What is a protein?
Protein is a macronutrient, providing four calories per gram. Proteins are made up of amino acids, small building blocks that come together in various combinations to make the macronutrient protein. There are twenty kinds of amino acids. Eleven of these are nonessential amino acids, which just means the body is capable of synthesizing them. That leaves nine remaining essential amino acids, which the body cannot make on its own. This means we need to get them from an outside source – food!
Related Reading: What is a Calorie?
These twenty amino acids link together in thousands of combinations, end to end, to form long chains with peptide bonds. That’s a fancy way of saying that they make a long conga line and form thousands of different kinds of proteins, depending on how they’re lined up. You can see these bonds being broken when a protein is exposed to acid or heat, also called denaturation. Ever fried an egg? When you first crack it, the “white” of the egg is actually clear, but as you expose it to heat in the skillet, it turns white! You’re witnessing proteins breaking up into amino acids. Science!
Our stomach is an acidic environment. When we swallow food that have proteins, it is in the stomach that they begin breaking down into amino acids, which is how they are absorbed. From there, our cells decide which proteins the body requires and recycles the amino acids to rebuild the proper protein. It’s like legos!
What do proteins do for my body?
We’re all aware that proteins help to build strong muscles, but they’re so much more than that! They’re actually in every cell in your body, as part of the structural cell wall. Protein also helps to build bones and teeth, which, in order to be formed, require a network of collagen (a type of protein) to be laid down first. Protein is in your artery walls, helping them to withstand changing blood pressure. It’s even in your skin! Any time you are growing or repairing damage, proteins are hard at work to create new tissue (including muscle). This is why proteins are so important in growing kids!
Not only that, but proteins also act as enzymes, or helpers with certain chemical reactions, hormones, which send messages to your body indicating a change must be made, regulators of fluid and acid-base balance, transporters of other molecules in the blood, and antibodies! That’s a lot of roles to fill. If your body is low on carbohydrates, protein will even act as energy for your cells – but there’s a good reason to avoid that. Click here to read about low carb diets and how proteins are affected.
Where can I get protein in my diet?
Protein is found in a ton of foods, both animal- and plant-based. Some foods are complete proteins, which mean they contain all nine of the essential amino acids. Other foods may only contain a few essential amino acids, and are called incomplete proteins. By mixing and matching incomplete proteins, you can use complementary proteins to build a complete protein. This would mean if food A has five essential amino acids, and food B had the remaining four essential amino acids, consuming them together would be complementary and provide a complete protein! (A great example of this is rice and beans!) Here are some foods in which you’ll find protein:
- Meats, Poultry, and Fish all contain 7 grams of protein per ounce!
- Choose lean proteins to save on calories
- Eggs also contain 7 grams of protein per egg! They are actually considered the reference protein, a perfect combination of all essential amino acids.
- Milk and dairy products. Milk has 8 grams of protein per cup (8 oz).
- Nuts, seeds, and legumes have anywhere from 2-7 grams of protein per ounce, depending on which one you choose. Think almonds, cashews, peanuts, sunflower seeds, peas, and every kind of bean on the planet!
- Vegetables and grains even have 2-3 grams of protein per serving!
What’s your favorite source of protein? If you’re vegetarian, do you use complementary proteins to get complete proteins in your diet? Let me know in the comments!