Our previous article on marine vs. bovine collagen, raised a question worth exploring further: if Type I collagen content explains part of marine collagen's reputation for skin support, what explains the rest? We think the answer lies in peptide size and it's worth a proper deep dive.
Collagen does not travel directly from a scoop in a glass to smoother skin. It is first broken down in the gut into peptide fragments before being absorbed into circulation. Some of those peptides then appear to interact with fibroblasts in the dermis, the cells responsible for producing collagen, elastin, and hyaluronic acid. The size of those peptides may influence how efficiently that process happens.
Why Hydrolysis Matters
In its natural form, collagen is a large structural protein not designed to move easily through the digestive tract (1). Hydrolysis breaks it down with enzymes into much smaller fragments, reducing molecular weight and making the peptides easier to absorb.
The peptide size produced during hydrolysis depends heavily on the collagen source and processing method. Low molecular weight collagen peptides are generally considered smaller hydrolysed collagen fragments, often discussed within the 1,000 to 5,000 dalton range in research and commercial formulations (2). Marine collagen is frequently processed into relatively small peptide fragments, while some bovine collagen products are produced with larger average molecular weights. During digestion, these peptides are further broken down into smaller di- and tripeptides that can enter circulation (4).
How Peptide Size Affects Absorption
Most dietary protein is absorbed as individual amino acids, the smallest possible building blocks. Collagen behaves a little differently. Some collagen-derived fragments survive digestion intact and are actively transported across the gut wall by a protein called PEPT1 (5).
Think of PEPT1 as a dedicated doorway in the small intestine for small peptides. It recognises short collagen fragments, particularly those containing hydroxyproline, an amino acid found almost exclusively in collagen, and shuttles them directly into the bloodstream. One fragment in particular, Pro-Hyp, consistently appears in human blood after collagen ingestion and typically reaches peak levels within one to two hours (6).
Smaller peptides are generally considered more favourable for intestinal transport than larger collagen fragments (3), which is why the size difference between marine and bovine collagen is more than a technical detail. Well-hydrolysed marine collagen is thought to allow more bioactive peptide fragments to enter circulation.
How Collagen Peptides Signal the Dermis
Once in the bloodstream, collagen peptides do not simply become new collagen fibres. Human studies suggest oral collagen peptides can support skin hydration and markers of the dermal collagen network, while ex vivo research helps explain how these effects may occur (7).
Fragments like Pro-Hyp and Hyp-Gly appear to act as signalling molecules for fibroblasts within the dermis. Research suggests they appear to stimulate collagen repair while also slowing some of the enzymes involved in collagen breakdown (8).
Vitamin C also matters. Fibroblasts require it to properly stabilise newly formed collagen fibres, which is why collagen is often paired with vitamin C-rich foods or supplements (11).
Together, these mechanisms help explain why marine collagen research tends to show gradual improvements in hydration, elasticity, and wrinkle appearance over time.
Read more in our previous collagen articles:
What Human Studies Actually Show
In a randomised, placebo-controlled study, participants taking 1,000 mg of low molecular weight fish collagen peptides daily for 12 weeks showed measurable improvements in skin hydration, elasticity, and wrinkle depth compared with placebo (9). Reductions were also observed in the enzymes responsible for collagen breakdown, suggesting marine collagen appears to influence both collagen production and collagen breakdown.
A separate trial found similar improvements in wrinkle scores and elasticity after 12 weeks in women aged 45 to 60 (10).
Hydration improvements tend to appear first, often within 4 to 8 weeks. Structural changes take longer, with most studies running 8 to 12 weeks at doses of 2.5 to 10 g daily. Augment Life Marine Collagen is hydrolysed to around 2,000 daltons and is typically taken once daily, dissolving easily into coffee, smoothies, yoghurt, or water.
The Takeaway
Much of marine collagen research now focuses on what happens after digestion. Hydrolysis creates smaller peptides, some of which survive digestion intact and enter circulation. These peptides may help support fibroblast activity, dermal collagen structure, and skin hydration, although the exact mechanisms are still being studied.
Marine collagen appears to work less like a cosmetic intervention and more like nutritional support for the skin’s existing repair processes. The research is strongest around hydration, elasticity, and wrinkle appearance, particularly with consistent intake over several weeks. The effects are gradual, which makes sense given that collagen turnover in skin is naturally slow.
Read more about collagen in our other articles: Marine Collagen vs. Bovine Collagen: What Is The Best Collagen For You? How to take collagen?
Literature Sources
- Kadler KE, et al. “Collagens at a Glance.” Journal of Cell Science. 2007;120(12):1955–1958. DOI: 10.1242/jcs.03453
- Choi E, et al. “Low-Molecular-Weight Collagen Peptide Improves Skin Dehydration and Barrier Dysfunction.” International Journal of Molecular Sciences. 2025;26(13):6427. DOI: 10.3390/ijms26136427
- Larder CE, Iskandar MM, Kubow S. “Assessment of Bioavailability After In Vitro Digestion and First Pass Metabolism of Bioactive Peptides From Collagen Hydrolysates.” Current Issues in Molecular Biology. 2021;43(3):1592–1605. DOI: 10.3390/cimb43030113
- Virgilio N, Schön C, Mödinger Y, van der Steen B, Vleminckx S, van Holthoon FL, Kleinnijenhuis AJ, Silva CIF, Prawitt J. “Absorption of Bioactive Peptides Following Collagen Hydrolysate Intake: A Randomized, Double-Blind Crossover Study in Healthy Individuals.” Frontiers in Nutrition. 2024;11:1416643. DOI: 10.3389/fnut.2024.1416643
- Herrera-Ruiz D, Knipp GT. “Current Perspectives on Mammalian Oligopeptide Transporters.” Journal of Pharmaceutical Sciences. 2003;92(4):691–714. DOI: 10.1002/jps.10303
- Ohara H, et al. “Hydroxyproline-Containing Peptides in Human Blood After Oral Ingestion of Gelatin Hydrolysates.” Journal of Agricultural and Food Chemistry. 2007;55(4):1532–1535. DOI: 10.1021/jf062834s.
- Asserin J, Lati E, Shioya T, Prawitt J. “The Effect of Oral Collagen Peptide Supplementation on Skin Moisture and the Dermal Collagen Network: Evidence From an Ex Vivo Model and Randomised, Placebo-Controlled Clinical Trials.” Journal of Cosmetic Dermatology. 2015;14(4):291–301. DOI: 10.1111/jocd.12174
- Jimi S, Sato K. “Collagen-Derived Dipeptide Pro-Hyp as a Growth-Initiating Factor for Fibroblasts.” Frontiers in Cell and Developmental Biology. 2020;8:548975. DOI: 10.3389/fcell.2020.548975
- Kim DU, et al. “Oral Intake of Low Molecular Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling.” Nutrients. 2018;10(7):826. DOI: 10.3390/nu10070826
- Evans M, et al. “Efficacy of a Freshwater Marine Collagen on Skin Wrinkles and Elasticity.” Journal of Cosmetic Dermatology. 2021;20(3):825–834. DOI: 10.1111/jocd.13676
- Murad S, et al. “Regulation of Collagen Synthesis by Ascorbic Acid.” PNAS. 1981;78(5):2879–2882. DOI: 10.1073/pnas.78.5.2879
