Protein in the diet:
The importance of
protein
Protein is one
of the primary nutrients in the food we eat. The
main source of protein in the diet is from foods
such as meat, fish, poultry, eggs, dairy products, beans
and nuts as well as from a variety of grains, legumes, nuts,
and seeds.
Proteins provide the "building
material" for the growth and repair of tissue and are
a key part of every cell in the body.
The
word "protein" comes from a Greek root word that means "prime
or chief, first." So that gives us a good idea of the importance
of protein!
Proteins break down into substances
called amino acids. Amino acids are the building
blocks of proteins. There are 20 amino acids that the human
body needs to function.
There are two groups of amino acids -
"essential amino acids" and "non-essential
amino acids."
- Essential amino acids
are called "essential" because your body can't
make them. They need to be obtained from protein in the
diet. There are 9 essential amino acids.
- Non-essential amino acids
are called "non-essential" because it's not
essential that you get them from the protein in food -
your body is able to manufacture them from material that's
in your body. There are 11 amino acids that the body can
make with the material it has.
If you've ever heard the term "complete
protein," that refers to protein in the diet
that has all 9 essential amino acids that the body can't make
itself.
"Complete" proteins are found
in animal protein such as meat, fish, milk, and eggs. The
soybean is also a source of complete protein.
Protein from plant sources, like corn
and rice for example, is "incomplete" - simply
meaning that it doesn't have all 9 essential amino acids.
This doesn't mean that plant protein is inferior by any
means! "Complete" and "incomplete" proteins
merely refer to the number of essential amino acids in them.
What do amino acids
do?
Amino acids, the building blocks of protein, are restructured
in the body to create:
Hormones
Hormones are proteins that are produced
by living cells. Hormones circulate in body fluids, such
as the blood, and cause a certain effect on other cells
that are usually at a distance from the place where the
hormone is made.
Adrenalin
is a hormone that is produced by the body in times of
stress and adrenalin causes the heart rate and breathing
to speed up.
Enzymes
Enzymes are complex proteins formed
by plant and animal cells that assist or enable chemical
reactions in the body to occur.
Digestive enzymes,
for example, help your body break food down into chemical
particles that can be absorbed into the bloodstream.
Antibodies
An antibody is a protein produced by
certain white blood cells in response to a foreign substance,
called an antigen, such as bacteria.
Hormones, enzymes and antibodies
are just a few of the things that are ultimately made by
the body from the protein in the diet.
Daily Protein Requirements
The amount of protein you need every day
depends on various factors, including gender, age and level
of physical activity, but is roughly about 20% of your daily
nutritional needs.
Protein is seldom used for energy. That's
the job of carbohydrates and fats.
Okay! Hopefully this overview has helped
you better understand the importance of protein in the diet.
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