Can I count my collagen as protein?

November 11, 2025 •

3 min read

Collagen, the most abundant protein in your body, makes up about 30% of its total protein content and is crucial for skin, bone, and connective tissue. This raises a common question for many health enthusiasts: can I count my collagen as protein to meet my daily nutritional requirements?

Quick Summary

Collagen is an incomplete protein missing the essential amino acid tryptophan, meaning it can't be a sole protein source. It contributes to total intake and supports connective tissue but needs to be complemented by other high-quality protein foods.

Key Points

Incomplete Protein: Collagen lacks the essential amino acid tryptophan, classifying it as an incomplete protein source.
Contributes to Total Intake: Despite being incomplete, the amino acids in collagen do contribute to your overall daily protein intake.
Not for Muscle Building: Collagen is a poor source for muscle protein synthesis compared to complete proteins like whey, which are rich in leucine.
Supports Connective Tissue: Its unique amino acid profile, high in glycine and proline, makes it beneficial for supporting skin, joint, and bone health.
PDCAAS of Zero: The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) for collagen is 0.0, indicating its low quality for meeting all essential amino acid needs.
Complementary Role: Collagen should be used to complement, not replace, a balanced diet that includes a variety of high-quality, complete protein sources.

Understanding the Building Blocks of Protein

To understand if you can count collagen as protein, it is vital to first differentiate between complete and incomplete protein sources. Proteins are composed of smaller units called amino acids. Of the 20 amino acids your body uses, nine are considered “essential,” meaning they cannot be synthesized by the body and must be obtained through your diet.

Complete proteins: Contain all nine essential amino acids in sufficient quantities. Animal products like meat, fish, eggs, and dairy, as well as plant-based sources like soy and quinoa, are examples of complete proteins.
Incomplete proteins: Lack or have very low levels of one or more of the nine essential amino acids. Most plant-based proteins fall into this category, but they can be combined to form a complete protein profile.

Why Collagen Is Considered an Incomplete Protein

Collagen is a unique protein primarily composed of the non-essential amino acids glycine, proline, and hydroxyproline. While it contains eight of the nine essential amino acids, it is critically deficient in the essential amino acid tryptophan. Because it is missing a key building block, collagen is classified as an incomplete protein.

The nutritional quality of a protein is often measured by the Protein Digestibility-Corrected Amino Acid Score (PDCAAS), which assesses a protein’s amino acid profile and digestibility. Complete proteins typically score a 1.0, the highest possible value. Because of its tryptophan deficiency, hydrolyzed collagen is assigned a PDCAAS of 0.0, indicating its low nutritional quality for meeting all essential amino acid needs. This is why you will see collagen supplements list a certain number of grams of protein, but often with a footnote stating that it does not contribute to the Percent Daily Value (%DV) for protein.

Comparing Protein Sources: Collagen vs. Whey vs. Plant-Based

To highlight the nutritional differences, let's compare collagen with two other popular protein sources: whey and plant-based protein.


Feature	Collagen	Whey Protein	Plant-Based Protein (e.g., Pea & Rice)
Amino Acid Profile	Incomplete, lacks tryptophan. High in glycine, proline, hydroxyproline.	Complete, contains all 9 essential amino acids. Rich in BCAAs, especially leucine.	Often incomplete individually, but combinations like pea and rice can form a complete profile.
Best For	Supporting connective tissue, skin, hair, and joint health.	Muscle protein synthesis, strength, and recovery.	Vegan/vegetarian diets, promotes satiety.
PDCAAS	0.0.	1.0.	Varies by source, but often lower than whey. Pea protein is around 0.89.
Muscle Building	Less effective due to lower leucine content and incomplete profile.	Highly effective due to high leucine content.	Can be effective, especially when combining sources for a complete profile.
Absorption	Readily digested and absorbed as peptides.	Quickly digested and absorbed, especially post-workout.	Digestion speed varies by source.

How to Use Collagen Effectively for Your Protein Needs

While collagen cannot serve as your sole protein source, it can be a valuable supplement. The key is to use it as a complementary protein, not a replacement for high-quality, complete sources. Studies suggest that collagen peptides can make up a significant portion of your total protein intake (up to 36% in one study) as long as the rest of your diet provides sufficient essential amino acids.

Practical ways to incorporate collagen:

Combine with tryptophan-rich foods: Add collagen powder to a shake that includes milk, which contains ample tryptophan. Mix it into yogurt with seeds or nuts for a similar effect.
Use it strategically: Take collagen to target its specific benefits for connective tissue. Some research suggests taking it before a workout may support joints.
Include diverse protein sources: Ensure your diet includes a variety of complete protein sources throughout the day, such as lean meats, eggs, fish, dairy, and soy products.

A list of complete protein food sources:

Lean meat (beef, pork, lamb)
Poultry (chicken, turkey)
Fish and seafood (salmon, tuna, shrimp)
Eggs
Dairy products (milk, cheese, yogurt)
Soy products (tofu, tempeh, edamame)
Quinoa
Buckwheat

Conclusion: So, can I count my collagen as protein?

The answer is yes, you can count the amino acids from collagen towards your total daily protein intake, but with important caveats. Because collagen is an incomplete protein that lacks the essential amino acid tryptophan, it cannot be your only or primary source of protein, particularly for building and repairing muscle tissue. It excels at supporting connective tissues like joints, skin, and bones due to its unique amino acid profile. For optimal health, use collagen as a supplement to complement a varied diet rich in high-quality, complete protein sources.

Frequently Asked Questions

No, collagen is an incomplete protein because it lacks the essential amino acid tryptophan. While it does provide other amino acids, it cannot be considered a complete source of protein on its own.

Yes, you can count the grams of protein from collagen towards your daily intake. However, due to its incomplete amino acid profile, it should be considered a complementary source, not a primary one.

Collagen is not an ideal protein for muscle building. It lacks the amino acid leucine, which is a key trigger for muscle protein synthesis. High-quality complete proteins like whey are more effective for this purpose.

To make collagen a complete protein, you must combine it with a source that provides the missing tryptophan. This can be achieved by mixing it with other foods like milk or by consuming a diverse diet rich in complete protein sources.

The best approach is to consume a variety of high-quality protein sources throughout the day, such as lean meats, dairy, eggs, soy, and legumes, in addition to your collagen supplement. This ensures you get a complete and balanced amino acid profile.

The primary benefits of collagen relate to supporting connective tissue. It has been shown to improve skin elasticity and hydration, support joint function and health, and promote stronger hair and nails.

The choice depends on your goals. For muscle building and maximum protein synthesis, whey protein is superior. For targeted support of skin, joints, and connective tissue, collagen is more effective. Many people choose to supplement with both for combined benefits.