What Happens To Protein When It Is Digested And Absorbed
One large misunderstanding is that when we consume proteins, they are broken down into “protein molecules” and then sent to where protein is needed.
This isn’t the case. By the time protein has been digested and absorbed and used in your body, it is in a completely different form than what it was when it came in. It’s been fully broken down and fully rebuilt, into whatever the body needs at that time.
You don’t have egg protein molecules or whey protein molecules in your muscle, and you don’t have powdered collagen molecules in your skin or bone.
When you consume protein it goes through a very exact sequence of actions.
First, your stomach breaks it down.
Between your stomach acid and digestive enzymes, the proteins you ate are pulled apart from each other and then the individual chains are uncoiled and broken apart.
They aren’t broken into individual amino acids here, but into much smaller, uncoiled chains of about 20-40 amino acids in length.
From your stomach, they then go into your small intestine, where new enzymes are released.
These new enzymes break the smaller chains of amino acids down further, until all bonds holding the amino acids together have been fully dissolved, and each amino acid is free-floating, unconnected to any other amino acid.
So now, from complex proteins joined together in the form of meat or eggs or soy or collagen, we’ve completely broken these down into tens or hundreds of thousands of individual, unconnected amino acids.
At this point, these amino acids can be made into any of the twenty-thousand-plus forms of protein your body requires.
These individual amino acids are then absorbed through the walls of your small intestine, pass through your liver, and are released into the bloodstream where they can be absorbed by individual cells throughout the body and joined together (synthesized) into new proteins of the exact type or types needed by that cell.
And this is where calories, and how much of the protein we eat is actually used, comes in.
Because these cells don't need just any type or amount of amino acids to make new proteins. They have very exact needs.