definition of complete and incomplete proteins reddit
Answers
The concept of a "complete protein" and "incomplete protein" is not really what it seems. Proteins from nearly every source contain all of the essential and inessential amino acids. The difference is the amount of amino acids they contain.
This has developed the idea of the "limiting amino acid" which is simply the AA that is in the least supply within the group.
The limiting amino acid in rice is lycine (while being high in methionine) and the limiting amino acid in beans is methionine (while being high in lycine). Combine the two and we have a more "complete" amino acid profile. This is why vegetarians often talk about complete and incomplete protein sources. However, the concept of "complete proteins" is really only a matter of concern in people who exclusively eat something like rice (in 3rd world countries, for example), and end up having a protein deficiency which causes all kinds of issues.