You just hammered that 12 oz. porter steak. Or if you’re a vegetarian, perhaps you had quinoa and legumes. What are the steps of protein as it goes through your body?

Beginning Steps of Protein Digestion

Unlike starches, the stomach is where a lot of the “breakdown” steps happens with protein. As we all know, it’s the low pH of the stomach that does the majority of the work. The acid that’s secreted from the wall of the stomach is hydrochloric acid. This acid denatures the protein.

What is Denaturing the Protein?

Let me first explain that different amino acids join together, some of which like water and some that don’t. Imagine a rope that is in a liquid environment and all the sides of the amino acids that dislike water fold toward the middle. Meanwhile, the sides of the rope that “like” water stay on the outside. The rope then crumbles into a ball shape.

Now you need a hot or acidic environment to unravel (i.e. “denature”) that rope. That’s where the hydrochloric acid in the stomach comes into play!

This acid first unravels (denatures) the rope and activates pepsin. Pepsin is an enzyme which begins to break the unraveling rope into smaller pieces of rope. We call these smaller pieces of rope polypeptides.

Final Stages of Protein

Once the snippets of rope (polypeptides) enter the small intestine, they are further broken down to shorter strands until they are finally broken down into their amino acid components.

The amino acids get carried across the small intestine’s wall into the bloodstream for use wherever needed.

End Product and Uses of Protein Digestion

What do we use the amino acids for? The incomplete list:

  • Tissue repair
  • Growth
  • Tissue replacement
  • Making enzymes
  • Protein turnover
  • Fluid balance
  • Antibodies
  • Acid-base balance
  • Hormones
  • Transport proteins
  • Blood clotting
  • Visual pigments
  • Energy production
  • And so much more!

A normal person’s body is incredibly efficient at this process. Ensuring your body gets all the amino acids it needs out of the protein you eat.