Not All Collagen Is the Same: Types, Sources, and Why It Matters for Your Health

Collagen is the most abundant protein in the human body, accounting for roughly 30% of total protein mass. It forms the structural backbone of skin, bone, cartilage, tendons, ligaments, and the gut lining. As we age, collagen synthesis declines — measurably so after the mid-20s — and the downstream effects show up as joint degradation, reduced skin elasticity, slower recovery, and compromised gut integrity.

The supplement market has responded with an enormous range of collagen products. But the category has a problem: most consumers — and frankly, many brands — treat collagen as a single, uniform substance. It isn't. There are at least 28 distinct types of collagen identified in the scientific literature, each with different molecular structures, tissue distributions, and functional roles. The source of that collagen — what animal tissue it comes from and how it's processed — determines which types you're getting, in what proportions, and how bioavailable they actually are.

This post breaks down the three most clinically relevant collagen types, explains where they come from in conventional supplement products, and makes the case for why source and processing matter far more than the label claim.

The Three Collagen Types That Matter Most

Type I Collagen: The Most Abundant, and the Most Misrepresented

Type I collagen is the dominant structural collagen in the body. It's found in skin, tendons, bone, the cornea, and most connective tissue. In terms of sheer abundance, it dwarfs every other collagen type — approximately 90% of the body's total collagen is Type I.

Because of this, Type I is the most commonly marketed collagen in the supplement industry. It's associated with skin elasticity, wound healing, bone density support, and tendon integrity. These associations are broadly supported by the research literature, though the quality of evidence varies considerably by application.

The critical question — one that most products avoid entirely — is where that Type I collagen comes from. We'll address this in detail below, because the sourcing of Type I collagen is one of the most significant and underreported issues in the supplement industry.

Type II Collagen: The Joint Collagen

Type II collagen is the primary structural protein of articular cartilage — the smooth, load-bearing tissue that covers the ends of bones at synovial joints. Unlike Type I, which forms tight, parallel fibril bundles optimized for tensile strength, Type II collagen forms a looser, more hydrated fibril network that gives cartilage its compressive resilience and shock-absorbing capacity.

Type II collagen is also the primary antigen involved in rheumatoid arthritis. Research into oral tolerance mechanisms — the process by which the immune system is trained not to attack self-tissue — has shown that low-dose oral Type II collagen can modulate autoimmune responses in joint tissue. This is a distinct mechanism from the structural support provided by hydrolyzed collagen peptides, and it's why the form and dose of Type II collagen matters significantly in a clinical context.

Type II is predominantly sourced from cartilage — specifically from the sternal cartilage of chickens or the articular cartilage of bovine joints. It is not meaningfully present in skin or hide. Any product claiming to deliver significant Type II collagen from a hide-based source is making a claim that doesn't hold up to scrutiny.

Type III Collagen: The Companion Protein

Type III collagen is closely associated with Type I in most tissues. It's particularly concentrated in blood vessels, the gut wall, skin, and the uterus — tissues that require both structural integrity and a degree of elasticity. Type III forms reticular fibers, a fine meshwork that provides scaffolding for soft organs and vascular structures.

In the skin, Type I and Type III collagen exist in a roughly 4:1 ratio. In the gut lining, Type III plays a significant role in maintaining barrier integrity — a fact that has attracted growing research interest given the prevalence of intestinal permeability issues in modern populations.

Type III collagen is present in significant quantities in bone and the connective tissue surrounding it, making bone-derived collagen sources naturally rich in both Type I and Type III.

The Sourcing Problem: Where Most Collagen Actually Comes From

Here is the part of the collagen conversation that the industry actively avoids.

Tannery Hides and the Type I Collagen Supply Chain

The majority of Type I collagen on the supplement market — including many of the most recognizable and heavily marketed brands — is derived from bovine hides. Specifically, from the byproduct stream of the leather tanning industry.

Tanning is an industrial chemical process. Raw hides are treated with a range of agents — including chromium salts, aldehydes, and a variety of surfactants and biocides — to prevent decomposition and convert the skin into durable leather. The hide collagen extracted for supplement use comes from this same industrial supply chain, processed and hydrolyzed downstream of the tannery.

