The first step to learning about
protein is knowing how to spell it. General rule is “i” before “e” except after
“c”, right? Wrong. Protein is one of those weird words where the
“e” comes before the “i”. Now that you’ve read this, I expect you to get it
right! Proteins are the building blocks of our bodies, and of the foods that we
eat. Proteins are made up of small molecules bonded together—these small
molecules are called amino acids (AAs).
AAs consist of a carbon, hydrogen, oxygen and nitrogen. Nitrogen is the
main differentiating quality of proteins from the two other macronutrients. The
central carbon (with 4 bonds) is bonded to a nitrogen ion, an acid, a hydrogen,
and an “R” group that can be various carbon chains depending on the specific AA.
Here is a visual.
There are different classes
of AAs based on their structure, they are called basic or branched-chain
AAs. Basic AAs are those that the R group is one simple chain, the carbon of
the R group attached to the central carbon only bonds to one other carbon. Branched-chain
amino acids (BCAAs) are those where the carbon of the R group is bonded
to 3 other carbons. BCAAs are typically used for fuel by muscles, especially
when injured or strength training.
AAs can also be classified as essential or non-essential.
Our bodies need 20 common AAs that bond together in various ways in order to
facilitate our body’s daily processes. 11 of these AAs are deemed non-essential
meaning that our bodies can make these AAs with left-over parts from other AAs.
Therefore, there are 9 essential AAs that we need to consume through our diet
in order to provide our bodies with the full 20. In addition, if we consume any
of the 11 non-essential AAs, our bodies will use them directly instead of
manufacturing them.
Dietary protein provides all 9
essential AAs that our bodies need as well as providing “spare parts” for our
bodies to make the non-essential AAs. Animal sources of protein (meat, fish,
poultry, eggs, etc.) contain all 9 essential AAs—these are called complete proteins. However, plant
sources of protein usually do not contain all of the essential AAs in one plant
(with the exception of soy and quinoa) thus they are called incomplete proteins. When eating a vegetarian
diet, it is important to focus on complementary
proteins that pair together make a complete protein (containing all 9
essential AAs). As seen in the picture below, you can pair two of the following
foods to make a complementary protein: dairy, nuts/seeds, grains, and legumes.
So how does it work? Let’s pretend
you’re building a car (complete protein) with parts (AAs) from different body
shops (plant protein sources). One shop (legumes) brings you 3 tires, a
steering wheel, brakes, seats, and an engine. Another shop (grains) brings you
2 tires, the body/frame, 3 steering wheels, brakes, seats, and 2 engines. You
now have all of the parts you need to make the car (4 tires, the body/frame, a
steering wheel, engine, brakes and seats) but you also have extra parts (1 tire,
1 set of brakes, 1 set of seats, 2 engines, and 3 steering wheels) to go
towards making another car, making the limiting
amino acid the body/frame because it came in the lowest quantity and
inhibited our body to make a second car. Make sense?
Proteins are made up
of specific “shapes”, and when they are exposed to heat, acidic or basic substances, or agitation they change shape and are no longer biologically
functioning proteins. This can be seen by cooking an egg—the protein (egg white)
starts out clear, and as the heat penetrates the proteins they change shape and
turn an opaque white color. Or you can think of beating egg whites to
What do proteins do for our bodies?
Every cell is made up of proteins. Proteins provide the structure/walls/scaffolding
for pretty much every part of our bodies. This means that when cells die, like
they’re supposed to (dead skin, hair, etc.), we need more proteins to make
replacement cells. Proteins also maintain bodily fluid balance, participate in
acid/base balance, help in the production of hormones and enzymes, aid in
immune health, make glucose for the brain (when necessary), act as an energy
source, and aid in satiation.
The average person
needs 0.8 grams of protein for every kg of body weight each day. Gerald weighs
175 lbs. which is 79.4 kg. 79.4 kg × 0.8 g/kg = 63.52 g protein per day. That’s
really cool information, but that’s not exactly what we order at a restaurant,
right? Well, 1- 4 oz. portion of chicken contains approximately 35 g of
protein. A Clif Bar has anywhere from 7-14 g protein… this adds up fast! Protein
is valued higher than the other macronutrients in our society due to fad diets
and poor media. We really do not need to focus on protein as much as we
typically. A typical American eating 2 eggs at breakfast (12 g), a turkey
sandwich at lunch (14 g), and a 4 oz. steak at dinner (36 g), with snacks in between
(15-30g), would easily over-shoot their protein needs for the day. According to
the Acceptable Macronutrient Distribution Ranges, protein is only supposed to
be 10% to 35% of our daily intake. You can calculate how much this is by going
backwards—if you are eating an 1800 kcal/day diet, 10% of that is 180
calories—there are 4 kcals/gram of protein so in order to consume
What happens if you eat too much
protein? Just like all excess calories, excess protein can be converted into
fat and stored for future use as energy. Diets high in protein are often times
simultaneously low-carb diets. Meaning that these high-protein/low-carb diets
are withholding the brain’s preferred energy source, low in fiber for gut
health, possibly lacking vitamins, and have the possibility (depending on your
protein source) of increasing blood cholesterol levels with increased saturated
fats. In extreme cases there could be organ damage, disease development, and
toxicities.
When we do not eat enough protein
or have a medical condition that requires increased protein needs it is
possible to develop protein energy malnutrition. This is displayed in two
different conditions, Kwashiorkor and Marasmus. Kwashiorkor patients present
with very large and distended bellies while maintaining some fat stores—they are
malnourished patients with an additional condition such as infection. Marasmus
patients show a skeletal-like appearance—they are extremely malnourished
patients (protein and other nutrients). These visuals are only in chronic
cases—it is possible to have protein energy malnutrition without exhibiting these
physical attributes.
Overall—it is important to eat
proteins, and eat them in an informed way. If you are a meat eater, feel safe
in knowing that they’re bringing all the parts you need to make a car. If
you’re a vegetarian, remember to eat a variety of protein foods throughout the
day in order to gather all the parts you need for your car. There’s no need to
stress about proteins, it is likely that you’re getting what you need
throughout the day if you are following BALANCE,
VARIETY, and MODERATION.
Wardlaw,
G. M., & Hampl, J. S. (2007). Perspectives in nutrition. Boston:
McGraw-Hill Higher Education.
Auntie Madeline’s Peanut Chicken
2 lbs. chicken tenderloins
1/3 c peanut butter
2 Tbsp. honey
2 Tbsp. soy sauce
1 clove garlic, chopped
½ tsp. red pepper flakes
Mix peanut butter, honey, soy sauce, garlic, and red pepper
flakes in a bowl. Toss with chicken tenderloins and marinate for at least 1
hour in refrigerator.
Slide chicken pieces on previously-soaked skewers and
barbecue, turning often, until cooked thoroughly. Eat with coleslaw, rice, and
a cold beverage on a picnic table in the back yard.
You can also bake them at 400° for 30 minutes, but they’re
better barbecued
- --Madeline Herzog
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