Collagen Protein Vs Whey Protein: Key Differences

📌 Overview and Key Takeaways

This is a Dietitian’s perspective on collagen protein vs whey protein.

Discover the key differences so you can decide which one is right for you.

Last Updated
Feb 2, 2026

Author and Medical Reviewer

Written by Kayla Kamen, MS, RD

Kayla Kamen is a Registered Dietitian with a MS in Nutrition.

Medically reviewed by Jennifer Fossett, PA-C

Jennifer Fossett is a Physician Assistant with a BA in Nutritional Sciences.

Whey Protein vs Collagen Protein

What Is Collagen?

Collagen is a type of protein found in the skin, bones, and connective tissues of animals.

It is also the most abundant protein in humans, accounting for about 30% of our body’s total protein.

Most collagen protein supplements are made from bovine (cow) or marine (fish) collagen peptides.

Collagen peptides have undergone hydrolysis, a process that breaks down the protein into smaller pieces that are easier to digest and absorb.

What is Whey?

Whey is a liquid byproduct of cheese and yogurt making.

It has two main components: protein and lactose (sugar).

There are two types of whey protein supplements: whey protein concentrate (70-80% protein) and whey protein isolate (90% protein).

Collagen vs Whey Protein

There are several methods used to determine the quality of a dietary protein in human nutrition.

The preferred method is the protein digestibility corrected amino acid score (PDCAAS), which takes into account amino acid composition and digestibility.

• Amino Acid Composition: Amino acids are the building blocks of protein. There are 20 of them in the human body, 9 of which are essential, meaning we must get them from food. A dietary protein source that contains all 9 essential amino acids is considered a complete protein. The PDCAAS considers how much of each essential amino acid is in a dietary protein, and compares those values to the reference pattern established by the Food and Agriculture Organization of the United Nations, which represents the ideal amino acid profile for human nutrition.
• Protein Digestibility: The PDCAAS also accounts for the digestibility of a dietary protein, as not all dietary proteins are digested and absorbed by the body in the same way. Dietary proteins that are more easily digested and absorbed have a higher PDCAAS.

Whey protein has a PDCAAS of 100, which is the highest score possible (J Sports Sci Med, 2004).

Not only does it contain high amounts of all the essential amino acids, but it is also easily digested and absorbed by the body.

Collagen protein, on the other hand, has a PDCAAS of 0 because it lacks one essential amino acid, tryptophan.

This does not mean that collagen is not a good source of protein, however, it is simply a reminder that the PDCAAS is an imperfect method of assessment.

The PDCAAs is biased towards a protein’s “completeness,” and ignores its nutritional value as part of an overall diet.

Research shows that including collagen peptides at up to 36% of total daily dietary protein intake maintains an overall PDCAAS of 100 (Nutrients, 2019).

In other words, as long as you are getting your dietary protein intake from a variety of sources, collagen is as good a protein source as any.

The idea that whey is better than collagen, or any other dietary protein source for that matter, is thus misleading.

Whey does have the highest PDCAAS possible, but that is not an advantage for someone eating a balanced diet.

In fact, 99% of people meet 100% of their essential amino acid needs without supplements (J Nutr, 2023).

Moreover, the PDCAAS of your dietary protein intake should not exceed 100 – fulfill more than 100% of your essential amino acid requirements – because your metabolic needs include both essential and non-essential amino acids.

If one or more essential amino acids were present in excess, your diet would become limited in essential amino acids, and thus unbalanced even though the PDCAAS remains equal to 100.

In short, as long as you are eating a balanced diet – getting protein from a variety of sources – the benefits of adding whey protein to your diet versus collagen are minimal.

It is worth adding that because it is a derivative of milk, whey protein is not suitable for people with lactose intolerance.

If you are lactose intolerant – two thirds of adults are – consuming whey protein can cause digestive issues like bloating and diarrhea.

Collagen protein, on the contrary, is super easy on the stomach.

Order Samples to see for yourself.

Sources

1. Journal of Sports Science & Medicine (J Sports Sci Med). Protein – Which is Best?. 2004.
2. Nutrients (Nutrients). Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance. 2019.
3. The Journal of Nutrition (J Nutr). Amino Acid Intake and Conformance With the Dietary Reference Intakes in the United States: Analysis of the National Health and Nutrition Examination Survey, 2001-2018.. 2023.

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This article was written by a Registered Dietitian and reviewed by a Physician Assistant. We rely on peer-reviewed research and trusted medical sources, and regularly update our content to ensure accuracy and clarity.