Manufacturers will point out that the collagen is purified after extraction, and that's true to a degree. But the starting material is an industrial byproduct of one of the more chemically intensive manufacturing processes in existence. For consumers who are trying to minimize their exposure to industrial chemicals, or who are choosing supplements specifically because they want clean, traceable inputs, this is not a trivial consideration.

It also raises a more basic question: if you have access to collagen sourced directly from bones, joints, and cartilage — the tissues where collagen is functionally most concentrated and nutritionally most relevant — why would you choose a hide-derived alternative?

Marine Collagen: A Cleaner Type I Source, With Limitations

Marine collagen — typically derived from fish skin and scales — has grown significantly in popularity as an alternative to bovine hide collagen. It is predominantly Type I and has a relatively high bioavailability due to its smaller peptide size. For consumers specifically seeking Type I for skin and wound-healing applications, marine collagen is a meaningfully cleaner source than tannery hides.

Its limitation is scope: marine collagen does not deliver Type II in any meaningful quantity, and its Type III content is limited. For musculoskeletal support — joints, cartilage, tendons — it is not the most targeted choice.

The Protein Quality Problem: PDCAAS and What Brands Don't Tell You

This is a technical point, but an important one for anyone evaluating collagen supplements on the basis of their protein content claims.

Protein quality is assessed using a metric called the PDCAAS — the Protein Digestibility Corrected Amino Acid Score. It measures how well a protein source delivers all essential amino acids relative to human requirements, adjusted for digestibility. A score of 1.0 is the maximum, indicating a complete protein that meets all essential amino acid requirements.

Collagen — regardless of source — is low in several essential amino acids and is notably deficient in tryptophan, one of the nine essential amino acids. Tryptophan is a precursor to serotonin and melatonin and cannot be synthesized by the body. A protein source with zero tryptophan has a PDCAAS of effectively zero, meaning it does not qualify as a complete protein by conventional nutritional standards.

Despite this, many leading collagen brands label their products with protein content figures that do not reflect the PDCAAS-adjusted value. A product that lists 10g of protein per serving based on nitrogen content alone, without disclosing that its PDCAAS score disqualifies it from contributing meaningfully to essential amino acid requirements, is presenting an incomplete picture to the consumer. Regulatory enforcement of this distinction has historically been inconsistent.

Our bone broth is produced from meaty bones — bones with residual meat tissue still attached. This matters because the meat fraction contributes a broader amino acid profile, including trace amounts of tryptophan, which most pure collagen products entirely lack. It doesn't make our product a complete protein in the conventional sense — we're not claiming that — but it does make it a more complete collagen source than hide-derived alternatives, and it's a distinction worth understanding.

Farmalogical's Collagen: A Natural Complex of Types I, II, and III

Our bone broth is produced from grass-fed, grass-finished New Zealand beef — specifically from meaty bones, joints, and articular cartilage. Because of this, the collagen it contains reflects the natural tissue distribution of collagen in the animal:

• Type II as the predominant collagen, sourced from articular cartilage and joint tissue
• Type I from bone collagen and the connective tissue of meaty bones
• Type III naturally present alongside Type I in bone and surrounding connective tissue

We describe this as a collagen complex that supports the three predominant collagen types found in the human body — in proportions that reflect how they occur naturally in the source tissue, rather than an artificially isolated or reconstituted blend.

This is not a marketing distinction. The tissue you source collagen from determines which types are present. Bone and cartilage deliver a genuinely different collagen profile than hide. The processing method — in our case, freeze-drying and cryomilling at -60°C for up to 97% nutrient retention — ensures that the bioactive peptides and native collagen structures are preserved through to the final product.

If you're evaluating a collagen supplement, the most important questions to ask are not on the front of the label. They're: What tissue did this come from? What was the source animal's diet and living conditions? How was it processed? The answers to those questions tell you far more than a gram count ever will.

Next in this series: Our organ meat blend — what's in it, where it comes from, and the specific nutrients each organ provides that whole-food diets rarely deliver in adequate quantities.