Proteins are any of a large group of nitrogenous compounds of high molecular weight that are essential constituents of all living organisms. They consist of one or more chains of amino acids (organic compounds that are the component molecules of proteins).
Apart from water, protein is more plentiful than any other substance in the body. Constituting approx 12% of our total weight, it is responsible for growth and development within the body. Our bones, nerves and other body tissues are composed of mostly protein. Collagen, an important protein, forms the protein base of teeth, skin elasticity, the material for tendons and ligaments, and the strength in the arterial walls, and it assists in the production of scar-tissue formation. If there is an absence of energy foods (carbs & fats), protein can be used as a source of heat and energy for the body at a rate of 4 calories per gram.
Protein also performs the following functions:
* It controls the PH (acid/alkaline) level of blood and tissues.
* With the aid of some minerals, it helps regulate the body’s water balance.
* Protein in the form of enzymes helps fight bacteria, infection and disease.
* Protein is responsible for the production of milk in lactating mothers.
* It performs an important role in blood clotting.
* Transport proteins are responsible for picking up nutrients and moving them in and out of the cells. They move fat, fat soluble vitamins and minerals to every cell in the body.
* The protein, hemoglobin, carries oxygen from the lungs to the cells of organs.
The digestion time of protein foods is usually around 3 - 5 hours. During digestion, protein is broken down in to useable particles. These are the amino acids. There are 22 amino acids in a complete protein. All but 9 of these can be produced by the body, therefore, 13 amino acids are known as ‘non essential’ and 9 as ‘essential’ because they must be supplied by the diet. Some non essential amino acids can become essential in the event of stress. The body losses protein in situations of physical and emotional stress, such as surgery, emotional trauma, illness/disease or wounds. This creates extra demand on the body to consume more protein in the diet to rebuild or replace tissues that no longer function effectively. To enable the body to utilize protein properly, al amino acids must be present at the same time. If just one amino acid is missing, protein synthesis can cease altogether and all amino acids will be reduced to the proportion of the low or missing amino.
When a food contains all 22 amino acids, it is referred to as a ‘complete’ protein. If a food is low in, or missing one amino acid, it is referred to as an ‘incomplete’ protein. As a general rule, lean animal proteins are ‘complete’ proteins, while most vegetable sources are ‘incomplete’. The only method of receiving a complete protein from incomplete sources, is to combine them correctly in order to balance the content of amino acids. Soy protein is one of the only plant-derived proteins considered a complete source.
Two diseases may develop due to a protein deficiency. They are Kwashiorkor and Marasmus disease.
Kwashiorkor results from a severe protein deficiency and usually affects just-weaned children and those who are going through rapid growth phases. The body becomes swollen with fluid and a fatty liver develops.
Marasmus is basically due to starvation. A lack of protein and calories in general is involved. This disease is found in overpopulated, poor areas and where infant formulas are not adequate. In adults, protein deficiency can manifest in symptoms such as depression, lack of stamina, weakness, poor resistance to infection, and impaired healing of wounds and general recovery from disease.