When it comes to nutrition, protein can sometimes be a controversial topic. How much do you really need? Are all sources of protein equivalent for our health? What are the ethical implications when choosing a dietary protein source? What is meant by “protein” in the nutrition facts? Why is protein important for our bodies in the first place?
To begin to understand these questions, you first need to know the basics of proteins in biology.
What are proteins for?
Proteins are the molecular building blocks that make up our bodies, accounting for approximately 1/5 of our mass as adults. Don’t forget that around 3/5 of our mass is water!
If proteins are the building blocks of humans, what are the building blocks of proteins? Proteins are made of molecules called “amino acids” that link together to form a chain. The chain, called a “peptide”, is folded into a shape that allows the protein to do its job in the body. Depending on the protein (there are ~100,000 kinds of proteins in the body) these jobs include building or repairing your muscle fibers (proteins like actin and myosin) and regulating your metabolism (insulin).
There are 20 kinds of amino acids used to make proteins in the human body. These are typically categorized as “essential”, meaning you need to get them from your diet, and “non-essential”, meaning they can be made for you in your body, usually from the glucose you eat.
There are 9 essential amino acids (Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan and Valine) and 11 non-essential amino acids (Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Glutamic acid, Glutamine, Glycine, Proline, Serine, and Tyrosine).
“Protein” in the Nutrition Facts
When a food label lists grams of protein, it is actually referring to the overall mass of amino acids in the food. This is important to know, because, as you learned above, some amino acids are more important to have in your diet than others! Some foods may be “high in protein” but still lack essential amino acids that your body needs! It’s so important to eat a balanced diet to make sure you’re getting all the nutrients and amino acids required to repair and maintain your body.
We sometimes hear people describe foods as a “complete” protein, which means the food contains all nine essential amino acids. Complete protein foods are convenient, but what matters most is that you’re getting enough of each essential amino acid throughout the day.
How much protein should you eat?
The recommended dietary allowance (RDA) for protein, meaning the daily amount of amino acids your body needs, is usually listed as 0.8g per kilogram of body weight. This means a person who weighs 165 pounds, or 75 kilograms, should consume 60 grams of protein per day. While this is a good start, some believe it’s more like a bare minimum required to survive; not necessarily enough to thrive. The right amount for you will depend on factors like how physically active you are and how rich and balanced your diet is in the nine essential amino acids!
What are good dietary sources of protein/amino acids?
What works for one person doesn't necessarily work for another, so it’s important to structure your diet to suit your own needs. That being said, a balanced diet low in processed foods is one of the best ways to support your health.
It’s common for people to choose their dietary protein sources while considering the ethical implications. Raising livestock, for example, has environmental and animal rights consequences; and many people thrive while sourcing their protein exclusively from plants and fungi. Whatever you decide, consider the following list of protein-rich foods next time you’re choosing what to eat:
beans, peas and lentils
brown, green or red or other lentils
peas such as chickpeas and split peas
dried beans such as black beans and kidney beans
fortified soy beverages, tofu, soybeans and other soy products
eggs
meats and poultry
beef, pork and wild game
turkey
chicken
nuts and seeds
peanuts
almonds
cashews
nut butters
sunflower seeds
fish and shellfish
trout
perch
shrimp
salmon
pickerel
sardines
mackerel
dairy products
milk
yogurt
cheeses
Key Takeaways
The proteins that make up your body are made of amino acids.
The nine “essential” amino acids need to come from protein in your diet.
Not all protein-rich foods are the same: the nutritional value of a protein-rich food depends on the amount and balance of essential amino acids.
When it comes to meeting your protein needs, the best way to nourish your body is to make sure you’re getting enough of each essential amino acid by eating a balanced diet, low in processed foods.
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