths into macro nutrients it can properly absorb.

Absorbtion is the bodies utilization into the blood stream of those macro nutrients broken down through digestion.

Whey is the smallest and easiest protein for th ebody to absorb.

Soy is in the middle.

Casien has the longest absorption rate.

All proteins are nothing more than a different blend of amino acids. They way they are grouped determines their absorption rates.

Answer to your question: Yes, proteins from different sources will be absorbed into the blood stream at different rates, because at a macro level, their branched chain amino acid groupings will be different. Many of the same parts, but put together differently, so absorbed differently.

Good Article: http://library.thinkquest.org/11226/main/c14txt.htm

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