Transcript 5. Functions of protein

Protein, Anyone?
©2005 Thomson-Wadsworth
Key Questions
•
What are proteins made of?
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What are the three essential
functions of protein?
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What does the body need to make
protein tissues?
• Protein gets a
positive press
• People know protein
is important
• Nearly all in U.S. get
enough protein
• 15% of total calories
in U.S. adult diet
supplied by protein,
far above what we
need.
• Term protein is derived from the Greek
word protos for “first”
• Indicates importance
• Essential structural component of all life
• Involved in most biological processes
Four Functions of Protein
• Integral structural component of skeletal muscle,
bone, connective tissues, organs, red blood cells
and hemoglobin, hair, and fingernails
–Collagen is most common protein
• Basic substance that makes up digestive and
other enzymes in the human body
• Major component of hormones such as insulin
• NOT ESSENTIAL: also serves as an energy
source
Protein Dynamics
• A 154-pound man has 24 lbs of protein
• All protein is broken down and re-built
• Protein turnover uses 9 oz each day
• We only lose (need to consume) 2-3 oz
per day
Protein Dynamics
• Most protein is recycled from protein
substances being ‘turned over’
• Proteins play key roles in repair of
tissues and replacing tissue proteins
damaged by illness or injury
Source of Energy
– Protein also serves as a source of energy
– Protein contains nitrogen, not stored
– For energy, amino acids first lose nitrogen
– Free nitrogen in excess excreted in urine
– Nitrogen excretion increases need for water
– Amino acids converted to glucose or fat, then
used to form energy
Amino Acids
•The “building blocks” of protein are amino acids
•Protein in food is broken down by digestive enzymes
and absorbed into the bloodstream as amino acids
•20 common amino acids form proteins when linked
together
•Each type of protein in the body is a unique
combination of amino acids linked together in chains
•DNA is genetic material that directs protein synthesis
and organizes amino acids into chains
Alanine: A Simple Amino Acid
• Carbon - grey
• Hydrogen - white
• Nitrogen - Blue
• Oxygen - Red
Assembling a
protein is called
translation.
mRNA travels
from the nucleus
of a cell to the
ribosomes, where
proteins are
assembled.
Protein Structure
Protein Structures:
The Hormone Insulin
• For each protein,
its chain of amino
acids fold up into a
unique, complex
shape
• Insulin proteins
function because of
their unique shapes.
Amino Acids
Proteins Differ in Quality
• How proteins in our food support our
body's amino acid needs is protein
“quality”
• High quality have a balance of
essential amino acids to support
tissue needs
• If essential amino acids are missing,
proteins can not be built
Proteins Differ in Quality
• Protein (amino acids) is not stored in the
body, so we need essential amino acids
daily
• We need foods that provide enough
protein EVERY DAY.
• We need foods that provide enough of all
essential amino acids EVERY DAY.
Complete Proteins
• Food sources of high-quality protein are called
complete proteins
• Complete proteins include those found in animal
products and soy products
• They have the right balance of amino acids
needed to make and maintain animal bodies
(and ours)
Incomplete Proteins
• Incomplete proteins are deficient in one or more
essential amino acids
• Most plant proteins are “incomplete” but
incomplete in different ways
– Lack different amino acids
• Vegetarians combine plant foods to obtain
complete proteins.
• More on Vegetarianism
shortly
Amino Acid Supplements
• Amino acids are natural, so people think
they’re harmless
• But high intakes of amino acids can harm
health
• High amounts disrupt protein synthesis by
causing a surplus of some amino acids
and a deficit of others
• (see more at end of ppt)
Protein Needs
• Average intake in the U.S. is 75 grams
per day
• RDA: 56 grams for men
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46 grams for women
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OR 8 grams of protein for every 20
pounds of body weight
Food Sources of Protein
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Tuna 3 oz.
24 grams
Beef steak 3 oz.
26 grams
Milk 16 oz.
