Vital Proteins Collagen Peptides, the brand’s flagship product, contains types I and III collagen derived from bovine hide. These two types account for the vast majority of collagen in the human body, and they show up together in skin, tendons, bones, and blood vessels. The product is hydrolyzed, meaning the collagen proteins have been broken down into smaller peptides that dissolve in liquid and are easier for the gut to absorb. But knowing the label says “types I and III” only scratches the surface of what that means for your body and whether the distinction actually matters once you drink it.
What Types I and III Actually Do
Your body makes at least 28 different types of collagen, but types I and III do the heavy lifting in most of the tissues you care about when you think of “collagen supplements.” Type I is the most abundant protein in the entire body. It forms the dense, rope-like fibers that give tensile strength to skin, bones, tendons, and ligaments. Think of it as the structural steel in a building: stiff, strong, and resistant to being pulled apart.1PubMed Central. A Comprehensive Review on Collagen Type I Development of Biomaterials for Tissue Engineering: From Biosynthesis to Bioscaffold
Type III is more like the flexible cables in that same building. It forms an elastic network that allows tissues to stretch and snap back. You find it wherever your body needs to balance rigidity with give: the walls of blood vessels, the lining of the intestines, the skin, and the uterus.2PubMed Central. Regulation of Collagen I and Collagen III in Tissue Injury and Regeneration Type III is also heavily involved in wound healing, where it gets laid down first as a kind of scaffolding before type I gradually replaces it during tissue remodeling.
The two types do not simply coexist side by side. Type III typically forms mixed fibers with type I, creating a composite structure that is both strong and flexible.3Frontiers in Bioengineering and Biotechnology. The role of collagen and collagen I/III ratio in pathological conditions: insights into molecular mechanisms and therapeutic approaches Research in mice lacking the gene for type III collagen found that without it, type I fibers formed abnormally in the cardiovascular system and other organs, leading to fatal aortic rupture early in life.4PubMed Central. Type III collagen is crucial for collagen I fibrillogenesis and for normal cardiovascular development In humans, mutations in the gene for type III collagen are linked to a connective-tissue disorder that causes fragile blood vessels. The takeaway is that type III is not a minor sidekick; it is essential for type I to assemble correctly.
Why Bovine Collagen Naturally Contains Both Types
You might wonder whether a supplement manufacturer blends types I and III together, but that is not quite what happens. Bovine hide and bone are tissues where types I and III are already intertwined. When collagen is extracted from cowhide using acid and enzymatic methods, both types come along for the ride because they are physically woven into the same fibers.3Frontiers in Bioengineering and Biotechnology. The role of collagen and collagen I/III ratio in pathological conditions: insights into molecular mechanisms and therapeutic approaches The ratio between them shifts depending on the source tissue and the animal’s age, but the pairing is a natural feature of mammalian connective tissue, not a formulation choice.
Marine collagen, by contrast, is sourced mainly from fish skin and scales. It is overwhelmingly type I, with very little type III.5Collagen and Leather. A review on marine collagen: sources, extraction methods, colloids properties, and food applications This is one reason bovine collagen dominates the types-I-and-III supplement market while marine collagen gets marketed primarily as a type I product. If getting both types matters to you, bovine-sourced products like Vital Proteins are the more straightforward option.
What Happens After You Swallow Collagen Peptides
Here is where the “types I and III” label gets complicated in a way that most marketing glosses over. Hydrolyzed collagen has already been broken into small peptide chains, typically in the range of a few thousand daltons.6PubMed Central. Hydrolyzed Collagen-Sources and Applications Your digestive enzymes then chop those peptides even further into individual amino acids and tiny di- and tripeptides, especially fragments containing hydroxyproline, which is an amino acid almost unique to collagen.
These small peptides can cross the intestinal wall intact. Research on brush-border enzymes shows that hydroxyproline-containing dipeptides and tripeptides are transported through intestinal cells by a specific peptide transporter, meaning they enter the bloodstream as recognizable collagen fragments rather than just loose amino acids.7Food Research International. Production of collagen-derived hydroxyproline (Hyp)-containing di- and tripeptides by brush border membrane enzymes and their absorption characteristics This matters because those peptide fragments appear to act as signaling molecules, nudging your own cells to ramp up collagen production rather than simply serving as raw building materials.
The practical implication is that once collagen is fully digested into these small peptides, the “type I versus type III” distinction largely dissolves. The peptides circulating in your blood are not labeled with a type anymore. They are short amino acid sequences, many of them shared across collagen types, that your cells use as both raw material and a biochemical signal to produce new collagen. Your body decides what type of collagen to build based on which tissue needs it, not based on which type you swallowed. This does not make the supplement useless; it just means the mechanism is less literal than “eat type I, get type I.”
