What Is Protein & What Amino Acids
Do You Need?
What is a complete protein and how does it relate to natural health and diet?
To start, the basic definition of protein is that proteins are long chain molecules made up of amino acids joined by peptide bonds. Next to water, protein is the most plentiful substance in your body and is the principal constituent of the protoplasm in every cell of your body. That said, there is not just one kind of protein, but many kinds in the human body, each with a different function. For example, different proteins can:
- Provide structure, as found in ligaments, fingernails, and hair
- Aid in digestion in the form of digestive enzymes
- Play a role in immunity in the form of immunoglobulins
- Aid in building muscles
- Tell your body what to do and when, as seen in peptide hormones
- Transport oxygen as hemoglobin
- And even play a role in our ability to see. The lens of the eye is pure crystallin protein.
How The Body Utilizes Protein To Build Muscles
Interestingly enough, your body does not actually utilize protein directly when you eat it. When you consume protein, for the most part, the body breaks it down into its constituent amino acids, absorbs those amino acids through the intestinal tract, and then using genetic instructions encoded in your body, reassembles them into the proteins it needs to perform all its functions. For example, it takes dairy protein you eat, breaks it down in the digestive tract into its constituent amino acids, absorbs those amino acids, and then reassembles them into muscle protein to help you build muscle. Thus, milk protein, if properly broken down, eventually leads to more muscle mass and proteins for bodily functions.
When the body assembles a protein from amino acids, such as when it builds muscle, it needs a variety of amino acids to complete the process. Some of these amino acids may be produced in the body itself. Others may come from dietary sources such as pea and rice protein. But the nine essential amino acids can only come from dietary sources because your body cannot produce them no matter what you eat. These nine are considered essential, not because they're more important, but again because your body cannot manufacture them and therefore they must be part of your diet on a regular basis. These include:
- Histidine (your body can manufacture histidine, but usually not in sufficient amounts)
If your diet is chronically deficient in any one of the essential amino acids, the building of protein in the body stops, which brings us to a key point. Your body's ability to utilize protein is profoundly affected by the "limiting amino acid" in your diet -- in a nutshell "you're only as strong as your weakest link." For example, if you are vegetarian or vegan and rely only on rice for your protein, which tends to be low in lysine, your diet will not offer a healthy balance of protein. Over time, the lack of lysine in your diet may become a limiting factor in the ability your body has to assemble complete proteins. Simply adding legumes, which are high in lysine, to the diet corrects the problem and allows your body to build all of the proteins that it needs. It is a good idea, therefore, to mix your protein sources so that deficiencies in any one source are corrected by another. In addition, this limits the loss of nitrogen in the liver where amino acids are broken down, thereby releasing ammonia and causing an increase in the production of uric acid. Bottom line: getting a good mix of essential amino acids from your protein sources increases your overall net protein utilization and reduces the chances of gout.
To summarize everything that we've covered so far, let's just say that protein, as a category, is one of the essential nutrients along with carbohydrates, fats, vitamins, minerals, oxygen and water. In fact, the word protein comes from the Greek word "prota," meaning "of primary importance." Protein has a critical physiological function. It is primarily used in the body to build, maintain, and repair body tissues. In some cases, if protein intake is greater than that required by the body to perform its primary function, the excess protein may be converted to energy for immediate use as happens with bodybuilders and performance athletes.