Hair thins as we age, and so does the scalp it grows from. Marine collagen is one of the simplest ways to support both. Two human trials found that collagen supplements led to measurably thicker hair strands and less shedding. That's why I think it belongs in a hair and skin routine, especially in midlife.

Why collagen matters for hair

A hair strand is made of keratin. The tissue that grows and holds each hair is a different story. Your scalp skin and the thin sheath wrapped around every follicle are built largely from collagen, and like facial skin, that tissue gets thinner with age. Supporting that collagen network helps support the environment your hair grows from.

Collagen peptides do more than turn into amino acids. In 2005, Koji Iwai's team in Japan gave volunteers collagen hydrolysate and found an intact two-amino-acid fragment, prolyl-hydroxyproline, circulating in their blood afterward. Later research suggests these fragments act as signals to fibroblasts, the cells that make collagen in the skin. Nearly every collagen supplement on the market is built on this finding.

Type I collagen: the one your hair and skin depend on

Your body makes more than two dozen types of collagen, but Type I does most of the work in skin. It makes up roughly 80% of the collagen in the dermis. It's the main structural protein of the scalp and of the connective-tissue sheath around each hair follicle, and it's what gives skin its firmness and resilience.

Marine collagen is almost entirely Type I. When you take it, you're getting the type your skin and scalp actually rely on, not a mix built around other tissues.

The human trials on hair

Thicker strands (Kiel, Germany). Forty-four women aged 39 to 75 took 2.5 grams a day of collagen peptides or a placebo for four months. The study was run by the Collagen Research Institute in Kiel. Strands in the collagen group got about 1.93 micrometers thicker on average. In the placebo group, they got about 0.99 micrometers thinner. The difference was statistically significant. When hair is fine, a few percent more thickness per strand across a whole head can be the difference between hair that looks limp and hair that holds a style.

Less shedding (Thailand, 2025). In a six-month randomized trial of menopausal women published in Clinics and Practice, women taking 5 grams of fish collagen a day shed less than the placebo group. Hair shed in a one-minute combing test fell from the mid-teens to about nine hairs by three months.

What the lab research shows

A Korean research group led by Tae-Gyu Lim tested a six-amino-acid fish collagen peptide on human dermal papilla cells. These are the cells at the base of each follicle that signal it to grow. Several growth factors tied to the hair cycle went up. When the same peptide was given to mice, they grew larger, denser follicles (Journal of Medicinal Food, 2025). This work helps explain how fish collagen peptides may support the follicle directly.

Why we add vitamin C

Your body can't build collagen without vitamin C. Two enzymes, prolyl hydroxylase and lysyl hydroxylase, need vitamin C to stabilize collagen's triple-helix structure. Without it, new collagen comes out weak and unstable. Vitamin C is also an antioxidant that helps protect existing collagen from oxidative stress. Putting it in the same scoop means the collagen peptides come with the cofactor your body needs to use them.

Why we add hyaluronic acid

Collagen gives skin its structure, and hyaluronic acid keeps that structure hydrated. HA holds water in the dermis, and it declines with age just as collagen does. Randomized trials of oral hyaluronic acid have shown improved skin moisture and fewer visible fine lines. Together, the two support the whole extracellular matrix: collagen for strength, HA for hydration. That includes the skin of the scalp.

Why wild-caught marine collagen

Marine vs. bovine. Bovine collagen comes from cow hide and is a mix of Type I and Type III. Marine collagen is concentrated Type I, the type most relevant to skin and the follicle sheath. Marine collagen is also typically hydrolyzed into low-molecular-weight peptides, which absorb efficiently. It contains no mammalian sources, which makes it suitable for pescatarians and for people who avoid beef.

Wild-caught vs. farmed. Much of the marine collagen on the market comes from farmed fish raised in crowded aquaculture, where feed additives and antibiotics are common. Wild-caught fish grow in their natural environment, without aquaculture drugs. Using their skin, which would otherwise be discarded, makes the most of every catch. For a supplement you take every day, a cleaner and more traceable source matters.

Who it's for

The person most likely to benefit is a woman or man in their 40s or 50s whose hair is getting finer or shedding a bit more, and who wants to support hair and skin quality from within. Her profile closely matches the women in both trials. Both trials ran at least 16 weeks, so I recommend taking it consistently for four to six months.

For pattern thinning, marine collagen works best alongside a topical treatment such as minoxidil, as part of a complete regimen.

Dose and safety

The human trials used 2.5 to 5 grams a day. Choose a product that tells you exactly how many grams of collagen are in each serving. In the trials, collagen was well tolerated. Because it comes from fish, anyone with a fish allergy should talk to their doctor first, as should anyone who is pregnant or breastfeeding.

Where MDhair fits

Our Marine Collagen ($48) combines wild-caught marine collagen peptides with hyaluronic acid and vitamin C to support hair, skin, nail, and joint health. It's also part of our Premium Regrowth Kit ($156), alongside topical treatment and other supplements.

My team and I ran a six-month clinical trial of MDhair's personalized regimen, published in the Journal of Drugs in Dermatology in 2025. We compared it with the leading hair loss supplement brand. At 90 days, hair growth had improved about 2.8 times as much, and hair quality about 3.0 times as much.

Not sure what your hair needs? Our free AI hair and scalp assessment starts with a short quiz and a scalp photo. Every regimen includes unlimited chat access to our dermatologist team.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. If you're pregnant, nursing, allergic to fish, or taking regular medication, check with your doctor before use.

Dr. Yoram Harth is a board-certified dermatologist and Co-Founder and Chief Medical Officer of MDalgorithms Inc., the company behind MDhair and MDacne. A magna cum laude graduate of Tel Aviv University's Sackler School of Medicine, he trained in dermatology at Rambam Medical Center and completed a research fellowship at Columbia-Presbyterian Medical Center in New York. His work spans phototherapy, photodynamic therapy, and AI-personalized skin and hair care.

Sources

1. Iwai K, et al. Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates. J Agric Food Chem. 2005;53(16):6531-6536.
2. GELITA AG. Increased hair thickness with Bioactive Collagen Peptides. Collagen Research Institute, Kiel. 2020.
3. Duangjai A, et al. Calcium and vitamin D supplementation with and without collagen in menopausal women: a randomized controlled study. Clin Pract. 2025;15(9):168.
4. Koo J, et al. Gly-Pro-Val-Gly-Pro-Ser low molecular weight fish collagen peptide promotes hair regeneration in human dermal papilla cells and C57BL/6 mice. J Med Food. 2025.
5. Bhardwaj V, Rodgers N, Harth O, Harth Y. Artificial intelligence-based personalization of treatment regimen for hair loss: a 6-month clinical trial. J Drugs Dermatol. 2025;24(3):233-238.

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