What is Protein and How is it Important?
By Matthew Johnson
Protein is one of the most important substances we consume. After
this article you will know how much protein your body needs. The
function it plays in survival, the way it is processed and used.
Other than water, protein is the most abundant nutrient in the body.
Protein is a chain of linked units called amino acids. The protein you eat is split apart into these amino acids, absorbed in the small intestines, then rearranged and put back in the blood stream.
These new arranged proteins carry out specific functions to maintain life.
All living tissues are made up of twenty-two essential and nonessential amino acids.
Essential amino acids are not made by the body and must be supplied through diet.
There are nine essential amino acids: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and
Valine. The remaining thirteen are nonessential amino acids produced in the body and not essential to consume through the diet.
Protein provides four calories per gram. The human body can do three
things with protein calories; put protein in fat stores, use it
as an energy source or use it to carry out functions vital to life.
Protein calories will be used as an energy source when the body
is lacking fat or carbohydrate calories for fuel. When the body
receives sufficient quantities of proteins, fats and carbohydrates,
protein will carry out its specific functions. These proteins functions
include: replacement of old cells, building muscles, organs, blood,
nails, hair, skin, and tissues. Protein also takes part in hormone,
antibodies, and enzyme formation.
Fasting your body without proper protein intake will cause your
body to slowly start shutting down. You must not only eat enough
protein, but you must eat the right types. Without the right amount
of essential proteins, no matter how much you eat, your body will
waste the protein and not run properly.
A diet that is low in essential amino acids does not carry out all of its protein functions.
Protein follows the all-or-none law: inadequate amounts of essential amino acids cause the body to excrete proteins in urine as urea.
The remainder of the protein is converted to glucose, fat, or metabolized for energy.
This lack of essential amino acids prevents proteins from performing their normal functions.
Foods that have all nine of the essential amino acids are called complete proteins. Complete proteins include all food from animal products, milk, cheese, chicken, beef, and ext.
Don't worry folks! Proteins that are incomplete (plant products) can be combined with complementary proteins that carry the missing amino acids to form a complete protein.
Examples of incomplete protein are grains, cereals, and vegetables.
To complement these proteins you would combine beans with grains, or nuts with cereal.
Now that you have an understanding of the right kinds of protein to eat, we will discuss how many grams you need to eat.
In Understanding Normal and Clinical Nutrition, the Authors say, "The Committee on Dietary Allowances of the Food Nutrition Board of the National Academy of Sciences states the RDA in grams of protein per kilogram of body weight per
day" (Whitney 153). If calories are sufficient in carbohydrates and fat, You divide your body weight by 2.2, this gives your weight in kilograms. You multiply your kilogram weight by 0.8, this gives you your daily intake of protein. A person who weighs 95 kilograms (210 pounds), would take 95 kilograms times 0.8. Their daily protein intake would work out to be around 77 grams, 12% of your calories would come from protein.
We do know that long bouts of exercising increases the need for nutrients, especially protein. In Nutrition For Fitness and Sport the author says, " a number of studies involving endurance athletes found that 0.97-1.37 grams of protein per kilogram per day were needed" (Williams 112).
Click here for our free tool that calculates protein requirements:
daily
protein requirements
 |
Matthew Johnson is a personal trainer
and an on-line fitness consultant at Changing Shape. |
References
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Whitney, Eleanor Noss., III, et al, Understanding Normal and Clinical
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Williams, Melvin H., Nutrition for Fitness and Sport, William C.
Brown Company Publishers, Iowa: 1983. |
