Download Nutrition Essentials: Protein

Nutrition Essentials: Protein
Welcome
Slide 1
Welcome to Nutrition Essentials, a Texas A&M AgriLife Extension Service Professional
Development Training Program. Nutrition Essentials cover seven basic relevant nutrition topics:
Overview, Carbohydrates, Protein, Fat, Vitamins, Minerals, and Beverages. Each module is
approximately one hour in length.
This course will be presented in a voice-narrated format that allows you to follow along with a
PowerPoint slide presentation. A high-speed Internet connection is required to complete
Nutrition Essentials. Content for this module, Nutrition Essentials: Protein, is divided into
multiple sections (see menu bar on the left for course outline), enabling you to complete
and/or review content at your own pace. Printable handouts, if applicable, will be presented
prior to the section in which they are referenced.
In the next section, you will be directed to complete a brief, multiple-choice pre-learning
assessment. Once you have completed the pre-learning assessment, you will be free to advance
to the course content by clicking on the “Next Section” button at the bottom of the page. At the
conclusion of this module, you will be directed to complete a post-learning assessment that will
determine if you successfully pass the course.
If at any time you wish to take a break from the module, simply log out and return to the course
when you are ready to continue. When you sign back in to the module, you will be taken
directly to the section where you left off. To review a section you have already completed, click
on the desired section on the left menu bar.
Introduction and Learning Objectives
Slide 2
This is the third module in the Nutrition Essentials series of online lessons, and it provides an
overview of protein, an essential nutrient. Other modules in this series include Overview,
Carbohydrates, Fat, Vitamins, Minerals, and Beverages. Because the modules build on one
another, they’re best when reviewed in this sequence.
At the conclusion of this module, participants will be able to:

Discuss the functions of protein;

Explain the difference between essential and non-essential amino acids;

Estimate individual protein needs;

Identify protein foods that reflect the recommendations by the Dietary Guidelines for
Americans;

Discuss protein foods that are suitable for vegetarians;

