Proteins are the vital components of the human diet. Amino acids, which are released from the breakdown of proteins, are the building blocks of many structures within our body, including organs, nails, and muscles. Amino acids are of two types, essential amino acids, and non-essential amino acids. Non-essential amino acids are those that can be produced by the body from other peptides and metabolites. Essential amino acids are those which cannot be produced by the body and our body and is solely dependent on external sources for these amino acids. Proteins are not directly absorbed when ingested.
They are first converted into peptides and amino acids and then absorbed or assimilated by the body. As we know, there are twenty different types of amino acids. So, only one transport mechanism is not enough for the absorption of all proteins and amino acids. There are various transport mechanisms present in the digestive tract to absorb different amino acids.
- Proteins are large molecules that cannot be digested by the human intestine directly.
- Gastric HCL causes the denaturation of proteins in the stomach. It converts proteins into metaproteins, which are easier to digest.
- Carboxypeptidase acts on a terminal peptide bond, and it is produced in an inactive form known as procarboxypeptidase. It is activated by trypsin.
- Amino acids are absorbed through two different mechanisms. One is the glutathione transport mechanism, and the other is a carrier protein transport mechanism.
How Does Excessive Protein Fermentation Occur in the Gut?
Many microbes in the upper gut the stomach, and the duodenum can increase protein fermentation if overgrown. H. pylori, for example, can ferment protein to survive. H. pylori can increase the pH of the stomach by producing urease, making ammonia for survival, reducing protein digestion, and increasing its fermentation. H. pylori can also reduce stomach emptying time by reducing the function of the vagus nerve, keeping food longer in the stomach, and therefore increasing time to be fermented by bacteria. H. pylori are known to cause stomach bloating, heartburn (gas pushing stomach contents into the esophagus and weakening the LES), and belching produced by excessive protein fermentation in the stomach.