Protein is a very essential macro-nutrient. As we may know, protein supports the growth and maintenance of body
tissues. Below are 8 different types of protein, along with their specific
functions in the human body.
Hormonal: Hormones are protein-based
chemicals and they are secreted by the cells of the endocrine glands. They act
as chemical messengers, and transmit signals from one another. An example of a
hormonal protein is insulin. Insulin is secreted by the pancreas in order to
regulate the blood sugar levels in your body.
Enzymatic: Enzymatic proteins accelerate
metabolic processes in cells. Some functions of these proteins are liver
functions, stomach digestion, blood clotting and converting glycogen to
glucose. An example of enzymatic proteins is digestive proteins that break down
food for your body to
absorb.
Structural: Structural proteins, otherwise
known as fibrous proteins, are necessary to our bodies. Types of structural
proteins are collagen, keratin and elastin. The main structural component in
our hair, nails, skin and teeth is keratin.
Defensive: Defensive proteins are what we
know best as antibodies. They are the core part of our immune systems, and are
much needed to fight of diseases. These antibodies attack bacteria, viruses and
other harmful microorganisms, and they are formed in the white blood cells.
Storage: Storage proteins store mineral
ions mainly. An example of a storage protein is ovalbumin and casein.
Transport: Transport proteins carry
important and very vital materials to the cells. Hemoglobin, serum albumin and
calbindin are all examples of transport proteins. Each of these transport proteins
are being used in functions in our body that are vital in everyday life.
Receptor: Receptor proteins, found on the
outer part of cells, control the substances which enter and leave the cells. Examples
of what they could control are water and nutrients. Some of these receptor
proteins can activate enzymes or even stimulate endocrine glands.
Contractile: Contractile proteins regulate
the strength and speed of heart and muscle contractions. Contractile proteins
are also known as motor proteins. Myosin and actin are types of contractile
proteins.
How
Much Do I Need?
Protein - an essential nutrient
that a body required to build and repair muscle tissue is found in many foods
you probably eat on a daily basis. How much protein is necessary? A typical
person’s needs for protein are around 0.8-1.0 grams of protein per kilogram of
body weight. If you’re interested in calculating your needs, take your weight
in pounds divided by 2.2 to get your weight in kilograms. If a normal person
needs 0.8-1.0 grams/kilogram, then how much more protein does an athlete need?
The Academy of Nutrition and Dietetics (AND) recommends 1.2-1.7 grams/kilogram
for power athletes (strength or speed) and 1.2-1.4 grams/kilogram for endurance
athletes.
For Athletes
Muscle milk and protein powders
are on the rise within the bodybuilding and athlete community. What is the
purpose of them and what can they do that food can’t? Many athletes consume
more protein than necessary through supplements and powders, when in reality
they probably consume their daily recommendation from food alone. Some great
food sources of protein are: milk, eggs, meat, and beans. However, according to
AND, “Recent studies have shown that high-quality proteins such as whey,
casein, and soy can effectively be sued for the maintenance, repair, and
production of skeletal muscle proteins in response to weight training.” A few
tips if you are selecting protein powders:
- Look for whey or soy protein isolate as the first ingredient
- Choose low fat options with high protein (<3g fat, <5g sugar, and >20g protein are good starting places)
- If you are adding flavor to your protein powder, look for low-fat or natural flavors such as fruit
- Remember: you can meet (nearly) all protein needs through food intake!
For Heart Health
We’ve heard many times how too
much protein, specifically saturated fat, can increase cholesterol levels. It
should come as no surprise that protein supplements can also impact plasma
lipids. Because of soy protein’s structural similarity to estrogen, it also has
been proven to increase high-density lipoprotein (HDL) and decrease low-density
lipoprotein (LDL) in some cases. In other studies, it was said to have no
effect on HDL. Other research tailored to phytosterol supplementation revealed a
fall in LDLs, but showed no effect in HDL when the steroid compound was taken.
Some of these protein supplements have been proven to impact cholesterol levels
in modest amounts, making them potentially helpful in combatting the risk of
cardiovascular disease. While taking protein supplements in excess may have
some side effects, taking them to improve heart health could possibly be
useful.
For the Aging Adult
For the aging adult,
maintaining lean muscle mass is paramount. By continuing regular exercise, we
can maintain flexibility, range of motion, and quality of life through physical
function. But did you know that supplementing your diet with whey protein, your
workouts can have better, lasting effects on your body composition? In an
article published just recently, elderly adults with a mean age of 80.3 years
old, that also have sarcopenia (age related loss of muscle mass), were provided
post exercise shakes after performing resistance exercise programs over twelve
weeks. The participants received 22 grams whey protein and Vitamin D
supplementation compared to the control group that performed the same workouts
without the dietary supplementation. Those receiving the supplementation
obtained the best results by decreasing their body’s fat mass and increasing
their muscle mass. To avoid age related loss of muscle and fat mass gain, it is
best to continue exercising and enjoy some calcium and protein rich dairy after
your workout.
Over-supplementation
Protein supplementation when
done correctly can be a great exercise enhancement. However, is there such a
thing as too much protein supplementation? Yes. Taking too much of a protein supplement
can lead to a plethora of negative effects. In most cases, over supplementing
can end in dehydration, weight gain, significant stress on the liver and
kidneys, as well as hypercalciuria (excessive calcium in the urine). Why is
this so worrisome? Dehydration can impede athletic performance as well as
inhibit adequate electrolyte balances in the body. Weight gain occurs because
all of the excess protein is stored as fat. Hypercalciuria overloads the
kidneys and can induce kidney failure. Over time, the stress that is
placed on the liver and kidneys impairs their functions, and eventually causes
them to fail. Protein supplementation can be great for a short term basis, but
should be reconsidered in a long term plan.
References
Academy of Nutrition and Dietetics: eatright.org
Escott-Stump, S. (2012). Nutrition and Diagnosis-Related Care. (7th ed). Baltimore, MD: Lippincott, Williams & Williams.
Mahan, L., Escott-Stump, S., & Raymond, J. (2012). Krause's Food and the Nutrition Care Process (13th ed). St. Louis, MO: Elsevier/Saunders.
Mooradian, A., & Haas, M.
(2014). The effect of nutritional supplements on serum high-density lipoprotein cholesterol and apolipoprotein a-i. American
Journal of Cardiovascular Drugs, 14(4),
253-274. doi:10.1007/s40256-014-0068-1
Rondanelli, M., Klersy, C., Terracol, G., Talluri, J., Maugeri, R., Guido, D., Faliva, M., Perna, S. (2016). Whey protein, amino acids, and vitamin D supplementation with physical acitivity increases fat-free mass and strength, functionality, and quality of life and decreases inflammation in sarcopenic elderly. American Journal of Clinical Nutrition. Advance online publication. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/26864356
Woods, P. (n.d.) Eight types of protein and
their function. Retrieved from: http://healthyeating.sfgate.com/eight-types-protein-function-4559