Describe how protein is digested and absorbed by the body; and

List three claims that are often made by companies that market protein and amino acid
supplements.
Slide 3
During this module, we’ll learn about protein and its role in the diet. We’ll discuss the benefits
of protein and learn the difference between essential and non-essential amino acids. We’ll also
discuss current dietary recommendations for protein and the recommended foods to meet
those needs. We’ll briefly review protein digestion and absorption, learn how protein can help
with weight management, and end the module with a discussion on protein supplements.
Definition and Benefits of Protein
Slide 4
Protein is a nutrient that is comprised of amino acids. Sometimes these amino acids are
referred to as building blocks for protein. Each amino acid has the same basic structure and
includes carbon, hydrogen, oxygen, nitrogen, and a unique side group. The side group is
different on each amino acid and helps to distinguish one amino acid from another.
Slide 5
Protein is often associated with helping the body build muscle and other tissues, but as you can
see, this nutrient does much more. The body uses protein to make enzymes and hormones.
Enzymes help facilitate the many chemical reactions that occur in the body every day.
Hormones are often thought of as chemical messengers that travel to targeted tissues and
cause a specific response. Protein is also used to help the body maintain fluid balance. That
means making sure that the body has the right types of fluids in the right amounts.
Another important function of protein is acid-base balance. Numerous chemical reactions
happen in the body every day. As a result of these reactions, acids and bases are produced and
carried by the blood to the kidneys and lungs so they can be eliminated. To keep the blood at
the right pH, the body uses protein to buffer the acids and bases.
Protein also serves as a transporter, carrying nutrients and other molecules throughout the
body. For example, hemoglobin is a protein that carries oxygen from the lungs throughout the
rest of the body.
Protein is also used to make antibodies, which help fight infections. Additionally, protein can be
used as a source of energy, if needed.
Classification of Amino Acids
Slide 6
Every day, the body uses amino acids to build proteins. However, for those proteins to be built,
all of the necessary amino acids need to be present.
Our body uses 20 different amino acids to make protein. These amino acids can be classified as
either essential or non-essential.
Non-essential amino acids are those that can be made by the body from nitrogen and
carbohydrate or fat. Most of the amino acids that the body uses are non-essential.
Essential amino acids are those that cannot be made at all by the body or made in sufficient
amounts that the body needs. These essential amino acids must be obtained from the diet.
Slide 7
Generally speaking, 9 of the 20 amino acids used by the body are considered to be essential.
This means they must be obtained through the diet because the body either cannot make them
or it cannot make them in sufficient amounts. The amino acids listed in the first column are
those that are considered essential. The non-essential amino acids are shown in the second
column.
What Foods Contain Protein?
Slide 8
Given the many roles that protein plays in the body, it’s important to consume proteincontaining foods every day. This will assure that the body receives the required essential amino
acids, as well as the nitrogen needed to make the non-essential amino acids.
A variety of foods contain protein, including meat and eggs, nuts and seeds, processed soy
products, and beans and peas.
Slide 9
As we learned earlier, essential amino acids are those that must be obtained from the diet.
Foods with the highest amount of essential amino acids per serving include meat, fish, poultry,
eggs, and soy products.
Fruits, vegetables, breads, and other grain foods have lower amounts of essential amino acids.
Slide 10
It’s important to choose high-quality protein foods to assure that your body gets the essential
amino acids it needs. Protein foods that come from animal sources, like eggs and meat, have all
the essential amino acids needed by the body. These foods are often called complete proteins.
With the exception of soy, protein foods that come from plant sources often lack one or more
essential amino acids. These foods are often called incomplete proteins. For those individuals
who only eat a plant-based diet, it’s important that they eat a variety of protein foods from
vegetable sources to make sure they get the necessary essential amino acids.
Soy is the only plant-based protein food that is a complete protein.
Slide 11
Milk, yogurt, and cheese are considered complete proteins because they contain the needed
essential amino acids. However, since these foods contribute significantly to the calcium intake
in the United States, the Dietary Guidelines for Americans groups them and other dairy foods
separately.
Individuals who consume dairy foods in addition to foods rich in protein should have no
problem meeting or even exceeding their protein requirements.
Estimating Protein Needs
Slide 12
Protein needs are often based on age and body weight, but other factors, including illness and
injury, can increase protein needs.
As shown in this chart, children need more grams of protein per kilogram of body weight than
adults. That’s because more protein is needed at this younger age to support the growth and
development of new tissue. By adulthood, protein needs decrease because we’re no longer
growing. Instead, during adulthood, protein supports the maintenance and repair of body
tissue.
Slide 13
Here’s an example of how protein needs are calculated.
An adult needs 0.8 grams of protein for every kilogram of body weight. First, you need to
convert a person’s weight in pounds into kilograms. Because there are 2.2 pounds in 1
kilogram, dividing one’s weight in pounds by 2.2 will give you the total number of kilograms.
After you calculate an adult’s weight in kilograms, multiply that number by 0.8 to arrive at the
estimated grams of protein needed for a healthy adult.
Here’s an example: Fran is a 54-year-old female who weighs 132 pounds. 132 pounds is equal
