Protein is a macronutrient made up of amino acids. We need amino acids. They are the building blocks of protein and we need protein to live, grow, and survive. The three types of amino acids are:

Essential amino acids

Nonessential amino acids

Conditional amino acids

The Roles Proteins Play in the Body

  • Growth and maintenance of tissues and muscles

  • Enzymatic reactions

  • Digestive health

  • Energy and glucose

  • Immune regulation through the production of antibodies

  • Hormone production

Protein Quality and Digestibility

Protein digestibility depends on the source of the protein, as well as what other foods are eaten with it. Sorry vegans, but animal proteins are 90-99% digestible, while plant proteins are about 70-90% digestible. The animal proteins are more bioavailable than any plant proteins. Bioavailability refers to how completely something is absorbed by the body.

A high-quality or complete protein contains all nine essential amino acids in relatively the same amounts that our bodies require, but may or may not contain all the nonessential amino acids. Sorry again, vegans, but animal sources of protein provide higher quality protein. Protein from plants tends to be limited in one or more essential amino acids.

Complete proteins: meat, poultry, dairy, eggs, fish, soy, quinoa, hemp, chia seeds, amaranth, buckwheat, pistachios, and spirulina.

If you are vegan, you can get complete proteins through food combinations. Vegans can incorporate complementary proteins into their diet by eating a wide variety of whole grains, legumes, seeds, nuts, and veggies. This will help them get all their essential and nonessential amino acids. For example, oatmeal topped with nuts, ezekiel bread topped with nut butter, hummus, rice and beans, rice and lentils, and/or oatmeal for breakfast and beans for lunch. You do not need to get your complete proteins at one meal, just in the same day.

So, once we eat proteins, what does our body do with them?

  • 1
    Digestion of the proteins starts in the stomach with hydrochloric acid (HCL), which helps break down (or denature) the complex structure of the protein.
  • 2
    Partially digested proteins leave the stomach and enter the small intestine, where they are further broken down to smaller components, namely amino acids to be absorbed and transported to the blood and the tissues.
  • 3
    The liver processes the amino acids before they are sent out to the body tissues.
  • 4
    The amino acids will be broken down to further create urea or ammonia, excreted by the kidneys, and will also be used to create glucose and fatty acids. We cannot store excess protein, so the body needs to convert it to glucose and fatty acids for later use or excrete it.

Recommended Daily Intake of Protein

There are different stages in our lives when we require more or less protein, such as during pregnancy, under stress, ill, training for a competition (protein builds muscle), or even seasonally throughout the year. However, the average protein intake for many Americans is 15-20% of daily calories. For a person who requires a 2,000 calorie per day diet, that’s about 75 grams of protein. The Institute of Medicine recommends that adults get a minimum of 0.8 grams of protein for every kilogram of weight per day.

Protein is one of the most satiating macronutrients—it can help curb your appetite and those nasty sugar cravings. It is helpful to consume proteins if you are trying to lose weight, maintain blood sugar, fight metabolic issues, manage symptoms of adrenal fatigue, or if you are under a tremendous amount of stress.