eli5 Protein absorption


I’ve heard from lifters that not complete protein sources (bread,vegan protein powder, fruit) anything without the amino acids, don’t really get used by your body for muscle growth due to the lack of amino’s. So if I eat a sandwhich with a high protein bread and eggs, will my body absorb the protein better because the eggs have those aminos?

In: 2

A meal might have a smaller propotion of certain amino acids, but will contain some amount of them. We never eat just one ingredient, even if not actively trying to balance nutrients, but put something on the bread, wash it down with a drink and have a desert. Those foods complement one another to an extent, such that we don’t feel deficient when eating normally without a diet plan.

There’s no such thing as proteins without amino acids. All proteins (in humans and most other known life) are made of some combination of 20 different amino acids.

You can synthesize some of those amino acids yourself, but there are 9 that you can’t, and those have to come from proteins that you eat. Foods are said to contain *complete* protein when they happen to include all of those 9.

As long as you are eating in such a way that none of those 9 essential amino acids end up being a bottleneck, you’re probably fine.

Answer: There’s something called “bioavailability” of protein:


Before dietary protein can be absorbed, it must be reduced to its essential amino acids in the stomach, then into the small intestine.

Some proteins break down and are absorbed more easily than others. That’s really all there is to it.


There is a bioavailability index for proteins. Whey is at the top at 100+ Wheat is at ~50. Most meats are at ~80.

Amino acids are what proteins are made off. There’s 20 different ones. Some of them our body can make out of other proteins, but some we cannot. These are called essential amino acids.

Humans wants to have a certain ratio of these essential amino acids for our functions, so foods that deviate from those ratios are considered “incomplete” proteins.

Incomplete protein sources are really not a concern at all, unless if you are trying to optimize muscle growth without eating excess protein. But the reality is that the average person is eating about twice as much protein as they actually need to function, meaning that even if those sources are “incomplete”, they still get plenty of each different amino acid.