Everybody wants a complete protein, yet many people don’t really understand what the phrase “complete protein” actually means. 

Collagen is the most abundant protein in the body. Its fiber-like structure is used to make connective tissue. Collagen protein supplements have become one of the most popular supplements on the market today. However, the majority of collagen products on the market are not a complete protein. So, what makes a protein a “complete protein?” 

It has to do with the amino acid makeup of the protein. A protein must have 9 essential amino acids that your body does not produce on its own to be considered a complete protein.1 In fact, only protein from animal sources contain the 9 essential amino acids found in a complete protein.

I’m going to tell you about the nine essential amino acids found in a complete protein, why collagen supplements are not complete proteins, and the one collagen protein on the market that is as close to a complete protein as you can find. First, I’m going to tell you what an amino acid actually is. 

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What is an Amino Acid?

Remember when you were a kid playing with building blocks? Amino acids are technically building blocks that build proteins, hormones and neurotransmitters. 

The protein in your food is broken down into amino acids during the digestion process. These amino acids are then sent to the areas that need them. Amino acids are used by your body for various functions such as ​​tissue repair, digestion, muscle building, boosting your immune system response, and providing cells with energy. 2

Amino acids are made up of nitrogen, carbon, hydrogen, and oxygen. To function properly, your body needs 20 different amino acids. However, only 9 amino acids are classified as essential amino acids – leucine, histidine, methionine, isoleucine, lysine, phenylalanine, threonine, tryptophan, and valine. I’ll discuss the 9 essential amino acids in more detail later. 

The other 11 amino acids are known as nonessential, however, some are known as conditional amino acids. You might be asking what’s the difference between the three groups of amino acids. Well, I’m going to tell you! 

The 3 Groups of Amino Acids

As I mentioned before, there are 20 amino acids that fall into two main categories – essential and nonessential amino acids. The difference is that your body can make nonessential amino acids. Essential amino acids only come from food, primarily animal sources. 

In some cases, such as pregnancy, suffering an injury, or chronic stress, your body cannot produce a handful of nonessential amino acids on its own. These amino acids are known as conditionally essential amino acids. Let’s take a closer look at the groups of amino acids. 

Essential Amino Acids

Essential amino acids must come from food. You can only get them from animal sources, as I mentioned earlier. Foods high in essential amino acids include grass-fed beef, free-range chicken, wild-caught seafood, eggs and cow’s dairy.3 Here are the 9 essential amino acids: 

  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine

Since you can only get all nine amino acids from animal sources, it’s critical to eat a diet rich in grass-fed beef, free-range chicken, and while-caught seafood. Let’s go deeper into what these essential amino acids do in your body and what foods they are found in. 

The 9 Essential Acids Required In A Complete protein – Infographic – Amy Myers MD®The 9 Essential Acids Required In A Complete protein - Infographic - Amy Myers MD® https://content.amymyersmd.com/article/is-collagen-a-complete-protein/The 9 Essential Acids Required In A Complete protein – Infographic – Amy Myers MD®

The Functions of the 9 Essential Amino Acids

You can’t have a complete protein without all nine amino acids. A lot of collagen and protein supplements on the market have very few, if any, essential amino acids. While plant proteins contain some of the essential amino acids, they do not contain all of them. As I said before, the only way to get all 9 essential amino acids is from food. However, some people have sensitivities to some of the foods containing essential amino acids such as legumes, soy, eggs, and dairy which makes it more difficult. I’ll talk more about that in just a second. Here’s what each of the 9 essential amino acids do:


Histidine supports the growth and repair of damaged tissues, the formation of blood cells, and protecting nerve cells.. It also is used to make histamine, which is important for immunity, digestion, and reproductive health. Histidine is found in grass-fed beef, wild-caught fish, poultry, nuts, seeds and whole grains. 


Isoleucine regulates energy levels and facilitates wound healing, supports your immune system, helps promote healthy blood glucose levels, and supports hormone production. It is found in grass-fed beef, wild-caught fish, poultry, eggs, cheese, lentils, nuts, and seeds. 


