are made up of carbon and hydrogen molecules similar to carbohydrates and fats, but protein also contains nitrogen. The smallest unit of protein is called the amino acid, and when amino acids are joined together, they form what are called peptide chains. These grouping of amino acids are what makes the basic structure of protein. Protein in the body allows for muscle growth and repair, helps to stimulate the immune system and also aids the body in ATP production.
Amino Acid Pool
Without daily intake of amino acids, also known as the building blocks of protein, the body will reach a net negative protein balance, which Dr. John Berardi describes happens when nitrogen output exceeds nitrogen input. The body experiences losses of these amino acids daily, and Berardi compares this idea to the notion of the body being a sink full of amino acids without a drain plug. The only way to replace these amino acids is through dietary intervention. If this amino acid pool is not replenished, key enzymes and other contractile and fibrous proteins are cannabolized, which can eventually cause vital functions to shut down.
The body does not store protein
, rather it takes what it needs from both the amino acid pool and what is derived from food sources and uses it for the necessary functions mentioned. When more protein is consumed than what the body needs, the protein is processed through the liver, filtered through the kidney and then excreted through urine. For this reason, Berardi recommends that women need only to consume 20 to 30 g of protein at a time, and for men, 40 to 60 g is sufficient.
Manufacturing Amino Acids
While the body does not store protein
, it does have the ability to make certain amino acids, also known as the 12 non-essential amino acids. There are eight amino acids that must be supplied by the diet, referred to as the essential amino acids. These amino acids include Pheylalanine, Valine, Threonine, Isoleucine, Methionine, Leucine, Lysine. Consuming foods that contain these amino acids will aid the body optimal protein synthesis and promote muscle growth, a stimulated immune system and help to keep the body energized.
Incomplete and Complete Proteins
Protein quality is a measure that ranks protein sources based on the availability of their amino acid profile, and can be useful in developing a well-rounded nutritional regime. Complete proteins are those that have been measured through various scales including the Biological Value scale, Net Protein Utilization scale or Protein Efficiency ratio scale that provide all of the essential amino acids in sufficient amounts. These include eggs, meat, fish, poultry, milk and cheese. Incomplete proteins contain a lower amount of essential amino acids, and is usually found in plant sources. Some plant sources can be combined to make a complete protein, and there are a few plant sources such as quinoa, buckwheat, hempseed and amaranth that have been rated complete.