- Protein is in each of the trillions of cells in the human body. There could be no life without protein. The only other substance more plentiful in the body is water. Approximately 18-20% of the body is protein by weight.m
- The word “protein” is from the Greek word proteios, which means “primary” or “holding the first place.” The term was first used in 1883.d
- In 2010, 20-year-old athlete Ben Pearson tried to increase his protein intake to boost muscle development. However, no one knew he had a rare genetic disorder that prevented his body from breaking down protein. The increased protein intake increased ammonia levels in his blood that caused brain swelling and death.a
- Hair is made up of a protein called keratin, which forms a helical shape. This protein has sulfur bonds, and the more sulfur links it has, the curlier a person’s hair will be.g
- Protein, like carbohydrates and fat, is a macronutrient. Macronutrients are nutrients that provide calories or energy. Protein and carbohydrates each provide 4 calories per gram. Fat provides 9 calories per gram. The only other substance that provides calories is alcohol. However, alcohol is not considered a macronutrient because humans do not need it to survive.b
- The lifespan of most proteins totals two days or less. However, the recent discovery of extremely long-lived proteins may provide scientists with insight into cell aging and neurodegeneration.k
- Of all the cheeses, low-sodium Parmesan cheese has the most protein, with 41.6 grams per 100-gram serving.d
- The fish with the most protein is the Yellowfin Tuna, with 30 grams per 100-gram serving. It is followed by anchovies (29 g), salmon (27 g), halibut (27 g), snapper (26 g), and tilapia (26 g).b
- The older, larger, and more mature a bean grows, the more protein it has. Mature roasted soybeans have the most protein, with 39.6 grams of protein per 100-gram serving.b
Pumpkin seeds are a good source of protein
- Pumpkin and squash seeds provide 33 grams of protein per 100-gram serving. Watermelon seeds provide a little less than 28 grams per 100-gram serving.b
- While beef is the most popular meat in America, its protein content is low compared to poultry.b
- One of the smallest countries in the world, Luxemburg, is per capita the biggest meat eater. Luxembourgers eat on average about 300 pounds of meat annually per person. The U.S. comes in second with about 276 pounds of meat–mostly beef–per year. Austria is third with about 267 pounds of animal protein per person.e
- India, with a population of over 1 billion, eats the least amount of meat in the world with just 7 pounds of meat annually per person. Bangladesh comes in second, with 9 pounds, while the Democratic Republic of the Congo eats about 10 pounds of meat per person.e
- Cow used to be the global leader in meat eaten. The pig is now the most popular.e
- Proteins can have bizarre names. For example, the protein Pikachurin is a retinal protein that was named after a Pokémon character Pikachu. The protein Sonic Hedgehog was named after Sonic the Hedgehog. A blue protein is named Ranasmurfin, after the Smurfs.g
- Researchers have found that a mutation in a specific protein may raise the risk of autism. Specifically, when a protein called the Shank3 protein mutates, it leads to defects in neuron-neuron communication.j
- Without a protein called Albumin, the entire human body would swell.g
- Cataracts are caused by the denaturation of proteins in the lenses of the eyes.g
Insects can be a cheap and sustainable source of protein
- Insects are more nutritious than many other common forms of protein. For example, 100 grams of top sirloin beef contain 29 grams of protein and 21 grams of fat. However, 100 grams of grasshopper contain 20 grams of protein and just 6 grams of fat. Additionally, farming insects emits 10 times less greenhouse gasses than farming livestock.n
- A protein in semen acts on the female brain to prompt ovulation.l
- One typical human male ejaculation contains about 150 mg of protein.h
- Though there is some debate regarding protein intake requirements, the Recommended Dietary Allowances (RDA) suggests that protein should make up 10-35% of a person’s daily caloric intake. For example, a 180-pound male would need at least 80 grams of protein each day.g
- Errors in protein function can cause diseases such as Alzheimer’s and cancer, as well as prion diseases such as Creutzfeldt-Jakob disease (CJD) in which the brain degenerates to a structure that looks like a porous sponge.i
- The human body has about 100,000 different types of protein. The body needs protein to grow, heal, and carry about nearly every chemical reaction in the body.d
- The proteins in the body come in many shapes and sizes. The simplest proteins look like little trains, which lots of cars linked together. Each “car” or unit in a protein is called an amino acid. All the different types of proteins in the body have one thing in common: they are all chemicals made up of 20 kinds of amino acids.d
- Complete proteins (whole proteins) are proteins that contain all nine of the essential amino acids. Typically, proteins from animal foods such as meats, poultry, fish, dairy, and eggs are complete. Incomplete protein sources usually include nuts and vegetables.g
- Protein deficiency can cause serious health problems. For example, children with a protein deficiency could develop a condition known as Kwashiorkor. The symptoms include a protruding belly, thin hair, overall weight loss, and discolored skin and hair. Left untreated, it can lead to stunted growth, mental impairments, and death.d
