Ken Ward's Health and Nutrition PagesProteins |
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What are Proteins?Proteins are well known as food that build body structures and organs. They are highly concentrated in muscles. Chemically, they consist of carbon, oxygen, hydrogen and nitrogen. They are made of strands of amino acids. Some amino acids contain sulphur. What do proteins do?Proteins are important:
Growth and MaintenanceProteins are the building blocks of body tissues, membranes, skin, ligaments, bones and organs. They are therefore important for growth in children, and for repair and maintenance of the organs of both adults and children. It is required for hair and nail growth and for new blood cells. When the body is stressed - either through disease or injury, or due to external threat - it requires massive amounts of protein. Building Enzymes and HormonesSome enzymes and hormones in the body are proteins, so the body requires proteins to replace and build them. Proteins are used, for example, to make:
Building AntibodiesProteins are used to build antibodies, which are themselves proteins that recognize proteins belonging to the body and those which don't belong (such as bacteria and viruses). Antibodies are made to deal with one specific threat only. They will deal with one strain of bacteria, but not with another. They also destroy the alien protein (and the body remembers how do this). Therefore, next time the threat arises, the body can respond faster because it remembers how to make the antibody. Maintaining Fluid BalanceCells require a balance of water and chemicals. If they are deprived of water or have too much, then they die. Proteins control the fluid balance in cells. They also control the chemicals, such as salt and potassium, inside and outside the cells, so the right balance is maintained. If this process fails, the heart and the nervous system are in great difficulty! To Maintain acid-Alkali balanceThe blood needs to transport the waste products of cells - which may be too acid or too alkaline - to the liver or kidneys, for elimination. This waste material needs to be transported without changing the acid-alkali balance of the blood. To do this, blood proteins take in the extra hydrogen and hold it until the blood needs to be made more acid. In this way, proteins control the pH of the blood. If the amount of acid is to great, then the proteins in the blood become overloaded and misshapen. When there is too much acid in the blood, a condition known as acidosis occurs; and when there is too little, a condition known as alkalinosis occurs. Provide EnergyNormally carbohydrates are the main source of energy in the body, however, protein molecules can be broken down to make glucose, and the nitrogen part turned into urea. Fats cannot be broken down in this way, so when there is a shortage of energy that carbohydrate cannot supply, then protein is used. If energy is not available from carbohydrates, then proteins and fats are used up. When this occurs, protein is lost as well as fat, which may mean damage to organs, and tissues as well as to the immune system. Unlike fat and carbohydrate, excess protein cannot be stored and has to be excreted. Sources of ProteinCertain foods, such as meat, milk and eggs, contain all the proteins that we need. Some foods contain very little protein, such as leafy vegetables, etc. Other foods, such as cereals and legumes contain partial proteins, but eaten together provide the full complement of proteins, that is, eating cereals and legumes gives all the proteins required.
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