Protein is widely regarded as the most important nutrient, and the average American not wanting to stint on a good thing than he really needs.unfortunately , while packing in protein, most people consume too much fat and possibly too many calories , winch are the “baggage” in most high protein food, thus , instead of being good to their bodies, they may actually do themselves a disservice.
At the same time , many don’t realize that the vegetables they commonly think of as starchy (that is , laden with carbohydrates) can actually be good sources of protein , minus the artery clogging fats and cholesterol that are in most animal protein foods.others who spurn animal proteins whether for religious, moral or health reasons – and instead rely on vegetable protein, may not consume adequate amounts of usable protein because they don’t understand the precise demands of the body’s protein requirements.
The myths and misconceptions about protein date back 150 years when a dutch chemist coined the name protein from a Greek word meaning “to take first place”. perhaps the chemist was acknowledging the primacy of protein’s main functions – to maintain body tissues and support growth – and the fact that the body can only make protein from proteins supplied in the diet,whereas fats and carbohydrates can be derived from one another and from protein as well.

But thinking of protein as the “first place” nutrient overlooks the nutritional value of the fats and carbohydrates and than protein, must provide the bulk of calories in a healthy diet.In fact , if the diet doesn’t contain adequate calories from carbohydrates and fats, the body is forced to use protein for energy instead for building or repairing body tissues.
The main nutrition problem in most developing countries rather than a protein shortage.If more carbohydrates or fat calories where available , in most cases the diets in these countries would contain adequate protein to support normal growth and development.
Proteins are made up of chains of building blocks called amino acids, molecules that contain nitrogen. sometimes as many as 200 amino acid molecules are strung together to make one protein.
There are about 20 different amino acids in nature, and the human body is able to manufacture all but eight and possibly nine of them from carbohydrates and nitrogen, usually derived from dietary proteins.These eight or nine are called essential amino acids;they all must be supplied as such in the diet for body to be able to manufacture the hundreds if different proteins it needs.

All protein originally comes from plants,which unlike animals can incorporate inorganic nitrogen from the air and soil into organics compounds (amino acids) that can be used by man and other animals. but there are important differences between animal and plant 9vegetable) proteins in terms of their amino acid constituents. Animal protein contains all the amino acids essential to man, whereas different vegetable proteins may be deficient in one or another essential acid.
The protein you eat is broken down, or digested, into it’s constituent amino acids, which are absorbed into the blood stream and distributed to cells, where they can be taken apart and reassembled into new proteins according to the needs of the cells.
every cell in your body contains some protein.Protein comprises 50 percent of the body’s dry weight.
Muscle ,bone, cartilage, skin, blood, lymph all contain protein.
All enzymes and many hormones are proteins. only bile and urine normally lack protein.
Protein in muscle allows it to contract and hold water.In hair, skin and nails, the protein is hard and insoluble, giving a body a protective coating .protein elasticizes blood vessel walls, allowing them to expand and contract to maintain normal blood pressure. and protein provides the rigid framework for the minerals of bones and teeth.
Without protein, new tissues needed for growth cannot be formed and old worj out tissues cannot be replaced. Proteins are also involved in regulating the body’s water and acid base balance and stimulating the production of antibody.

Factors that affect the body’s ability to use protein in the diet for these purposes include the following
whether the diet contains sufficient calories to fulfill the body’s energy needs.If calories are inadequate the body will use protein in the diet for fuel rather than for tissue building .

The frequency with which protein is supplied in the diet. the body doesn’t store protein the way it stores extra fat in fat cells or extra carbohydrates in the liver and muscles. protein must be consumed daily, preferably at each meal.In fact, the body uses protein most efficiently if it is consumed in frequent small meals – For example , six a day than if eaten at three big meals.

Whether the protein consumed is balanced to supply adequate amounts of essential amino acids plus a healthy supply of nonessential ones.because protein is not stores , all the amino acids needed to make new protein must be supplied at the same meal. If the protein you eat is from animals (for example , meat, milk products, fish , poultry or eggs), it will be balanced enough to assure efficient utilization.
An exception is gelatin, which is missing two essential amino acids.If eaten alone (say as a bedtime snack), the protein in gelatin can only be used for energy, not to make new protein.
A vegetable protein source that is nearly as well balanced as animal protein is soybeans. However, most vegetable proteins contain inadequate amounts of one or more essential amino acids to suffice by themselves as protein sources. For the body to use these vegetables and gelatin to make new protein, several different ones called complementary proteins must be combined in the same meal or they must be eaten with animal protein so that the amino acid deficiencies in the vegetable are made up for by the other foods eaten.
For example , the Mexicans eat tortillas ( corn bread, which is low in the essential amino acid lysine) with beans (which have plenty of lysine but are short on another essential amino acid , methionine) and thereby derive a balanced protein. A peanut butter sandwich on whole wheat bread is also balanced protein.Some other examples are rice and beans, macaroni and cheese, cereal and milk, rice or bulger with meat, fish or poultry.

When supplementing a vegetable protein with animal protein, only a very small amount of the animal protein is needed to provide the complementary amino acids for the vegetable protein. In many Asian cultures, for example , rice is the main course of protein, with meat or poultry used as a condiment to balance out the vegetable protein.
Other factors that effects the body’s use of protein include inactivity, injury,illness and emotional stress, all of which lead to an excessive loss of nitrogen in the urine , indicating that protein in body tissues is being excreted.
In general, the amount of protein your body needs is mainly determined by your age and size. per pound of body weight, the need is greatest during the first six months of life and except for women who are pregnant or breast feeding and need extra protein, the protein requirement declines slowly with age.
The food and nutrition board of the national research council has prepared a list of recommended dietary allowances (rdas) for protein , which represents the minimum protein required per day at different ages plus a substantial safety factor of about 45 percent.This would meet the needs of nearly all healthy persons.
However, the average American eats twice the recommend amounts, with the extra protein simply being a source of calories (four calories a gram), not protein for the body .this is why you can get fat eating excess protein. It is generally recommended that a third of the needed protein should come from animal sources and the rest from vegetables, but in this country 60 to 80 percent of the protein eaten is animal protein.

According to the rdas, an eight year old child weighting 60 pounds needs a same amount of protein each day about 60 grams as a 130 pound adult women. A 150 pound adult whose rda for protein is about 54 grams a day, could satisfy that need by eating.