Dietary Proteins
Introduction
Proteins are essential for our body. To be healthy, we have to eat the right amount and
the right kind of protein. The protein we take from food sources is known as dietary
protein.
It is possible to eat plenty of protein and still not get the
right kind of protein our body needs. That is why it is
important to understand the healthy choices for dietary
protein.
This reference summary defines proteins and explains
where to find good sources of proteins. It discusses
essential amino acids foods that have complete amino
acids, and how to combine different protein sources to get the dietary protein the body
needs. Two special sections give tips for vegetarians and for healthy eating.
Role of Proteins in the Body
Proteins are very important to our body. They are needed to build
big, supporting structures like bone and muscle as well as the small,
functioning structures that make every cell work.
On the outside of the body, hair, the outer layer of the skin and nail
are all made of proteins. One such protein is keratin. On the inside
of the body, muscle fibers contain several types of proteins. Bone
has lots of proteins too.
Within red blood cells, hemoglobin, which carries oxygen to every
cell in the body, has the protein globin. Enzymes, which are
important for digestion and chemical reactions inside the body, are
proteins. Neurotransmitters, which make nerve cells and the brain
work, require protein. And the list goes on and on.
The body requires relatively more protein as it grows or after an injury or surgery.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
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Last reviewed: 02/02/2017
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Protein and Amino Acids
We get the protein our body needs from plant and animal based food. The body can
also make some of the protein it needs. When we eat foods containing protein, the
body breaks them down during digestion. Proteins are constantly being broken down
and rebuilt by the body. This is because proteins are made up of amino acids.
Amino acids are known as the building blocks of
protein. There are 22 major amino acids. Imagine
each one as a block with a letter of the alphabet.
The different proteins of the body are like long
chains of words and sentences made from the
building block letters!
Amino Acids
The cells in the digestive tract cannot let big
chains of amino acids pass through. They must
first break them into single amino acids or pairs of
amino acids. Only then can they be absorbed by
the body. After they are absorbed by the body, the amino acids are used to make the
large chains of proteins your body needs.
The body recycles many of the proteins within it. It uses more amino acids from dying
cells than from the food we eat. The body can also make 13 of the 22 amino acids. We
do not need to rely on food to get these 13 amino acids. But we do need to eat a
healthy diet rich in protein to get the 9 amino acids that the body cannot make. The 9
amino acids the body cannot make are known as essential amino acids. Lysine is one
example of an essential amino acid.
If a person’s diet does not contain sufficient amounts of proteins, the body starts
breaking down the muscle proteins to use them elsewhere. That is why many people
with anorexia have little muscle mass.
Anorexia nervosa is an eating disorder that makes people lose more weight than is
considered healthy for their age and height. People with anorexia may have an intense
fear of weight gain, even when they are underweight. They may excessively diet or
exercise, or use other methods to lose weight.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/02/2017
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Daily Needs
For a healthy diet, we need to look at the amount of protein
we consume each day as well as its quality. For instance,
eating a lot of only one source of protein may not get you all
the amino acids your body needs. The amount of protein you
need each day depends on your age and gender. More
protein is needed as we grow older. Also, men need more
protein than women.
Children from ages 1 to 3 should get 13 grams of protein
each day. Children 4 to 8 years old should get 19 grams.
Children 9 to 13 years old should take in 34 grams of protein
each day. Three ounces of red meat has about 25 grams of
protein.
Females 14 and older should take in 46 grams of protein each day. Boys 14 to 18
years old need 52 grams while men 19 and older should get 56 grams of protein daily.
Half a chicken or 130 grams of chicken breast has about 40 grams of protein.
Most people have no trouble getting the right amount of protein in their diet. In fact,
most people take in more protein than they need. Taking in more protein than you
need is usually not harmful. But people with kidney or liver diseases should be careful
about how much protein they take in. Eating a low-protein diet may help people with
kidney diseases.
Talk to your health care provider about how
much dietary protein you should take in if you
have a kidney or liver disease.
Dietary proteins that have many of the 9
essential amino acids are known as complete
proteins. Those that do not contain enough of
the essential amino acids are called incomplete
proteins. For example, beans are rich in protein
but do not have all 9 essential amino acids. But soybeans are rich in protein and
contain all of the essential amino acids. Although beans do not have all of the essential
amino acids, if they are eaten with brown rice, the combined food contains all of the
essential amino acids.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/02/2017
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Remember how amino acids are like building-block letters and the proteins are words
and sentences? Imagine writing a sentence without being able to use the letter a or b!
