Proteins are responsible for most of the catalytic and regulatory activities in the body. What is important is not just the quantity eaten but its quality. One may have a high protein intake but still be deficient regarding certain amino acids.
In the diet Proteins are initially broken down in the stomach. The enzyme pepsin breaks down the protein into smaller polypeptides and amino acids. This process is continued within the small intestine, where the pancreatic enzymes trypsin, chymotrypsin and elastase continue the process.
These are then assimilated into the body. The amino acids are transported throughout the body for protein synthesis. Amino acids in excess of needs are unable to be stored, so any excess is converted to glucose or Ketones, or are broken down and any excess ammonia created is excreted by the body in the form of urea.
Food will have a different combination of amino acids. Some foods are considered complete proteins in that they contain all of the essential amino acids required. Many amino acids are considered non-essential because the body is able to synthesise them as quickly as they are utilised. Foods that are considered complete proteins are generally found in animal sources. Soybeans and Quinoa also contain all the essential amino acids. The body does not require that all the essential Amino acids come from the one source as long as the diet contains them within the variety of foods eaten.
Essential Amino Acids;
Phenylalanine, Isoleucine, Leucine, Valine, Threonine, Methionine, Lysine, Tryptophan, and Histidine (Required in childhood and growth periods. As demand exceeds production during these times.)
Non-Essential Amino Acids
Alanine, Glycine, Selenocysteine, Arginine, Ornithine, Aspartic acid, Proline, Creatine (energy storage), Cysteine, Serene, Citrulline, Tyrosine, Glutamic acid, Asparagine, Glutamine, and Taurine.
For more information go to AminoAcidsGuide.com.
Protein is involved in a number of regulatory functions, such as: Growth, hormones, enzymes, cytokines, transcription factors and also neurotransmitters. Protein is required for the immune system, and can act as transport carriers in the blood. Protein is also involved in fluid balance, PH levels, detoxification and energy. Some protein enzymes, such as kinases and phosphatases act in a regulatory manner through controlling the action of other enzymes. There is no specific storage of protein in the body but the breakdown of muscle will serve as a fuel reserve in times of energy needs. During protein metabolism the amino acids which make up the protein are broken down and the nitrogen content, which is toxic to the body, is eliminated through the urine.
The amount of daily protein required is usually calculated as 0.8 - 1.0 g per Kg of body weight.
An important distinction needs to be made between two aspects of protein, that is, protein quantity and protein quality. Protein is broken down through digestion into its constituent amino acids and then absorbed. The amino acids have been traditionally divided into essential and nonessential. However many of these nonessential amino acids can be further differentiated as conditionally essential. In that it is possible to be deficient if the body is unable to synthesise them. This may be due to the body's needs being greater than its ability to synthesise the relevant amino acid. For example cystine plays an important anti-inflammatory and antioxidant role. Increased exposure to toxins may increase the body's need to utilise more cystine than it is able to produce.
A number of nonessential amino acids are involved in detoxification. The branched chained amino acids: leucine, isoleucine and valine can be oxidised in the mitochondria to provide energy. Creatine and carnitine also play key roles within energy production. Creatine is stored in muscles as phosphocreatine and helps in the regeneration of ATP, (Adenosine Triphosphate) the energy currency of the body. Carnitine helps to transport fatty acids and pyruvate into the mitochondria to be used for energy production. Arginine generates Nitric Oxide and is involved in the Urea cycle which enables the body to dispose of excess nitrogen. Taurine and Glycine play an important role in detoxification. While Cysteine also plays an important role in converting Homocysteine into Methionine. High levels of Homocysteine are related to cardiovascular disease, while Methionine plays an important antioxidant role and is involved in detoxification. Glutamine combined with Alanine transports Nitrogen. Glutathione; produced from Cysteine, Glycine and Glutamic acid is an antioxidant. It is produced in cells and possess many benefits. It reduces oxidative stress, supports immune function, contributes to the making of DNA, supports enzyme function, regenerate vitamins C and E, and regulates prostaglandin synthesis as well as many other functions. While the body is able to synthesise Glutathione, its level can drop with age and poor diet.
The amino acid Glutamate acts as an excretory neurotransmitter in the brain, and is involved in; memory, cognition, movement and sensation. Gamma-Aminobutyric Acid GABA acts as an inhibitory neurotransmitter. While Aspartate acts as an excretory neurotransmitter and Glycine inhibitory. Glutamate and GABA account for 90% of activity.
Sometimes a protein or a peptide can cause an allergic reaction, invoking an immune response. A person may be intolerant to certain proteins due to not having the requisite enzyme to break it down. For example lactose found in milk and dairy products. Without the enzyme lactase, lactose is not broken down and ferments in the stomach causing bloating, flatulence, and diarrhoea.
An Elimination diet can be beneficial in identifying the underlying cause and relieving the symptoms of foods that initiate an allergic response.