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 PDCAAS is essentially a metric that measures protein quality based on the digestibility of 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 approximately 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 a 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 nd is very low in others. Consequently, collagen cannot legally count toward the percent 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 functio May 27, 2025 — Collagen is the most common structural protein in the human body, making up about 25% of the body's total protein content. nal 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 specialized 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 Do Collagen Peptides Count as Protein? The 36% Rule & 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 desi (PDF) Significant Amounts of Functional Collagen Peptides gned to assess protein quality in the context of preventing malnutrition, not Does Collagen Powder Count Towards Protein Intake? 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 p by SM Phillips · 2023 · Cited by 3 — Hydrolyzed collagen has a PDCAAS and DIAAS score of 0 since it contains no tryptophan (Trp) and is very low in methionine (8). The author apologizes for this ractical, 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.