You need all the letters to be able to write! Similarly, the body needs all the amino
acids in order to make the enzymes and structures necessary for the body.
The following are 3 examples of incomplete proteins made complete by combining
them with another incomplete source of dietary protein:
• Cheese is incomplete but made complete when added to a whole-grain
sandwich.
• Lentils are incomplete but made complete in a dish that contains nuts or seeds.
• Beans are incomplete but made complete by adding cheese.
Protein and Food Sources
Some good dietary sources of protein are animal based
foods and soy. With the exception of soy, most plant
sources do not provide as many essential amino acids
as animal sources. But with a balanced diet, it is
possible to get all the proteins and amino acids your
body needs from plant based food.
Animal based products include meat, fish, milk and eggs. These are the most complete
sources of protein and contain many different essential amino acids. Soy is a unique
plant source of dietary protein because it is complete and includes many of the
essential amino acids.
Other plant based sources such as peas, beans, nuts and
seeds are rich in protein but should be balanced. They
should be eaten with other sources of protein in order to get
all the essential amino acids. This is as simple as using
whole grain brown rice or adding cheese to the meal.
Vegetarians & Protein
Vegetarians do not eat meat and vegans do not eat any food from animal sources.
Plant sources don’t have as many essential amino acids as animal sources. People
who do not eat animal sources need to eat a variety of legumes rich in protein to get all
the essential amino acids. Legumes are plants like soybeans, black beans and lentils,
etc.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/02/2017
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It is important for vegetarians to get protein every day. They
do not have to make every meal a protein rich meal. But they
should eat the total recommended amount of protein per
day.
Soybeans are a great source of protein for vegetarians and
non-vegetarians. They are abundant in proteins and have all
of the essential amino acids. One cup of soybeans has more
protein than 3 oz of red meat. It is also healthier since it has
no cholesterol, little fat and lots of fiber.
Healthy Eating & Proteins
Though animal based foods are a great source of protein, this option comes with some
risks if you don’t make healthy choices. Meat and eggs are very rich in cholesterol.
Cholesterol causes narrowing of the arteries over time. This leads to heart attacks and
strokes that are often fatal.
Animal based foods rich in protein, such as red meat and
dairy products, are often high in fat. Eating too many of
these sources can raise your risk of heart disease.
Eating animal based foods in large portions means that
you are also taking in more calories. If you take in more
calories than you use throughout the day, you will gain
weight. Being overweight raises the risk for many
diseases, including heart disease and diabetes.
Remember these tips for healthy eating:
1. Choose lean or low-fat meat and poultry. For instance, chicken breast meat, or
white meat, has less fat than chicken leg meat, or dark meat.
2. Avoid solid animal fat. Examples of unhealthy choices are frying chicken in
shortening or frying eggs in butter or stick margarine.
3. Select some seafood that is rich in the vitamin omega-3 fatty acids, such as
salmon, trout, sardines, anchovies, herring, Pacific oysters, and Atlantic and
Pacific mackerel.
4. Avoid processed meats which have added sodium. This includes ham, sausage,
frankfurters, and luncheon or deli meats.
5. Check the Nutrition Facts label to help make healthy choices.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/02/2017
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Summary
Proteins are in every living cell in the body. Our bodies need protein from the foods we
eat to build and maintain bones, muscles and skin. Proteins are made of smaller
building blocks called amino acids. There are 22 main amino acids.
We get proteins in our diet from meat, dairy products, nuts and certain grains and
beans. Proteins from meat and other animal based foods are complete proteins. This
means they supply all of the amino acids the body can't make on its own.
Plant proteins are incomplete. You must combine them to get all of the amino acids
your body needs. Soybeans are an exception as they contain most of the essential
amino acids our body needs.
It is important to get enough dietary protein. You need to eat protein every day
because your body doesn't store it the way it stores fats or carbohydrates.
The average person needs 50 to 65 grams of
protein each day. This is the amount in four
ounces of meat plus a cup of cottage cheese.
Animal based foods and soybeans are good
sources of essential amino acids. Soy is the
only plant source that contains all of the
essential amino acids. For this reason,
vegetarians may need to be more aware of
their protein intake than people that eat meat.
Animal based food is a great source of
protein, but it comes with some risks if you
don’t make healthy choices. Animal based
food is high in cholesterol and other potentially harmful fats.
This document is for informational purposes and is not intended to be a substitute for the advice of a doctor or healthcare professional or a
recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the
advice of a doctor or a healthcare professional for your specific condition.
©1995-2017, The Patient Education Institute, Inc. www.X-Plain.com
Last reviewed: 02/02/2017
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