Information and Fact About Proteins

One of the three main classes of food. Proteins are made of amino acids, which are called the building blocks of the cells. The cells need proteins to grow and to mend themselves.

As a macronutrient, protein is the most plentiful component of the body, after water. It not only builds up body structures such as cells, tissues and skeleton, but also creates the body's functional factors, such as hormones, antibodies, DNA and digestive secretions. Protein enables children's growth, and is equally important in adulthood, when growth has ceased, to supply 'spare parts' to counteract the wear and tear of daily living. Various proteins, such as those in red blood cells, hormones and immune cells, are constantly being broken down and need to be rebuilt. Proteins also serve as a source of energy and heat, providing 4 calories per gram. Their richest dietary sources are animal foods such as eggs, meat, fish and dairy products.

Protein is made up of amino acids, in the same way that a wall is composed of bricks, and during the digestion process, it is broken down in the body to its basic 'bricks', the amino acids, which are then absorbed into the bloodstream and reassembled for new protein synthesis. Twenty-two amino acids are linked together in various forms to create the many and varied types of proteins, such as hair, bone or nails, and these processes are supervised by the nucleic acids RNA and DNA, the specific proteins that contain our genetic blueprint. Eight of these amino acids, which cannot be produced by the body and, must be supplied by food, are classified as 'essential amino acids', namely: leucine, isoleucine, valine, methionine, threonine, lysine, phenylalanine and tryptophan.

An adequate supply of dietary protein is of utmost importance in order to maintain optimal health, growth, function and rejuvenation of the body. Symptoms of protein deficiency are many and varied, ranging from hair loss, brittle nails and rough skin, to fatigue, anaemia and low sexual drive. In addition to creating protein, various amino acids, both essential and non-essential, have been found to have specific beneficial effects on health, and these amino acids are available as nutritional supplements.

Food Sources of Proteins

Food Portion Size Protein (grams)
Vegetarian Sources
Milk 1 cup 8
Cottage Cheese 1/2 cup 12
Cheddar Cheese 1 ounce 8
Yogurt 1 cup 9
Tofu (Soybean Curd) 4 ounces 8
Peanut butter 1 tablespoon 4
Pasta 1 cup 4
Rice 1 cup 4
Corn 1 cup 3
Beans 1 cup 5
Bread 1 slice 3
Chicken 3 ounces* 25
Fish 3 ounces* 21
Turkey 3 ounces* 24
Pork 3 ounces* 23
Beef 3 ounces* 25
Egg/egg white 2 Large 7

*These are general estimates, as the protein amount varies a little depending on how the meat was cooked and what part of the animal it came from (i.e. chicken breast as opposed to thigh).

For the body to use proteins with maximum efficiency, they must contain the essential amino acids, must be digestible, and must be consumed with sufficient energy from other sources (such as complex carbohydrates), so that amino acids will not be used for energy, but rather to help build and repair muscle tissue. They must also be accompanied by the vitamins and minerals needed to facilitate their use, and must be received by a healthy body able to use them.

Also see: Spirulina - A natural complete protein

Get protein supplements for your health at HealthCatalog.

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