Protein is a much-misunderstood topic in our society. In this article, you will learn the role of protein in the body, where it comes from, and whether we need animal foods to obtain enough. But first, we should answer the most basic question: what is protein? A protein is any one of a group of complex organic, nitrogenous compounds that form the principal constituents of the cell protoplasm. You can think of proteins as making up the "guts" of the cells that are the building blocks of our body. Put another way, proteins make up many of the structural and functional components of our cells. For example, they can act as organic catalysts in the form of enzymes, messengers such as peptide hormones, antibodies protecting us from microorganisms, or carrier agents in our Glyco Care blood sugar formula transporting oxygen and other gases. All proteins are composed of specific combinations of amino acids. An amino acid is any one of a class of organic compounds containing a certain amino and carboxyl group.
Although there are dozens of naturally occurring amino acids, the proteins in our body are derived from just twenty. Of these twenty amino acids, our body can adequately synthesize eleven internally. The other nine, called essential amino acids, must be obtained from our diet: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, Glyco Care blood sugar support threonine, tryptophan, and valine. Importantly, although our bodies cannot produce the essential amino acids, they can recycle them. We will explore the implications of this concept later. For now, understand that the diet must provide enough essential amino acids to replace everyday losses. These obligatory losses occur following the use of amino acids to produce things like purine bases, creatine, and epinephrine, which are eventually excreted from the body after serving their purpose. Without dietary sources of the essential amino acids, the body’s protein reserves become depleted, eventually leading to death. The proteins of plants and animals are useless to us unless we can break them down into their constituent amino acids and absorb them.
This is a key concept: our digestive systems cannot absorb large protein molecules, only the smaller amino acids and peptides. Once absorbed, these amino acids become the raw materials from which our body can synthesize the many proteins that serve many vital functions. Dietary protein digestion begins in the stomach with exposure to the enzyme pepsin, Glyco Care blood sugar formula which is secreted in the digestive juices and activated by hydrochloric acid. Contrary to popular opinion, hydrochloric acid does not digest protein but merely creates an appropriate medium for pepsin to work. Following the secretion of hydrochloric acid, the pancreas and the mucosal cells of the small intestine produce other protein digestion factors (proteolytic enzymes). Once the dietary protein molecules have been broken down into their constituent amino acid components, absorption can take place through the mucosal cells of the small intestine. At this point, the body is dealing with more than the amino acids contained in whatever food it has just ingested, because eating stimulates the digestive tract’s secretion of endogenous protein derived from the sloughing of intestinal cells and used-up digestive enzymes.
These recycled proteins are a rich source of essential amino acids. This mixing of endogenous and dietary protein is another key concept. Until it was discovered, people generally believed that to absorb and utilize the essential amino acids in the diet, the diet must contain all the amino acids in certain proportions, presented at the same time. Studies by Nasset demonstrated that this was not the case and that regardless of the amino acid mix of a meal, the intestinal tract maintains a remarkably similar ratio of essential amino acids. This mixing of endogenous protein is the body’s way of regulating the relative concentrations of the amino acids available for absorption. We now know that this reutilization process plays a major role in maintaining the balance of amino acids in the body. By this recycling mechanism, the body can take "incomplete" proteins and make them complete. These concepts are not new-they were reported in the 1983 edition of Modern Nutrition in Health and Disease-yet many people still do not understand them.
Once absorbed, the combination of endogenous and dietary protein passes to the liver by the portal vein. The liver monitors the absorbed amino acids and adjusts their metabolism rate according to bodily needs. The mistaken belief that a diet must contain all the amino acids in certain proportions, presented together, dates back to 1914 when Osborn and Mendel studied the protein requirements of laboratory rats. Their finding that rats grew faster on animal protein than on vegetable sources was followed up by more rat studies by Elman in 1939 using purified and isolated amino acids. This earlier research did not even deal with amino acid absorption, and it falsely stated that the essential amino acids must be present at the site of protein synthesis within the liver, kidney, or muscle cells. Not yet understanding the recycling effect of the body’s amino acids, they assumed that the only source of protein was the diet.