Leucine plays a vital role in wound healing and the production of growth hormone. It also helps regulate blood sugar levels and aids the growth and repair of muscle and bone. Leucine is found in soy, beans, and legumes. 


Lysine is one of the amino acids used to build collagen.4

It supports muscle building, bone strength, and promotes hormone production, immune system function, and the formation of digestive enzymes. Lysine is found in grass-fed beef, eggs, soy, legumes, and pumpkin seeds. 


Methionine supports healthy hair, skin, and nails. While collagen provides structure to your hair, skin, and nails, methionine is not part of the amino acid profile of collagen.5 It is also not found in most collagen supplements. Methionine is found in eggs, grains, nuts, and seeds. 


Phenylalanine is an amino acid that is modified during the digestive process to make tyrosine, an important nonessential amino acid that supports brain function and facilitates the production of important brain hormones such as endorphins, oxytocin, and dopamine.6 It is found in grass-fed beef, poultry, soy, wild-caught fish, legumes, and nuts. 


Threonine is needed to create glycine and serine, two nonessential amino acids that are necessary for the production of collagen, elastin, and muscle tissue. Threonine facilitates muscle elasticity and strength, including your heart, where it is abundant. The issue is that threonine is mostly found in dairy products such as cottage cheese, some legumes, and eggs. Dairy, legumes, and eggs can trigger autoimmune symptoms. I often recommend eliminating these foods when following The Myers Way® or other autoimmune protocol diets. 


Tryptophan does more than facilitate the release of melatonin, which your body produces to promote sleep.7 It also is needed to produce serotonin, a neurotransmitter involved in sleep, appetite, inflammation, and your mood. Serotonin helps regulate cortisol levels when your body is under stress. Tryptophan is cow’s milk, tuna, turkey, free-range chicken, oats, cheese, nuts, and seeds. 


Valine promotes muscle growth and tissue repair. It’s essential for mental focus, muscle coordination, and brain health. Valine is found in grass-fed beef, wild-caught seafood, soy, and dairy. 

As you can see, these 9 essential nutrients live up to their name because they are, in fact, essential to many of your body’s processes. Remember, your body does not make these essential amino acids on their own. The only way to get them is through your diet. 

Unfortunately, a lot of the foods that contain essential amino acids are problematic for a lot of people. Gluten, dairy, soy, eggs and legumes are inflammatory foods. If you’re unsure as to what foods you have a sensitivity to, I recommend following an elimination diet and reintroducing foods one by one and track your symptoms. 

Gluten and dairy are the top two most inflammatory foods. I don’t recommend adding them back into your diet, particularly if you have an autoimmune or thyroid condition or want to prevent these conditions.

Nonessential Amino Acids

Despite their name, nonessential amino acids are very important to many of your body’s natural processes. However, your body makes these on their own. When your body breaks down carbohydrates to make energy, your cells also create nonessential amino acids. 

Some nonessential amino acids can only be formed by modifying another amino acid, which your cells also do behind the scenes. You can also get nonessential amino acids directly from your diet. The nonessential amino acids include: 

  • Alanine
  • Arginine
  • Asparagine
  • Aspartic acid
  • Cysteine
  • Glutamic acid
  • Glutamine
  • Glycine
  • Proline
  • Serine
  • Tyrosine

Glycine, proline, arginine, and hydroxyproline (which is made from proline), are the nonessential amino acids found in collagen. 

Glycine is the main amino acid in collagen.8 It’s made by modifying the amino acids serine, hydroxyproline, and threonine.9 Proline, arginine, and hydroxyproline also make up collagen’s cellular structure, yet to a lesser degree. Vitamin C supports the process of converting these amino acids into collagen protein.10

Conditional Amino Acids

Conditional amino acids are typically nonessential, however if you suffered an injury, have a chronic illness, under stress, or are pregnant your body cannot make them on their own. In these cases, it’s important to get enough protein in your diet or through a supplement. 

