3.2.1.1 Protein GapFill

Proteins are organic macromolecules built from  peptidesamino acidscouscousadipose tissue, bound together into long chains.There are about 20 different amino acids which can combine to make a molecule of protein. Some of the amino acids can be built by the body from scratch – for this reason they are called 'dispensable'. If an amino acid cannot be built by the body from scratch, it is called  a misoan essentiala high biological valuean insoluble amino acid and has to be provided as a part of a healthy diet.

There are  twentyeleventwonine essential amino acids and if they are all present in a molecule of protein, such protein is called a complete protein and has a  high energy valuehigh biological valueincomplete valueinsufficient value. If one or more of the amino acids is missing, the protein is considered  a stablea solidan unstablea low biological value protein.

Protein  complementationcorrelationcomplementingcoagulation allows us to combine two or more sources of low biological value proteins to make a   textured vegetablewholefattyadequate protein. An example of this is  cheese on toasthot dogbeans on toastspaghetti bolognese. Complete proteins occur mostly in  fruits and vegetablesplant foodsanimal-derived foodsnuts, but also in  breadquinoacouscousgherkins and  olive oilsoygreen peastomatoes.

Proteins are necessary to build  all cells in the bodyunsaturated fatadipose tissuelard , enzymes and hormones. They can also be used as a  freeinsolubleprimarysecondary source of energy – this means that they are only used as a source of energy if other sources (carbohydrates and fats) are not available.
If a person eats too little protein, he or she may develop a disease called  kidney stonesscurvynight blindnesskwashiorkor. Too much protein can also be harmful for the body, causing harm to the liver and the kidneys.