16 grams
Cereal and bread
12 grams
(6 servings) ____________
• Total
78 grams
• RDA for protein, men: 56 grams
Food Sources of Protein
• Milk, 16 oz.
16 grams
• 1 cup oatmeal
6 grams
• Peanut butter
sandwich
16 grams
 2 bean burritos
28 grams
1 cup Spanish rice
4 grams
_________________________________
70 grams
Kwashiorkor
(inadequate
protein) and
Marasmus,
protein and calorie
malnutrition
Marasmus
• Occurs with famines and
poverty
• Occurs with anorexia
nervosa and diseases such
as cancer and AIDS
• Victims have little body fat
• Must utilize protein from
muscles, liver, and tissues
as an energy source
Is There Enough Protein for All?
• From mammals:
– Expensive
– Scarce
• Poultry & Fish
• Plant sources
• Insects
– Abundant
– Traditional in many
cultures
At the Other Extreme…
Trends
• 2/3 of U.S. protein comes from animal
products
• Wealth leads to meat protein increase
• Increased consumption of fat, too
• Rates of heart disease and some cancers
increase
Too Much Protein?
• Adults can consume 35% of total calories
without immediate ill effects
• Consumption of 45% of total calories from
protein is too high
• This much protein causes nausea, weakness,
and diarrhea; diets very high in protein result in
death after several weeks
• People are cautioned not to consume high levels
of protein from foods or supplements
Problems with High Protein Intakes
• Generally accompanied by high-fat and lowfiber intakes
• Foods high in protein (hamburger, cheese,
eggs) are often high in saturated fat and
contain no fiber
• Even lean meats provide a large part of
their total calories as fat
– Calories from lean sirloin steak are 37% fat
and 63% from protein
Problems with High Protein Intakes
• "Eating even small amounts of red meat,
especially processed red meat, on a regular
basis is linked to an increased risk of heart
disease and stroke, and the risk of dying from
cardiovascular disease or any other cause."
– www.hsph.harvard.edu/nutritionsource/whatshould-you-eat/protein/
Meat and Cancer
• some data shows that eating a lot of red meat
and processed meat is linked to an increased risk
of colon cancer
• In the Nurse’s Health Study and the Health
Professionals Follow-Up Study, every additional
serving per day of red meat or processed red
meat was associated with a 10 and 16 percent
higher risk of cancer death, respectively
– www.hsph.harvard.edu/nutritionsource/what-should-youeat/protein/
Vegetarian
Diets
Famous Vegetarians
Socrates, Plato, Pythagorus, Plutarch, Leonardo da Vinci, Tolstoy, Shelley,
George Bernard Shaw, Thoreau, Gandhi, Johnny Weissmuller (the first
“Tarzan”), Bob Dylan, Joanna Lumley, Paul McCartney, Paavo Nurmi (“The
Flying Finn” - 9 Olympic gold medals), Martina Navratilova, Chris Evert, Peter
Brock, Greg Chappell, Carl Lewis, Killer Kowalski (champion wrestler), Julie
Christie, Gillian Anderson, David Duchovny, Alec Baldwin, Kim Basinger, Drew
Barrymore, James Cromwell, John Cleese, Penelope Cruz, Joaquin Phoenix,
Eric Stoltz, Reese Witherspoon, Steven Seagal, Brooke Shields, Gwynneth
Paltrow, Terrence Stamp, Willem Dafoe, Richard Gere, Ellen Burstyn, Woody
Harrelson, Ashley Judd, Guy Pearce, Alicia Silverstone, Steve Martin, Jude
Law, Mariel Hemingway, Barry Gibb, Bryan Adams, Joan Baez, Damon Albarn,
Kate Bush, Leonard Cohen, Dennis Weaver, Ian McKellen, Brian May, Bob
Marley, Melissa Etheridge, Peter Gabriel, kd lang, Ricky Martin, Belinda
Carlisle, Billy Idol, Shania Twain, Alanis Morissette, Chrissie Hynde, Moby,
Meatloaf, Christie Brinkley, Chelsea Clinton, Ricki Lake, Jerry Seinfeld.
