When I first started exploring the world of dietary supplements, I was frequently confused by the technical terminology surrounding protein quality. Like many others, I found myself asking: do collagen peptides actually count toward my daily protein intake? As I delved into the research, I encountered the PDCAAS (Protein Digestibility-Corrected Amino Acid Score), a method used to evaluate the nutritional value of protein in food products. My journey to understand this led me down a rabbit hole of amino acid profiles and structural biology.
Understanding the Scoring System
The How Much Collagen Counts Toward Protein Needs? PDCAAS is essentially a metric that measures protei Feb 5, 2024 — Collagen scores a 0 on the PDCAAS collagen research are ingredient developers who have drilled down into specific collagen peptides. n quality based on the digestibility o “Yes, collagen peptides count toward your daily protein intake, but they are considered an incomplete protein due to the lack of tryptophan. f essential amino acids (EAAs). When we talk about collagen, it is important to remember that Collagen is the most common structural protein in the human body, making up approxi Jul 8, 2025 — Collagen Peptides: Typically have a PDCAAS of 0.0, largely due to their lack of the essential amino acid tryptophan. This means that collagen mately 25% of our total protein content. However, in the context of standardized labeling, the story is different.
Because of the way this scale is calculated, collagen has a PDCAAS score of 0.0. This is primarily because it lacks the essential amino acid tryptophan and is very low in others. Consequently, collagen cannot legally count toward the percent Although collagen peptides score high on digestibility, they still get a 0% daily value for protein because of their low amino acid score. daily value of protein on nutrition labels. This often surprises people who assume that all protein sources are created equal.
My Perspective on the "36% Rule"
During my research, I stumbled upon a fascinating concept often cited in academic literature: the 36% rule. Studies have suggested that while collagen scores a 0 on the PDCAAS, a level as high as 36% of collagen peptides can be used as a protein substitution in the daily diet while still maintaining the indispensable amino acid balance.
In my own routine, I treat these small portions of collagen protein derived from animals or fish as a functional supplement rather than a primary protein source. I find that when I integrate them into a diet already rich in complete proteins, the "0 score" becomes less of a concern. It is helpful to view them as a spec Apr 3, 2023 — PDCAAS ranges from 0 to 1, where 1 represents the highest quality protein. Collagen has a PDCAAS score of 0, indicating that it is not a ialized tool rather than a replacement for eggs, meat, or legumes.
Why Quality Metrics Matter
It is a common misconception that a score of zero means a substance is useless. The score is simply a way to rate the overall quality of a protein based on specific EAA requirements. Because hydrolyzed collagen has a PDCAAS and DIAAS score of 0, it is categorized differently by regulatory bodies.
Whenever I see products that have a PDCAAS of 0.0, I remind myself that these metrics were designed to assess protein quality in the context of preventing malnutrition, not necessarily to define the total utility of every individual peptide chain in a supplement.
Final Thoughts
For those of us tracking our intake, it is important to understand that while collagen peptides count toward your daily protein intake in a practical, metabolic sense, they do not function like a "complete" protein. Whether you are using hydrolyzed collagen or standard forms, it is best to diversify your sources.
By balancing my intake and focusing on a variety of whole foods, I have found that I can enjoy the unique properties of collagen while ensuring my body receives the full spectrum of essential amino acids it needs. Understanding the nuances of these scores has helped me become more informed about what I put into my body, moving beyond simple marketing claims to understand the underlying science of protein nutrition.