Collagen and Skin, Hair and Nails: What the Research Says

The Short Answer: Collagen is the main structural protein of the dermis, and the body's own production falls by an estimated 1 to 1.5 per cent a year from the mid-twenties (Reilly and Lozano, 2021). This article sets out the biology: what collagen is, why production declines, what happens to hydrolysed peptides after you drink them, and which of the individual nutrients in the shot relate to skin, hair and nails.

What is collagen?

Collagen is a structural protein, and the main one in the dermis, the layer of skin beneath the surface. Its molecules form a triple helix, those helices assemble into fibrils, and fibrils bundle into fibres, producing a dense connected network through the dermis. Type I is the dominant type in that network, and is 80 to 90 per cent of skin collagen (Reilly and Lozano, 2021).

That is what collagen is. What happens to it when you drink it is a separate question, and the next sections take it in order.

Why does collagen production decline with age?

Production begins to decline from the mid-twenties, at an estimated 1 to 1.5 per cent a year (Reilly and Lozano, 2021). After menopause the rate accelerates to an average of 2.1 per cent per postmenopausal year over a 15 year period, driven largely by the fall in oestrogen (Viscomi et al., 2025).

Cumulative figures for the proportion of collagen lost by a given age are quoted constantly and none of them come from a measurement. The annual rate is the sourced part. The arithmetic built on top of it is not.

Read more: Collagen After 30: Why Your Skin Needs More Than Skincare

The mechanisms are reasonably well described. Fibroblasts, the dermal cells that synthesise collagen, become less active with age. The enzymes that break collagen down, the matrix metalloproteinases, become more active. Oestrogen deficiency after menopause is associated with reduced collagen production and a weakened extracellular matrix, which in turn compromises the structural support of dermal fibroblasts and accelerates their decline (Viscomi et al., 2025). The receptor involved is oestrogen receptor beta, which the same review describes as the predominant receptor subtype in skin. Oral collagen does not restore oestrogen.

What happens to collagen peptides after you take them?

Hydrolysed collagen has already been broken into shorter peptide chains before you drink it (Leon-Lopez et al., 2019). Digestion continues that process, and low-molecular-weight peptides are absorbed into the bloodstream after oral intake. Virgilio et al. (2024) demonstrated this directly, tracking collagen-derived peptides appearing in plasma after a hydrolysate drink. That study was funded by Rousselot, a collagen manufacturer.

Collagen is unusually high in glycine, proline and hydroxyproline, and those amino acids become available to the body after absorption. That is the mechanism, and it is as far as the evidence takes it. A mechanism is a description of a pathway, not a measurement of an outcome, and this category conflates the two constantly.

Which nutrients relate to skin, hair and nails

When a pack tells you its collagen firms, plumps, smooths or strengthens, the useful question is what that sentence is attached to. On a supplement label, a line about skin, hair or nails belongs to a specific nutrient at a specific dose, and it should be traceable to one. A sentence hung on the collagen itself, with no nutrient and no dose behind it, is doing marketing work rather than telling you anything.

Aura is marine collagen plus 12 actives. These are the lines, and the nutrients they belong to.

Skin: Vitamin A, biotin and zinc each contribute to the maintenance of normal skin. Vitamin C contributes to normal collagen formation for the normal function of skin.

Hair: Biotin, selenium and zinc each contribute to the maintenance of normal hair.

Nails: Selenium and zinc each contribute to the maintenance of normal nails.

Read those three lines closely, because the detail catches almost everyone out. Biotin belongs with skin and hair, not with nails. Selenium belongs with hair and nails, not with skin. The familiar sentence about biotin, zinc and selenium supporting skin, hair and nails, which you will find right across this category, therefore puts two of them in the wrong place. Vitamin A belongs with skin, and it is the one most brands leave out entirely.

Read more: What Is in Aura? Every Ingredient Explained

What role does Vitamin C play?

Vitamin C is not part of the collagen molecule, but it is a required cofactor in collagen synthesis. Prolyl hydroxylase and lysyl hydroxylase, the enzymes that hydroxylate collagen's amino acids and allow the triple helix to stabilise, depend on it. Without adequate vitamin C that step does not proceed properly, however much collagen protein is available. Pullar et al. (2017) reviewed the range of vitamin C's roles in skin.

The wording is precise, and the precision is the point: vitamin C contributes to normal collagen formation for the normal function of skin. Note where that line attaches. It belongs to vitamin C, not to a product and not to the marine collagen in the shot. Aura carries 120mg of vitamin C alongside 15,000mg of hydrolysed marine collagen, which is why the two sit together.

People Also Ask

How long before I see something? Nobody can give you a date. The timelines in circulation are lifted from how long the trials ran, most of them manufacturer-funded, and then repeated as though they were a rule about people rather than a decision about study design. A supplement is taken consistently or it is not taken at all.

Read more: How Long Does Collagen Take to Work?

Can I get collagen from food instead of a supplement? Bone broth, gelatin and skin-on meat all contain collagen. The practical difference is that the amount varies from batch to batch and is generally well below a supplement serving, whereas a measured dose is measured. That is a point about dose consistency, not about one being better absorbed than the other.

Why does collagen decline faster after menopause? Falling oestrogen is associated with reduced collagen production and a weakened extracellular matrix, which leaves dermal fibroblasts less well supported. The rate of loss accelerates from roughly 1 to 1.5 per cent a year to an average of 2.1 per cent per postmenopausal year over a 15 year period (Viscomi et al., 2025).

Read more: 15,000mg Marine Collagen: Does Dose Actually Matter?

Key Takeaway: Collagen is the main structural protein of the dermis, and the body's own production falls from the mid-twenties, faster after menopause. Hydrolysed collagen is absorbed as low-molecular-weight peptides after oral intake. Past that point, be careful who you believe. The lines about skin, hair and nails belong to specific nutrients, not to the collagen. Vitamin A, biotin and zinc each contribute to the maintenance of normal skin. Biotin, selenium and zinc each contribute to the maintenance of normal hair. Selenium and zinc each contribute to the maintenance of normal nails. Vitamin C contributes to normal collagen formation for the normal function of skin.

References

Reilly, D.M. & Lozano, J. (2021). "Skin Collagen Through the Lifestages: Importance for Skin Health and Beauty." Plastic and Aesthetic Research, 8, 2. DOI: 10.20517/2347-9264.2020.153. Both authors work for Minerva Research Labs, which produces collagen-based supplements.

Viscomi, B., Muniz, M. & Sattler, S. (2025). "Managing Menopausal Skin Changes: A Narrative Review of Skin Quality Changes, Their Aesthetic Impact, and the Actual Role of Hormone Replacement Therapy in Improvement." Journal of Cosmetic Dermatology, 24(Suppl 4), e70393. DOI: 10.1111/jocd.70393. PMC12374573

Leon-Lopez, A. et al. (2019). "Hydrolyzed Collagen: Sources and Applications." Molecules, 24(22), 4031. PMC6891674

Virgilio, N. et al. (2024). "Absorption of Bioactive Peptides Following Collagen Hydrolysate Intake: A Randomized, Double-Blind Crossover Study in Healthy Individuals." Frontiers in Nutrition, 11, 1416643. PMC11325589. Funded by Rousselot BV.

Pullar, J.M. et al. (2017). "The Roles of Vitamin C in Skin Health." Nutrients, 9(8), 866. PMC5579659