Ace the ISSA Nutritionist Exam 2026 – Fuel Your Future with Flair!

During digestion in the stomach, protein is primarily broken down by hydrochloric acid and digestive enzymes. The stomach secretes hydrochloric acid, which creates an acidic environment that denatures the protein molecules, unraveling their complex structures. This process is essential because it exposes the peptide bonds of the proteins to enzymatic action.

The enzyme pepsin, which is activated in this acidic environment, further breaks the denatured proteins into smaller peptides. This reduction in size is crucial for the subsequent stages of digestion that take place in the small intestine, where these smaller peptides continue to be broken down into amino acids for absorption into the bloodstream.

The other options do not accurately describe the role of the stomach in protein digestion. While proteins do eventually get absorbed into the bloodstream, this occurs mainly in the small intestine, not the stomach. Proteins are not converted into carbohydrates during this process; instead, their primary role is to provide amino acids. Lastly, proteins do not remain intact; they undergo significant breakdown in the stomach before any further digestion occurs in the intestines. Thus, the accurate description of what happens to protein in the stomach during digestion is that it is broken down by hydrochloric acid and enzymes.