Proteins are
compounds composed of atoms of carbon, hydrogen, oxygen, nitrogen,
and sometimes sulfur, arranged as strands of amino acids. Protein is
part of every cell and no new living tissue can be built without
protein. Approximately 20% of a person's total body weight is
protein. One gram of protein provides 4 calories.
There are many forms
of proteins, including enzymes, antibodies, hormones, transport
vehicles, oxygen carriers, tendons and ligaments, scars, the cores of
bones and teeth, the filaments of hair, the materials of nails, and
more! Proteins help regulate fluid balance and the acid-base balance.
The roles of protein in the body are more varied than those of
carbohydrates or fat.
Our bodies cannot
store amino acids for future use which is why it is important that we
consume essential amino acids daily. Essential amino acids are amino
acids that the body cannot make for itself, or it doesn't make enough
of them to be useful. When we consume protein, our bodies break it
down into individual amino acids, absorb them into the bloodstream,
then they are taken up by various cells in the body.
Complete proteins
are proteins that contain all of the essential amino acids in the
right proportion relative to need. Protein quality is a measure of
the essential amino acid content of a protein relative to the needs
of the body. Egg-white protein is the standard to which other
proteins are compared to determine protein quality, this is called
the reference protein. Egg-white protein has a score of 100.
Generally, amino
acids from animal and soy proteins are the most easily absorbed. Our
bodies can absorb 90-100% of the amino acids from animal and soy
proteins. Legumes are the next best, with an 80-90% absorption rate.
Amino acids from grains and other plant sources are absorbed at a
rate of 70-90%. I recommend getting your protein content from animal
and soy sources. Soybeans are the only plant source that contains
complete protein, meaning they supply all of the essential amino
acids needed for good health.
Good sources of
protein include meat, poultry, fish, shellfish, tofu, tempeh,
legumes, nuts, seeds, eggs, peanut butter, milk, cheese, cottage
cheese, greek yogurt, and of course, protein shakes. I have a protein
shake almost daily for weight management, but I also eat a variety of
protein sources.
The
protein deficiency disease, kwashiorkor, is
defined as a lack of protein while there is still adequate food
energy. This is very rare in the United States. Those
who suffer from kwashiorkor have a lack of skin and hair pigment,
poor wound healing, deteriorating digestive tract, and they develop
edema. Edema is swelling of the body's tissues due to fluid
leakage from blood vessels.
Determining how much
protein to consume each day can be done in two ways. The first is by
a simple calculation that involves your desirable weight. Use a BMI
chart to determine your desirable weight (do not use your actual
weight). Divide that number by 2.2. (Pounds divided by 2.2 =
kilograms.) Then multiply by 0.8 to determine grams of protein needed
each day.
Here is my
personal calculation:
120 pounds / 2.2
= 55 kilograms (round up!)
55 kilograms x
0.80 = 44 grams of protein
Based on that
calculation, I need at least 44 grams of protein each day.
The second way to
determine how much protein to consume is by a calculation that
involves your caloric intake. It is recommended that protein intake
be 10-35% of your total calories.
Here is my
personal calculation:
1500 calories x
0.10 = 150 calories / 4 calories per gram of protein = 37.5 grams of
protein
1500 calories x
0.35 = 525 calories / 4 calories per gram of protein = 131.25 grams
of protein
Based on those
calculations, I need between 37.5-131.25 grams of protein each day.
My
personal goal for protein is 25% of my caloric intake, which is 93.75
grams of protein each day.
These
recommendations are for average adults, not for endurance athletes or
resistance training athletes. I will discuss protein needs for
athletes
in a future post!
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