Continuing with the series of columns on basic nutrition, this week we will take a quick look at protein.  While not quite as exciting to some as the rock band of the same name, protein plays a vital role in our daily existence.  Protein is the major component of all cells in the body.  Proteins also function as enzymes, hormones, vitamins and carriers of other important molecules.  The term protein refers to a group of amino acids.  Each amino acid has been studied and found to have specific uses either by itself or in combination with other nutrients.  Some amino acids can be manufactured by our body if needed and are called “nonessential” amino acids, but others cannot be manufactured.  These amino acids are called “essential amino acids” because it is essential that we obtain them through the food that we eat.  Proteins that contain the all essential amino acids are also called “high quality” or “complete” proteins.   

Dietary sources of protein include meats, dairy products, grains and legumes.  The grain and legume foods do not contain complete proteins.  Each type of grain or bean contains different amino acids, so vegetarians must take great care in planning a diet mixed in types of beans and grains.  Animal sources of protein usually contain the high quality or complete proteins.  Most nutritionists recommend a diet with a good variety of protein sources. 

Protein deficiency is rare in the United States.  Studies indicate that the most problems with inadequate protein intake occur in those individuals with increased requirements following surgery, trauma or illness.  Vegetarians need to be very mindful of their diets and the types of protein they are eating. 

In the 21^st century, excess protein consumption seems to be more of a nutritional problem than protein deficiency in most developed countries.  Our bodies cannot store excess protein as protein.  If the amino acids are not immediately needed for body functions, protein is converted to glycogen, a temporary form of energy, and then to fat.  Proteins contain 4 calories per gram, the same as carbohydrates.  (Fats contain 9 calories per gram and alcohol contains 7 calories per gram.)  The liver removes nitrogen from the amino acids and it is incorporated into urine and excreted by the kidneys.  These organs, when healthy, can easily handle any increased workload, but when diseased, a low protein diet may be ordered by your physician.  Other problems from high intake levels of proteins may be an overreaction of the immune system.  The substances that cause many allergic reactions are protein based.  A high protein intake may also be involved with loss of bone density. 

The “meat and potatoes” concept of a good American meal has yielded a country with one of the highest intakes of protein per person.  Biologically, a human should need about .8gm/kg of good quality protein daily.  This would translate to a little less than 1 gm per 2.2 lbs of body weight.  (your ideal weight divided by 2.2 times .8)  For a quick translation into suggested ounces of meat and other good protein sources, use the tools on www.my.pyramid.gov