Protein: The Primary nutrient

by Stephen Smith BSc.

The word 'protein' comes from the Greek word, 'pro­teios', which means, 'of primary importance'. Therefore, it is imperative that an adequate amount of protein is consumed on a daily basis. Protein's importance is certainly justified considering that it is a major component of every cell and makes up over half of the dry weight of the human body. Having an adequate amount of protein in your diet is also essential if you want to achieve optimum health and peak physical condition. Your protein needs as an individual depends on a number of factors, particularly the amount and type of exercise you perform. As a general rule, the more intense you exercise or the longer you exercise for, the greater your requirement for protein is. Other conditions like age, sex, pregnancy, injury or disease may also increase your body's requirement for protein.

Sources of protein

Protein may be obtained in the diet from a number of different sources. Animal products are the best source of amino acids because they supply all of the essential amino acids. These are known as 'complete' proteins. Examples of 'complete' protein sources include foods such as red meat, chicken, fish, eggs and dairy products (soy products are also complete proteins). Combinations of 'incomplete' proteins from plants can provide all the essential amino acids as well.

The best protein source is whey protein (one of the protein sources found in dairy products). It has the highest biological value (BV) of any protein source, which means it promotes tissue repair and construction in the body. It also has the highest concentration of essential amino acids and branched chain amino acids, which have a range of beneficial effects in the body.

Chemical composition

Protein contains carbon, hydrogen, and oxygen just like fat and carbohydrate but it also has nitrogen and in some cases sulphur as well. Protein is composed of chains of amino acids and when it is consumed, enzymes in the stomach and small intestine break it down to smaller chains of amino acids or peptides (made of two or three amino acids) as well as single ('free-form') amino acids. Small peptides and 'free-form' amino acids may be absorbed through the intestinal tract into the bloodstream where they can then be used to make body proteins.