The USDA categorizes eggs as “Meats” in the Food Guide Pyramid
- The protein in eggs is the highest quality of protein found in any food.c
- While most Americans eat nearly twice as much protein as their bodies need, 7.7% of adolescent females and about 8% of adult older women are reaching only the minimum recommended amount. Additionally, 13.4% of children are below the ideal range.g
- Protein helps make a meal more satiating which, in turn, helps people maintain a healthy weight. Just increasing protein from 15% to 30% of total calories and reducing fat from 35% to 20% of calories can result in sustained weight loss.b
- Inadequate protein/amino acid intake can affect the entire body, including 1) bone cell synthesis, 2) red blood cell production, 3) heart cell turnover rate, 4) neurotransmitters/mood, 5) immune function/antibodies, 6) enzymes/hormones, 7) skin elasticity/muscle tone, 8) organ function, 9) pH balance, and 10) mobility and joint integrity.m
- Middle- aged and elderly people have more extensive body breakdown than a younger person, which means they need more protein. However, as people enter middle age, hydrochloric acid, which helps digest protein in the stomach, drops to half its regular level. Because protein is crucial in cell regeneration, some researchers suggest that most of aging is due to this drop alone.m
- Protein deficiency is rare in developed countries. Even a vegetarian diet typically provides all the protein the body needs when a diet includes a wide variety of plant food.g
- Vegetarian sources of protein include legumes (pulses), nuts, seeds, and fruits. Plants that are poor in protein include roots and tubers, such as yams, cassava, and sweet potatoes.g
Too much protein can harm the body
- Eating too much protein can be dangerous for the body. For example, high levels of protein can stress the livers and kidneys because they have to work extra hard to dismantle and dispose of the extra protein. Excess protein can also lead to weight gain.b
- Proteins in the human body have many jobs. For example, a protein called rhodopsin in our eyes helps us see light. Hemoglobin in red cells carries oxygen from the lungs to the body’s cells and takes away their harmful waste product, carbon dioxide. A series of chemical reactions involving proteins makes the blood clot. Additionally, proteins give the body structure, help regulate body processes, defend against disease, maintain the body’s internal environment, and give us energy.g
- While human meat is a good source of high-quality protein, cannibalism was not historically motivated by diet or starvation. Rather it was a symbolic gesture, usually as a way to commune with the gods.g
- Because animal proteins are more similar to our proteins than are plant proteins, they are used more readily and rapidly. In other words, our bodies can use animal proteins slightly better than plant-based proteins. However, some meat is loaded with unhealthy saturated fat. The healthiest choice of meat is lean meat low in saturated fat.f
- Proteins found in certain foods are often the cause of allergies because the structure of a protein may trigger an immune response. For example, many people are allergic to gluten, the protein in wheat and other grains.g
The Twenty Amino Acids in Human Proteins m
|Aspartic acid (D)
||Glutamic acid (E)
*Essential amino acids, which our bodies need but can’t make from other sources
Protein Requirements Change with Age g
||Protein Needed (in grams)
Protein Ratings Based on Biological Value, or How Well the Body Uses Protein c
-- Posted November 20, 2012
a Allen, Jane E. “High-Protein Diet Factored into Athlete’s Sudden Death.” ABC News. October 7, 2010. Accessed: October 23, 2012.
b Eades, Michael, M.D., and Mary Dan Eades, M.D. 2000. The Protein Power Lifeplan. New York, NY: Warner Books, Inc.
c “How Our Bodies Use Protein.” BodyBuilding Pro. 2012. Accessed: October 23, 2012.
d Ivanoff, George. 2001. Protein (What’s in My Food?). Mankato, MN: Smart Apple Media.
e Kennedy, Lesley. “Which Country Eats the Most Meat? It’s Not U.S.” Recipe. May 4, 2012. Accessed: October 23, 2012.
f Kimball, Molly. “Is Plant Protein (Such As Soy) As Good As Animal Protein If I Want To Build Muscle?” ABC News. July 1, 2009. Accessed: October 30, 2012.
g Larsen, Laura, ed. Diet and Nutrition Sourcebook (Health Reference Series). 2011. Detroit, MI: Omnigraphics.
h Lestari, Ayu Wandira. “Some Facts About Sperm.” IYM Health. September 22, 2012. Accessed: October 30, 2012.
i Pietzsch, Joachim. “Protein Folding Disease.” Horizon Symposia. 2003. Accessed: October 30, 2012.
j “Protein Found in Brain Cells May Be Linked to Autism.” BBC New. March 20, 2011. Accessed: October 23, 2012.
k Salk Institute for Biological Studies. “Why Do Cells Age? Discovery of Extremely Long-Lived Proteins May Provide Insight into Cell Aging and Neurodegenerative Diseases.” Science Daily. February 3, 2012. Accessed: October 23, 2012.
l “Sex and the Female Brain: Protein in Semen Acts on Female Brain to Prompt Ovulation.” Science Daily. August 20, 2012. October 30, 2012.
m Silverstein, Alvin Dr., Virginia Silverstein, and Robert Silverstein. 1992. Proteins (Food Power). Brookfield, CT: The Millbrook Press.
n Weiner, Miriam B. “Countries That Eat Bugs.” U.S. News Travel. 2012. Accessed: October 23, 2012.