Conditional amino acids include: arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine.

Remember, glycine is the most abundant amino acid in collagen and it is made from serine. Proline and arginine are also two amino acids found in collagen. If you have chronic illness, or under stress, or have an injury, you need to supplement collagen

Is Collagen a Complete Protein?

The short answer is no, collagen is not a complete protein. Collagen contains 19 amino acids, however the one missing is tryptophan, one of the essential 9 amino acids that make up a complete protein. So by definition, collagen is not a complete protein. 

Some collagen supplements may have fortified tryptophan in them, however this requires heavy processing of amino acids, which are very fragile. During processing, amino acids could break apart and generate toxins. You’re better off getting tryptophan from food. 

Some collagen supplements may contain fortified tryptophan in them. This requires heavy processing of amino acids, which are very fragile. During processing, amino acids could break apart and generate toxins. You’re better off getting tryptophan from food. 

Collagen has a very specific job in your body. It provides strength and elasticity to skin and provides structure and supports our muscles, tendons, bones, and blood vessels. Think of collagen as the “glue” that holds your body together.

Your body naturally produces collagen, yet your body cannot produce the 9 essential amino acids that make up a complete protein. The four amino acids found in collagen include glycine, proline, alanine, and hydroxyproline, all of which are classified as nonessential amino acids. The truth is that most collagen supplements do not have many of the 9 essential amino acids. Don’t worry, I’m going to tell you about a collagen protein supplement that contains 8 of the 9 essential amino acids, making it as close to a complete protein as you can find. 

Why You Need to Supplement Collagen

Your body produces collagen on its own, however at about age 35, your body slows down production of collagen. By age 40, collagen begins to deplete faster than your body can produce it. What’s more, over half of your body’s collagen has been depleted by the age of 60. This rapid decline is why it’s important to know what to look for in a high-quality collagen supplement. 

What if I told you can find a collagen protein supplement that contains 19 of the 20 amino acids your body needs, including 8 of the 9 essential amino acids. 

Collagen Protein is the closest to a complete protein that you’ll find in a collagen supplement. Collagen Protein contains the nonessential amino acids found in abundance in collagen, along with eight of the nine essential amino acids your body needs. Now, it comes in a convenient capsule form.

Whenever I don’t have time to make a smoothie or mix collagen powder in my coffee on a busy  morning, Collagen Protein capsules provide me a convenient way to ensure I’m getting optimal amounts of collagen each day. 

Collagen Protein capsules contain the same high-quality hydrolyzed collagen as Collagen Protein powder in a convenient capsule. It is sourced from 100% grass-fed, pasture-raised bovine collagen to support a healthy gut lining and intestinal permeability, promote vibrant hair, skin, and nails, and facilitates healthy bones and joints. 

While collagen is not considered a complete protein, Collagen Protein contains 19 of the 20 amino acids your body needs without sacrificing quality. If you want a full-range high quality collagen with essential and nonessential amino acids in a convenient capsule, then Collagen Protein capsules are perfect for you. 

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Article Sources

  1. Do I Need to Worry About Eating Complete Proteins?. Cleveland Clinic. 2019.
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  3. What to know about essential amino acids. Natalie Olsen, RD, LD. Medical News Today. 2019.
  4. 13 Foods That Help Your Body Produce Collagen. Sarah Garone. Healthline. 2019.
  5. Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance. Sarah Garone. Nutrients, vol 11. 2019.
  6. Tyrosine: Fact Sheets. . Mount Sinai Health System. 2021.
  7. Tryptophan. Mallorie Stallings. Sleep. 2021.
  8. Top 9 Benefits and Uses of Glycine. Gavin Van De Walle, MS, RD. Healthline. 2018.
  9. Top 9 Benefits and Uses of Glycine. Gavin Van De Walle, MS, RD. Healthline. 2018.
  10. Collagen Synthesis. Dr. Ananya Madal, MD. News Medical Life Sciences. 2019.