to about 60 kilograms. When weight in kilograms is multiplied by 0.8, we see that Fran needs 48
grams of protein based on her weight.
Keep in mind that this is just an estimate. If Fran had other health issues, her protein needs
could be different.
Slide 14
An easier way to determine a person’s protein needs is by using the SuperTracker website
developed by the United States Department of Agriculture. This website allows you to estimate
your calorie and nutrient needs, including protein.
To visit the website, go to https://www.supertracker.usda.gov/default.aspx.
On this website, you can create a profile by entering your age, gender, height, weight, and
physical activity habits. You’ll get a customized plan that’s complete with your estimated calorie
needs and the recommended amounts of food from the different food groups that are needed
to promote good health. Track your progress towards meeting your food goals by entering in
your food intake and physical activity each day.
Dietary Guidelines for Protein
Slide 15
The Dietary Guidelines for Americans encourage us to eat a variety of protein foods that reflect
our energy and nutrient requirements. Specifically, it’s recommended that one choose a variety
of protein foods, such as low-fat meats, poultry, fish, seafood, eggs, legumes, and nuts and
seeds.
Slide 16
Because seafood has beneficial fats that may help prevent heart disease, experts recommend
that individuals should try to include as much as 8 ounces of seafood in the diet each week. This
is roughly 20% of our total protein intake.
To get the greatest health benefits from seafood, choose seafood that is high in omega-3 fatty
acids and low in methyl mercury. This includes salmon, trout, and herring.
To learn more about the health benefits of fish, visit www.Fish4Health.net.
Slide 17
Some people may wonder if it’s possible to meet their protein requirements if they are
vegetarian. The answer is “yes,” but depending on the type of vegetarian diet one is following,
it may require a little extra planning.
Slide 18
Generally speaking, there are four different types of vegetarians. All vegetarians consume
fruits, vegetables, grains, nuts, and seeds. A vegan is one who doesn’t eat any food that comes
from an animal. This includes not only meat, fish, and poultry but also eggs, milk, and cheese.
A lacto-vegetarian consumes foods made from dairy products. This includes milk, cheese, and
yogurt.
An ovo-vegetarian consumes eggs but no other animal foods.
A lacto-ovo vegetarian consumes dairy and eggs but not any other meat, fish, or seafood.
To learn more about vegetarian diets, visit the Academy of Nutrition and Dietetics at
http://www.eatright.org.
Slide 19
All vegetarians can consume beans, peas, soy foods, nuts, and seeds to help meet their protein
needs. Keep in mind that the amount of protein foods for vegetarians is similar to that of nonvegetarians. Protein supplements aren’t necessary for vegetarians IF meals and snacks are
carefully planned.
Vegans, or those who eat no animal-based foods, may benefit from supplements or fortified
foods to assure that calcium and B12 needs are met.
Slide 20
This chart illustrates the average amount of protein foods required for a 2,000 calorie diet. Both
vegetarian and non-vegetarian examples are given. All three diets shown, which include both
vegetarian and non-vegetarian, meet the protein requirements; however, they’re different in
the types of protein foods that are emphasized.
Protein Digestion and Absorption
Slide 21
Earlier, we learned that a protein is made up of a large chain or even many chains of amino
acids. Before our body can use the protein found in foods, it has to be digested and absorbed.
Protein digestion involves breaking down those chains of amino acids into individual amino
acids, which are ultimately absorbed by the body.
Slide 22
Protein digestion begins in the mouth where food is chewed and moistened with saliva. After
the food is swallowed, acid in the stomach begins to uncoil the chains of amino acids. An
enzyme called pepsin is activated and begins to break the chains of amino acids into smaller
chains called polypeptides. Polypeptides are smaller proteins made up of shorter chains of
amino acids.
Polypeptides then move into the small intestine and are broken down into shorter amino acid
chains with help from pancreatic and intestinal enzymes. Then, enzymes that are located in the
wall of the small intestine break down the last of the amino acid chains into single amino acids.
Slide 23
After digestion, the amino acids are absorbed by the cells that line the wall of the small
intestine. The amino acids travel in the bloodstream to where they’re needed in the body. The
body can use the amino acids for energy, make non-essential amino acids or other proteins,
make other compounds such as hormones or enzymes, or use them to make glucose or fat.
Protein and Health
Slide 24
Most people in the United States get more than enough protein, which is needed for good
health. However, there are certain times in one’s life when additional protein is needed, such as
during periods of growth, pregnancy, lactation, or recovery from an illness.
High-protein diets are often promoted for various health reasons, but in reality, there are some
groups of people who shouldn’t consume protein in excess. These groups include those with
liver or kidney disease. In addition, excessive protein intake can result in a diet that’s too high in
total fat, saturated fat, and cholesterol. Individuals who need to increase their protein intake
should do it by choosing lean protein foods.
Slide 25
Research continues to show that protein plays an important role in promoting a healthy weight.
For example, studies show that having high-quality protein in the diet can help promote satiety,
which is a feeling of fullness. This, in turn, can help to reduce hunger and help people eat less.
Additionally, adding a little more protein in the diet when trying to lose weight can help spare
muscle loss. This is as simple as adding some low-fat protein with each meal.
Slide 26
Individuals who want to add some extra protein to their diets may be tempted to turn to
dietary supplements. These supplements are available in stores and marketed heavily in the