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KEY CONCEPTS AND FACTS
• Vegetarianism is part of a
lifestyle with many
attitudes and behaviors
• Vegetarian diets are
health- promoting
• Traditional vegetarian
diets provide a wide
variety of nutritious
foods.
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Reasons for Vegetarianism
• Vegetarians number in the hundreds of millions
• Much of world is vegetarian because meat is scarce and
expensive
• People may adopt vegetarian diets because of:
– religious beliefs
– humanitarian concerns
– desire to cause no harm to animals
– desire to preserve the environment
– desire to preserve food supply by “eating low on the food
chain”
– believe that animal products are unhealthful or unsafe
– want to keep their weight down
– want to lower the risk of cancer or heart disease
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Religions of India
• Hinduism (originated before 1200
BC)
• Jainism originated ~500 BC
• Buddhism originated ~500 BC
and spread to Tibet, China, and
Japan
Often Vegetarian due to reverence
for life and belief in karma and
reincarnation
• Plant foods have prana, life energy
• Ahimsa, not harming living beings
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Greek Philosophers
• Socrates, Plato, Epicurus and Pythagoras
advocated vegetarianism
for reasons of compassion:
“For as long as men massacre animals, they
will kill each other. Indeed, he who sows the
seed of murder and pain can not reap joy and
love.”
Pythagoras ~530 BC
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Christianity
• Christian vegetarian traditions include Trappist
monks and many others, motivated by compassion
and also a desire to live simply.
• “Not to hurt our humble brethren (the animals) is
our first duty to them… men who will exclude any of
God’s creatures from the shelter of compassion and
pity, will deal likewise with their fellow men.”
St. Francis of Assisi, c. 1200
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Protestant Vegetarian Movement
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Began in England in early 1800’s
Health was the main concern
Belief that meat was harmful to the body
U.S: Seventh Day Adventist Church, 1863
13 million members worldwide
“temperate and healthy lifestyle”
Church owns large vegetarian food companies
Many church members today are lacto-ovo
vegetarians
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East Meets West
• Mahatma Ghandi:
• "The greatness of a nation can be judged by
the way its animals are treated."
• Martin Luther King, Jr:
• - "One day the absurdity of the almost
universal human belief in the slavery of other
animals will be palpable. We shall then have
discovered our souls and become worthier of
sharing this planet with them."
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Health & Environmentalism
- "Nothing will
benefit human
health and
increase chances
of survival for life
on earth as much
as the evolution to
a vegetarian diet."
- Albert Einstein
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Environmental Concerns
• Meat protein production
requires:
6-17 times more land
4-26 times as much
water
up to ?? times as much
fossil fuel as the
equivalent amount of
vegetable protein
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• UN Climate
Change
Summit,
• Dec 2015
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Calories of Fossil Fuel Expended to Get
One Calorie of Protein
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Pounds of grain needed
to produce one pound
of bread compared to
one pound of animal
weight gain.
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Environmental Concerns
• Emissions of greenhouse gas, carbon dioxide,
biocides
• and compounds that cause acid rain
• are at least 6x greater for meat production
than for plant food production
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How Big is your Ecological Footprint?
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Humanitarian Concerns
• Farmland used to
produce animal feed.
• This land could support
5-10 X as many people
on a vegetarian diet.
• This may be a concern
in our lifetime.
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Fossil fuels in meat production
• If everyone in the U.S.
ate meatless just one
day a week, it would be
the environmental
equivalent of not driving
91 billion miles per year
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Today, world food supply is still
adequate
• Enough wheat, rice and other grains are produced
to provide every human being with 2,700 calories
a day.