Evidence for Skin Benefits
Skin is the tissue with the most clinical research behind collagen supplementation, and the results are generally positive. A systematic review and meta-analysis of hydrolyzed collagen studies found that taking it for about 90 days improved skin hydration, elasticity, and wrinkle appearance compared to placebo.8PubMed. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis A separate review that pooled findings from multiple trials reached similar conclusions, noting improvements in moisture and elasticity with no reported side effects from oral collagen supplements.9PubMed Central. Collagen Supplements for Aging and Wrinkles: A Paradigm Shift in the Fields of Dermatology and Cosmetics
An animal study on chronologically aged mice helps illustrate one possible mechanism. Mice given collagen peptides from bovine bone showed improved skin laxity, increased collagen content, and a normalized ratio of type I to type III collagen in their skin, suggesting the supplements influenced not just the amount but the composition of skin collagen.10PubMed Central. Effect of Orally Administered Collagen Peptides from Bovine Bone on Skin Aging in Chronologically Aged Mice That I-to-III ratio shifts with age, with older skin tending to lose the organized balance between the two types, so restoring it is an encouraging sign even if we should be cautious about extrapolating mouse data directly to humans.
Lab studies on human skin cells add another layer. When cultured dermal fibroblasts were treated with collagen peptides, the cells increased expression of the gene responsible for making type I collagen and also boosted expression of genes for elastin and versican, a molecule that helps skin retain water.11PubMed Central. Collagen peptides affect collagen synthesis and the expression of collagen, elastin, and versican genes in cultured human dermal fibroblasts A separate cell study found that collagen peptides combined with other bioactive compounds stimulated fibroblast proliferation, meaning the cells multiplied more readily.12Scientific Reports. Effects of collagen-derived bioactive peptides and natural antioxidant compounds on proliferation and matrix protein synthesis by cultured normal human dermal fibroblasts These are promising results, though cell-culture findings do not automatically translate to visible changes in a person’s face.
Joint and Bone Support
Beyond skin, types I and III collagen are major structural components of cartilage borders, tendons, ligaments, and bone matrix, so it makes sense to ask whether supplementation helps those tissues too. A systematic review of type I collagen hydrolysate studies reported that the majority of trials evaluating joint health found beneficial outcomes, including reductions in joint pain, improved physical mobility, and better ankle function.13PubMed Central. The Effects of Type I Collagen Hydrolysate Supplementation on Bones, Muscles, and Joints: A Systematic Review
A double-blind, placebo-controlled trial specifically tested a combination of type I, type III, and type II collagen peptides in people with knee osteoarthritis. After eight weeks of supplementation, participants showed significant improvements in pain scores, quality-of-life measures, balance, and walking distance compared to placebo.14PubMed Central. Effect of supplementation with type 1 and type 3 collagen peptide and type 2 hydrolyzed collagen on osteoarthritis-related pain, quality of life, and physical function: A double-blind, randomized, placebo-controlled study That trial used a multi-type blend, so it is hard to isolate the contribution of types I and III alone, but it does suggest these collagen types play a role in joint comfort.
For bones, a meta-analysis found that collagen peptide supplementation significantly increased bone mineral density in the femoral neck and spine, though results varied quite a bit across trials. The same analysis also showed improvements in bone-turnover markers and modest gains in muscle performance, especially when collagen was paired with vitamin D and calcium.15PubMed Central. Efficacy of collagen peptide supplementation on bone and muscle health: a meta-analysis The variability across studies is worth noting: some trials showed large effects and others modest ones, likely reflecting differences in dosing, duration, and the populations studied.
The Amino Acid Profile and Why Cofactors Matter
One thing that sets collagen apart from other protein supplements is its amino acid composition. Glycine, proline, and hydroxyproline together make up roughly 57% of collagen’s total amino acids.16PubMed. Roles of dietary glycine, proline, and hydroxyproline in collagen synthesis and animal growth This gives collagen a very different profile from whey or plant-based protein powders, which are higher in branched-chain amino acids and lower in glycine. Collagen is not a complete protein in the traditional sense; it is essentially missing tryptophan and is low in several other essential amino acids. That makes it a poor sole protein source but a potentially useful targeted supplement for connective tissue.
Your body cannot build new collagen without certain cofactors. Vitamin C is the most well-known one: it is required for the enzymes that add hydroxyl groups to proline and lysine residues, a step without which collagen chains cannot fold into their characteristic triple-helix shape. Vital Proteins adds a small amount of vitamin C to some of its formulations for this reason.
Copper is another often-overlooked cofactor. The enzyme lysyl oxidase, which creates the cross-links that give collagen and elastin fibers their mechanical strength, depends on copper to function. Research has shown that the synthesis of mature, fully cross-linked collagen and elastin is directly controlled by copper availability.17PubMed. Copper and the synthesis of elastin and collagen Most people get enough copper from foods like nuts, shellfish, and organ meats, but a severely copper-deficient diet could theoretically limit how much benefit you get from a collagen supplement. Zinc and iron also play supporting roles in collagen metabolism, which is why a generally nutrient-rich diet matters more than any single supplement.
Emerging Research on Gut Health
An area gaining attention is whether collagen peptides support the intestinal lining. This makes intuitive sense because type III collagen is a major structural component of the gut wall, and the intestinal epithelium turns over rapidly. Early research, mostly from cell and animal models, suggests there may be something to it.