media and on the Internet. Protein supplements are often marketed with claims that they will
help with weight loss, help improve athletic performance, or even help fingernails grow. Amino
acid supplements are marketed and sold to people in the hopes of preventing cold sores or
getting a better night’s sleep.
Slide 27
Unfortunately, research doesn’t confirm most of the claims made by the marketers of protein
and amino acid supplements. Most people who need extra protein can obtain it by adding
nutrient-dense protein foods in their diet. Supplements of single amino acids aren’t
recommended as there is no research to support their proposed benefits. In addition, taking
supplements of individual amino acids could lead to excessive intake.
Finally, dietary supplements of protein or amino acid can be very expensive when compared to
food!
Slide 28
Here you see two foods that contain protein, along with a protein supplement. Suppose you’re
trying to add extra protein to your diet and want to do so in a way that doesn’t cost too much
or add too many calories.
The first food is a can of tuna packed in water. The three-ounce can costs $1.29 and provides 26
grams of protein and 120 calories. In addition to the protein, the tuna also provides small
amounts of vitamin A, calcium, and iron.
Next, we have a protein bar. This is a specially made bar that is fortified with protein and other
nutrients. At $1.58, this protein bar provides 30 grams of protein and is a good source of
calcium and iron – all for 360 calories.
Last, we have a protein supplement. Two scoops of this powdered supplement costs $1.59, and
it’s mixed with water to provide 40 grams of protein and more than half of the daily value for
vitamin A, vitamin C, calcium, and iron. In addition, the supplement provides 280 calories.
At first glance, you might choose the protein powder because it provides the most protein.
However, you’ll also be adding almost 300 calories to your diet. To avoid weight gain, you’ll
need to either decrease calories somewhere else in your diet or increase your physical activity.
Also, ask yourself this question: “Do I need those additional nutrients?”
The bar looks good, but it doesn’t provide as much protein as the supplement, and it
contributes 360 extra calories. That’s quite a bit for what looks to be a small snack.
The tuna provides the least amount of protein per serving, but it also has the least amount of
calories.
All three products are similar with respect to cost.
So, if you were trying to increase your protein intake, which one would you choose? If you’re
watching your calories, then the can of tuna is a great way to boost your protein intake without
adding too many calories to your plate. It’s also low in fat and saturated fat. If calories aren’t a
concern, then perhaps the protein supplement is a good option since it’s not only high in
protein but also low in fat. The bar is a good source of protein, but it’s high in fat. In addition,
more than a third of the fat in the protein bar is from saturated fat.
For a person watching their calories and fat, the can of tuna is likely the better buy. If additional
calories are needed, the protein supplement is a good choice, too. As you can see, when
evaluating foods and supplements, it’s wise to take into consideration the number of calories
that will be added to your plate as well as other nutrients such as fat, vitamins, and minerals.
This will help assure that you’re getting all the nutrients you need without consuming excessive
amounts of calories.
Summary
Slide 29
This module reviewed the nutrient, protein. We’ve learned that protein plays an important role
in our health. While protein is most often linked with growth and repair of the body, we’ve
learned that it’s important for the synthesis of many enzymes and hormones that our body
needs to function. It can be used as a source of energy – but only when needed.
Protein is found in a variety of foods. It’s recommended that protein foods be selected carefully
in order to maximize nutrition without exceeding calorie intake. Whenever possible, choose
lean protein foods, such as lean meat or poultry, fish, beans, and peas. If you’re following a
vegetarian diet, you shouldn’t have a problem getting enough protein if you include beans,
peas, nuts, seeds, or soy foods on your plate.
Finally, use caution if you’re considering protein or amino acid supplements. While some
products can help boost your protein intake, some are high in calories and fat. Plus, there isn’t
enough research to show that they’re beneficial for healthy people. Our body is designed to get
most of its nutrition from foods, and that’s where we should start.
References and Additional Resources
Duyff RL. Amerian Dietetic Association Complete Food and Nutrition Guide, 4th Edition, 2012.
Westerterp-Plantenga MS, Nieuwenhuizen A, Tome D, Soenen S, and Westerp KR. Dietary
Protein, Weight Loss, and Weight Maintenance. Annu. Rev. Nutr. 2009; 29:21-41.
Fulgoni VL. Current Protein Intake in America: Analysis of the National Health and Nutrition
Examination Survey, 2003-2004. Am J Clin Nutr. 2008; 87(suppl): 1554S-7S.
Craig WJ, Mangels AR. Position of the American Dietetic Association: Vegetarian Diets. J Am
Diet Assoc. 2009: 109: 1266-1282.
Whitney E, and Rolfes SR. Understanding Nutrition, 10th edition. Thompson Wadsworth, 2005.
Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids,
Cholesterol, Protein, and Amino Acids. Washington (DC): The National Academies Press; 2002.
U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary
th
Guidelines for Americans, 2010. 7 Edition, Washington, DC: U.S. Government Printing Office,
December 2010.
Web Resources:
U.S. Dietary Guidelines for Americans: http://www.cnpp.usda.gov/DGAs2010PolicyDocument.htm
MyPlate: http://www.choosemyplate.gov/
Academy of Nutrition and Dietetics: http://www.eatright.org/
USDA Nutrient Database: http://www.nal.usda.gov/fnic/foodcomp/Data/SR13/sr13.html
SuperTracker: http://www.choosemyplate.gov/supertracker-tools/supertracker.html
Fish4Health: http://fn.cfs.purdue.edu/fish4health/
This module was developed by:
Jenna Anding, PhD, RD, LD
Associate Professor and Extension Nutrition Specialist
Texas A&M AgriLife Extension Service
2012