Welcome to our Knowledge Base
< All Topics

Protein digestion and absorption

Digestion and absorption of protein in the Human body

Digestion in the Stomach

Protein is a necessary component of the human diet. It can be found in foods such as meats, eggs, nuts, and dairy. Whatever protein we take, it is broken down and rebuilt into proteins that our bodies can utilize. These proteins have a wide range of functions in the body, from cell division to infection resistance. These proteins are a chain of amino acids linked together by peptide bonds, much like a string of beads. Protein is broken down into distinct amino acids when we eat it. When dietary proteins are ingested, they denature owing to stomach acidity, revealing a three dimensional structure and the polypeptide chain. This is the initial step in the digestion of proteins. Denaturation in the stomach inhibits protein function since a protein’s three-dimensional shape is essential for it to function. When proteins are denatured, the bonds that connect the amino acids become more accessible for digestion. This process is initiated by pepsin, an enzyme secreted by the cells lining the stomach and activated by hydrochloric acid. Pepsin begins to degrade peptide bonds, resulting in shorter polypeptides (see fig-1). Proteins are big molecules that require time and mixing to chemically degrade. Protein digestion is slower than carbohydrate digestion but faster than fat digestion. Eating a high-protein meal increases the time necessary to break down the food. Food remains in the stomach for a longer amount of time, making you feel fuller for longer.

Digestion in the Small intestine

Following this, the chyme exits the stomach and enters the small intestine, where the majority of protein digestion happens. The pancreas secretes digestive juice into the small intestine, which contains additional enzymes to aid in the breakdown of polypeptide bonds. Chymotrypsin and trypsin are two key pancreatic enzymes found in this fluid. Trypsin is used to activate proteases, which are enzymes that degrade proteins. These enzymes degrade protein into amino acids. Tripeptides and dipeptides are the two most important. These amino acids enter the enterocytes of the small intestine via the active transport mechanism. Once inside the enterocytes, the tripeptides and dipeptides are broken down into single amino acids, which are absorbed into the bloodstream.

Table of Contents