A study on collagen peptides and their breakdown products found that they protected intestinal cells against oxidative damage by activating a cellular stress-response pathway. The peptides were protective against chronic colitis in mice, and the mechanism appeared to involve strengthening the gut lining’s defenses against oxidative stress through multiple biochemical routes.18PubMed. Collagen Peptides Ameliorate Murine Chronic Colitis: Toward the Molecular Basis for Their Enhancement of Intestinal Epithelial Defenses Against Oxidative Stress A separate study using marine-derived collagen peptides in a mouse model of ulcerative colitis reported that oral supplementation reduced intestinal permeability by about 38%, improved colon tissue appearance, and rebalanced inflammatory markers.19PubMed Central. Marine Collagen Peptide Fraction from Lutjanus erythropterus Scales: A Multifunctional Bioactive for Intestinal Barrier Protection and Redox Modulation in Ulcerative Colitis
This is still early-stage science. Mouse models of colitis do not map neatly onto the human experience of inflammatory bowel disease or everyday digestive complaints. But the findings are consistent enough across different collagen sources and models that the gut-health angle is worth watching. If you have been told that collagen “heals your gut lining,” the honest picture is that the idea has biological plausibility and some animal support, but rigorous human trials are still sparse.
Safety and Contaminant Concerns
Collagen supplements have a strong safety profile in the clinical literature. The systematic reviews on skin and joint outcomes generally report no significant adverse effects from oral hydrolyzed collagen, even at doses of 10 to 15 grams per day taken for months.9PubMed Central. Collagen Supplements for Aging and Wrinkles: A Paradigm Shift in the Fields of Dermatology and Cosmetics The most common complaints are mild digestive symptoms like bloating or a lingering taste.
Because collagen is sourced from animal tissues, questions about heavy-metal and antibiotic contamination come up. A study that tested commercial collagen products for lead, mercury, arsenic, cadmium, and several antibiotics found no lead, mercury, or arsenic residues in any sample. Cadmium and zinc were detected at low levels, and antibiotic residues were either absent or below detection limits.20Veterinary Journal of Mehmet Akif Ersoy University. Investigation of Possible Heavy Metals and Antibiotic Residues in Commercial Collagen That said, the supplement industry is lightly regulated compared to pharmaceuticals. Third-party testing certifications (NSF, USP, Informed Sport) provide an extra layer of confidence when they are present on a product’s label.
Type II Collagen and the Labeling Confusion
If you have shopped for collagen supplements, you have probably noticed that some products are marketed as type II collagen, usually aimed at joint health. Type II collagen is the dominant collagen in hyaline cartilage, the smooth, glassy tissue that cushions your joints. It is structurally different from types I and III and is typically sourced from chicken sternum cartilage rather than bovine hide.
Undenatured type II collagen (often labeled UC-II) works through a different proposed mechanism than hydrolyzed types I and III. It is taken at very low doses, usually around 40 milligrams, and is thought to modulate the immune system’s response to cartilage rather than providing raw building material. The types-I-and-III products like Vital Proteins, on the other hand, are taken at much higher doses (10-20 grams) and work by supplying collagen-specific amino acids and signaling peptides.
The two approaches are not interchangeable. If your primary concern is joint cartilage and you have osteoarthritis, some evidence supports UC-II specifically for that purpose. If you are looking for broader connective-tissue support that spans skin, hair, nails, tendons, and bones, a hydrolyzed types-I-and-III product makes more sense. Some supplements, like the one tested in the osteoarthritis trial mentioned earlier, combine all three types.14PubMed Central. Effect of supplementation with type 1 and type 3 collagen peptide and type 2 hydrolyzed collagen on osteoarthritis-related pain, quality of life, and physical function: A double-blind, randomized, placebo-controlled study The point is that “type” on a collagen label is not just a marketing gimmick; it reflects real differences in source tissue, mechanism, and intended use.
Sustainability and Sourcing Trends
Bovine collagen is extracted from hides and bones that are byproducts of the meat industry. From a waste-reduction standpoint, turning these materials into supplements is a form of upcycling. Researchers have been exploring ways to make the extraction process greener, including the use of natural deep eutectic solvents to dissolve and repurpose collagen-rich waste from the leather industry, turning what would be discarded into functional biomaterials.21PubMed Central. From Waste to Function: Valorization of Collagen-Based Wastes with Natural Deep Eutectic Solvents for Bioadhesive Applications
Marine collagen has gained popularity partly because of perceived sustainability advantages and partly because it avoids concerns related to bovine spongiform encephalopathy, though modern sourcing and testing have made that risk extremely low. Fish skin and scales, like bovine hides, are largely processing waste. The collagen yield from fish, jellyfish, and sea cucumbers tends to be high, and the product is predominantly type I.5Collagen and Leather. A review on marine collagen: sources, extraction methods, colloids properties, and food applications For people who avoid beef for religious, dietary, or environmental reasons, marine collagen is a viable alternative, though it means forgoing the type III component that comes naturally with bovine sources. Whether that trade-off matters depends on what you are trying to achieve and how much weight you give to a mechanism that, as noted earlier, largely dissolves once digestion breaks the collagen into its constituent peptides.