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Protein: Part 2 What Are The Different Sources Of Protein?

Updated: Mar 30, 2023

Hopefully you have had a chance over the last couple of weeks to dive into Protein: Part 1. In that post I covered:
  • Why protein is so important, how it functions in the body, and why it would be problematic to not be consuming enough

  • How much protein we really need

  • Other considerations that would drive up our overall protein need

Now that you have an idea of your general protein need, I want to dive into the sources of protein and how those are different.

Proteins are more complex and have much more variety in structure than do carbohydrates or lipids. Most proteins are made up of tens to thousands of 20 common amino acids, which allows for an infinite number of combinations. These 20 amino acids are divided into two categories:

  • 9 are considered essential, meaning that we cannot physically make them ourselves and that we must get them through food.

  • The other 11 are considered nonessential since our body has the ability to produce them itself, so it may not be necessary to regularly consume these amino acids from the diet.

A food source that's a complete protein is one that contains all 9 essential amino acids, while an incomplete protein does not. All animal-based foods are complete proteins and a much more nutrient-dense way of eating than plant-based protein.

Most plant proteins sources including grains, legumes, nuts, and seeds are missing adequate quantities of one of more of the essential amino acids. And generally speaking, protein from plants is not as concentrated or digestible as it is in animal foods. Plant protein is considered less bioavailable, because it's processed differently in the body. Plant proteins are wrapped up in fibers that inhibit the digestibility and they also contain anti-nutrients, compounds like lectins and oxalates, which are just the natural defense mechanisms built into plants to help them survive in nature. When we consume plants, we also eat the defense mechanisms and it's usually not a big deal. But these anti-nutrients can affect protein digestion and reduce amino acid absorption, meaning we are just not accessing the amino acids in the protein in the exact same way that we do from animals. Soy is the one plant exception to being a complete protein. Side note: 95% of all soy grown in the United States today is genetically modified, so I would always recommend buying organic if you are including soy in the diet. Additionally, the best sources of soy that keep the protein intact are going to be those that have been traditionally fermented, i.e., tempeh and miso.

  • Quinoa is also more complete than most other plant foods, although it still has limiting amino acids, so it is not sustainable for long term protein status alone.

I also understand that not everyone chooses to include animal foods in their diet for personal reasons. So, in the case of being a vegan and/or vegetarian, utilizing complimentary proteins is going to be extremely important. This means taking two completely different proteins and utilizing them together in the diet to make a “complete” protein. I'll show you an example of one keystone combination that includes combining legumes and grains. Four of the common limiting amino acids in plant foods include isoleucine, lysine, methionine, and trytophan.

  • Legumes contain isoleucine and lysine, but not methionine or tryptophan.

  • Grains contain methionine and tryptophan, but not isoleucine and lysine.

  • Together legumes and grains contain all the amino acids to be a complete protein source.

The downside to only utilizing complimentary plant sources without any animal sources is that it can be challenging for those with a compromised blood sugar balance, since it does necessitate a significantly higher carbohydrate intake in the diet.

  • Brown rice (½ cup) = 20 grams net carb, 2.5 grams protein (incomplete)

  • Black beans (½ cup) = 14 grams net carb, 6 grams protein (incomplete)

  • Complimentary = 34 grams net carb, 8.5 grams protein (complete)

  • 2 eggs = 1 grams net carb, 12 grams protein (complete)

  • Chicken breast (4 oz.) = 0 grams net carb, 35 grams protein (complete)

  • Wild salmon (4 oz.) = 0 grams net carb, 29 grams protein (complete)

Now for another few key tips…

It's important to rotate your sources of protein for the different amino acid profiles, to make sure you are getting a good variety of different proteins.

  • If you are a meat eater, that means going beyond your comfort zone of the same pack of chicken breasts. Utilize the benefits of turkey, pork, duck, elk, beef, bison, lamb, etc.

  • Seafood, fish, crustaceans (crab, lobster, and shrimp), and bivalves (clams, mussels, and oysters) are excellent sources of protein.

  • Eggs and dairy products like yogurt and cheese.

  • And even if you are not a vegan or vegetarian, it's also great to get in the habit of incorporating plant proteins into the diet as well. This includes whole grains, legumes, organic soy, nuts, and seeds.

Attempt to evenly distribute your protein intake throughout the day instead of eating > 60 grams in one sitting. It's best to evenly spread out your daily protein intake at each of your meals.

  • If you are eating an animal-based protein, aim for at least 4-6 oz. per meal. Another good rule of thumb is that the portion of protein is about the size of your palm.

  • If you are the type that loves starting your morning with a smoothie, then add 20 grams of protein powder to your blender.

Other ways to incorporate more protein throughout the day.

  • Add a variety of seeds like pumpkin seeds and hemp seeds to your morning bowl, toss into salads, or use as a topping for soups.

  • Incorporate nutritional yeast into a vegetable-based meal. 2 tablespoons will get you an additional 5 grams of protein.

  • Reach for animal jerky or a bag of lupini beans for a quick snack on the go. Lupini beans are a more recent addition to the market and they are gaining popularity due to the high amount of plant protein that they provide. 100 calories of lupini beans provides 12 grams of protein, vs. 4 grams in chickpeas or almonds.

  • Swapping regular cooking broth (1 gram of protein per cup) for bone broth (10 grams of protein per cup).

That's a wrap. I hope this two part series on protein has been helpful!

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