• In addition, are vegetables, beans, nuts, root
crops, fruits, grass-fed meats, and fish
• But many people are too poor to buy readily
available food.
www.foodfirst.org
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From “Vegetarian Times”
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If you want to help animals…
If you want to help the environment
If you want to help your health…
If you want to enjoy your life…
…the simplest, quickest and most effective
thing to do is to become a vegetarian
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• If you were a vegetarian, what would your
reason be?
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Vegetarians
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Vegetarians? of Many Types
Flexitarians may
• eat much less meat than
American average
• Avoid all red meats
• Or avoid all meats except
seafood (pescetarians)
•American Vegetarian Society
says vegetarians eat no
meat, poultry, fish
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Vegetarian Diet Options
• Lacto-vegetarians
• Lacto-ovo
vegetarians
• Vegans
• Fruitarian, raw food,
etc
• The junk food
vegetarian diet
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Vegetarian Diet Options
• Can be very healthy
– Lacto-ovo vegetarians
– Lacto-vegetarians
– Vegans
• Can lead to malnutrition
– Macrobiotic Diet
– Fruitarian, raw food, etc
– The junk food vegetarian diet
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Vegan Diet & Philosophy
• Empathy for all creatures and appreciation and love
of ecology
• Live without consuming or otherwise harming
animals:
• Eat no animal products
• Avoid use of animal products
• This diet requires nutrition knowledge to be
adequate especially for pregnant women and
children.
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Vegetarian Diets and Health
• “Well-planned vegan and other types of
vegetarian diets are appropriate for all stages
of the life cycle, including during pregnancy,
lactation, infancy, childhood, and
adolescence
• Official position of the U.S. Academy of
Nutrition and Dietetics (U.S.) and Dietitians
of Canada
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Benefits to Health
• Vegetarian diets beneficial for health and disease
prevention
• Vegetarians in developed countries generally have
adequate protein intakes
• Vegetarianism lowers risk of heart disease, stroke,
hypertension, type 2 diabetes, chronic bronchitis,
gallstones and kidney stones, and colon cancer
• Vegetarians rarely become obese or develop high
blood cholesterol
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Health and Longevity
• One research study showed that life
expectancy of a 30-year-old vegetarian
Adventist woman was 85.7 years,
6.1 years longer than average
• For a vegetarian Adventist man, life
expectancy was 83.3 years, 9.5 years longer
than average
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• Variety
– Fruits
– Vegetables
– Grains
– Nuts
– Seeds
– Beans
– Dairy
– **
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Special Considerations
• Diets with few or no animal products may be
low in sources of complete protein, iron,
vitamin B12, vitamin D, calcium, and zinc
• With a good traditional diet or with
knowledgeable food selection, nutrient
inadequacies will not occur
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Plant Protein Sources
• Animal products provide all nine essential amino
acids in the right balance
• Soy proteins are complete protein sources for
children and adults
• Body needs sufficient essential amino acids to build
and replace protein substances
• If essential amino acids are missing, protein
construction stops, and available amino acids are
used for energy
• Remember, essential amino acids are not stored,
body needs fresh each day
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Amino Acids low in some plant foods:
• Grains are low in Lysine
• Legumes are low in Sulfur-containing amino acids:
• Methionine
• Cysteine
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Vegetarian diets combine complementary plant
foods
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Grains
Dairy Products
Seeds:
Sesame, sunflower
Legumes
Incl. peanuts
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Food Sources of Protein
• Milk, 16 oz. 16 grams
• 1/2 cup oatmeal 3 g
• Peanut butter
sandwich 16 g
1 cup rice and
beans
10 g
TOTAL
45 grams
A 50 lb. Child needs 25 grams
protein daily
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Plant Protein Sources
• Many combinations of plant foods yield complete
proteins
• Soy products will complement other plant proteins
• Milk and eggs, like meat, contain complete proteins
and will complement the essential amino acids
profile of any plant source of protein
• Complementary protein
sources should be consumed
throughout the day
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Vitamin B12
• Vitamin B12 naturally present only in animal
products
• Vegetarians who don’t consume animal products
can easily obtain vitamin B12 from fortified
products such as soy milk and breakfast cereals
or from a multivitamin or B12 supplement
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Vitamin D
• People get vitamin D from the sun and from milk
• Vitamin D is found in few foods- most of our intake
comes from vitamin D-fortified milk or soy milk
(cheese and yogurt seldom fortified)
• If milk is not part of the diet and exposure of the skin
to sunlight is limited, we need to get vitamin Dfortified soy milk, breakfast cereal, or a multivitamin
with vitamin D
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Calcium Sources
• Vegetarians who exclude milk and milk products rely
on:
• good plant sources of calcium (greens like kale,
broccoli, bok choy, and beans)
• and calcium-fortified products such as soy milk,
breakfast cereals, and orange juice
• If calcium supplements are used, they should include
Vitamin D.
