Walk into any pharmacy and you'll see two kinds of collagen: marine (from fish) and bovine (from cows). Both supply the same amino acid building blocks. But for skin specifically, the differences in molecular structure produce measurably different results.
The molecular reason marine collagen wins for skin
Skin is roughly 80% Type I collagen. Marine collagen is overwhelmingly Type I — the exact match. Bovine collagen is a mix of Type I and Type III. Type III is structurally different and is more abundant in organs and blood vessels than skin.
This means marine collagen peptides, when broken down by your gut, are more likely to be incorporated into skin tissue specifically — versus bovine, which gets distributed across more body systems.
Bioavailability — peptide size matters
Hydrolysed collagen (the only useful supplement form) is broken into smaller peptides for absorption. The size of these peptides is critical:
- Marine collagen peptides: Typically 2,000-5,000 Daltons
- Bovine collagen peptides: Typically 5,000-10,000 Daltons
Smaller peptides absorb more efficiently and reach skin tissue intact. Vida Glow's marine collagen, for example, uses a patented hydrolysation process producing 3,000-Dalton peptides — at the lower end of marine collagen's range, optimised for absorption.
Where bovine collagen still has the edge
For joints, gut barrier integrity, and overall connective tissue, bovine collagen Type II and Type III contribution can matter. SRW Skl¹, for instance, uses Type II collagen specifically for joint cartilage support — sourced from chicken sternum, which is even more Type-II-rich than bovine.
Practical takeaways
- Goal: skin glow, hair, nails → Marine collagen (Type I dominant)
- Goal: joint support, cartilage → Bovine or chicken Type II
- Goal: gut barrier → Either, but Type III specifically helps gut lining
- Halal/Kosher: Marine collagen is generally easier to certify (no slaughter requirements for fish)
What about peptide form?
Don't confuse "collagen peptides" with "collagen powder." All useful supplements are hydrolysed (broken down). "Gelatine" — the unhydrolysed form — is harder to absorb and not appropriate for daily supplementation.
How long until you see results?
- Marine, daily: Skin hydration shifts at 4-8 weeks. Elasticity at 12 weeks. Hair density at 3-6 months.
- Bovine, daily: Joint comfort changes at 8-12 weeks. Skin changes are typically slower than marine.
Frequently asked questions
Can I take both? Yes. Many users stack marine for skin and bovine (or chicken) for joints. They work on overlapping but distinct pathways.
Is one more environmentally sustainable? Marine collagen sourced from sustainably-managed fisheries (look for MSC-certified, wild-caught, or aquaculture-certified products) has a lower carbon footprint than bovine in most analyses.
Does it taste fishy? Quality marine collagen is virtually flavourless. Cheap brands sometimes have a residual fishy taste. Vida Glow's products are flavoured (mango, peach, blueberry) which masks any subtle taste.