• Introduction
• The Fate of Proteins
• Nutritional Requirements
• Chart of Essential Amino Acid Sources  

Introduction:

     Proteins are small molecules composed of approximately 22 different amino acids strung together.   Due to specific interactions between amino acids, a 3 dimensional structure is attained rendering the protein capable of acting as an enzyme or to giving it the ability to form the architecture of our bodies.   In both plants and animals proteins play a plethora of vital roles, without which we could not survive.   At the simplest level, proteins can be broken down and used as a source of energy.   Alternatively it can be used as an enzyme designed to perform specific tasks such as hormone regulation or regulation of internal biochemical reactions.   Lastly, proteins serve as a means by which each cell can create its own unique architecture.    Proteins play so many roles that they could not be realistically represented here.

What Happens to Proteins After They are Ingested?

     Ingested proteins are broken down in the stomach and small intestine by enzymes (also proteins) which chop up them up into smaller building blocks called amino acids.   Once taken up into the cell, the amino acids are then converted into new proteins required by the cell.   Its worth mentioning that in order for a protein to be properly assembled by the cell, amino acids must be present in similar ratios as those found in the human body.   The only really good way to do that is to consume foods from a variety of protein sources.   Milk and eggs are excellent sources of protein as they have ratios comparable to those found in man.  An important consideration for individuals on vegetarian diets is that plants tend to have a protein composition slightly different from what is typically found in man.   More attention must be paid in making sure that the full complement of amino acids are attained, otherwise a gradual wasting away of muscle and body mass may begin (see starvation).

Nutritional Requirements for Essential Amino acids

     Many amino acids are made by the body itself provided that sufficient levels of protein exist.   There are eight, however, which cannot be made by us.   These are referred to as “essential amino acids” and must be obtained from the foods we eat.

  Charts Containing the protein composition of many classes of common foods.

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