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Flexitarian
• A semi-vegetarian or
flexitarian diet is plantbased with the occasional
inclusion of meat products
• Tony Gonzalez's daily 80/20
diet (80 percent plantbased/20 percent fish or
chicken).
– Retired from Atlanta Falcons
in 2013 at age 37
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The "Meatless Mondays" campaign
Can one day a week makes a difference?
First done in WW I to aid the war effort
Returned in WW II to help feed war-ravaged
Europe.
Revived in 2003 by Johns Hopkins Bloomberg
School of Public Health’s Center for a
Livable Future
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The "Meatless Mondays" campaign
Now a global movement -learn more at
http://www.meatlessmonday.com/
By pledging to go meatless on Monday just
for one month, you will reduce your carbon
footprint by almost 33 pounds. So for every
61 people who pledge, we reduce our
collective carbon footprint by about one
ton per month!
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The "Meatless Mondays" campaign
• Who's doing it?
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The "Meatless Mondays" campaign
• Who's doing it?
• On Facebook &
• Twitter
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Meat Free Mondays
• Plan your Monday menus
• What favorite vegetarian meals do you
already have?
• Southern "4 Vegetable Plate"
• Try new recipes for a few vegetarian main
dishes
• Ask your family to join, too.
• And tell a couple friends about it!
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Making a Difference
• Share your experiences
with "Meatless Monday"
campaign
• Global Eating video "Make
Meat a Part of the Meal,
Not the Heart of the Meal"
• Learn about low meat or
meatless meals from many
cultures
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end
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Amino Acid Supplements Can
• Cause loss of appetite, diarrhea, and
gastrointestinal upsets
• Increase the workload of the liver and
kidneys
• Increase risk of dehydration
• Only known benefit of supplements:
– Big Money-maker for Supplement
Companies!
Build Muscle?
• Amino acids and protein powders do NOT cause
muscles to grow
• No amino acids are delivered directly to our
muscles and cause muscles to enlarge
• Only exercise and a good diet
(and, too frequently, steroids!)
build muscles
• Most athletes get more than enough protein
from their usual diet
Macrobiotic Diet
• Philosophy values organic foods and balancing “yin”
and “yang” foods
• To maintain proper yin/yang balance, all extremely
yang foods and all extremely yin foods are avoided
• Yin foods: refined sugars, chocolate, tropical fruits, soda,
juices, coffee, etc.
• Yang foods: meats, eggs, dairy products, etc.
• Sometimes nutritionally adequate
• Not adequate for pregnant women and small
children
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Restrictive Vegetarian Diets
and Health
• Fruitarian diet, raw food diet and various “fad”
vegetarian diets are not nutritionally adequate
– Dangerous for pregnant women, children, and sick people,
who have high nutrient needs
Junk Food vegetarian or vegan diet
– Common food staples are: cheese pizza, potato chips,
soda, candy, macaroni and cheese, and all types of
packaged donuts, cookies, etc.
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