Collagen for Hair and Nails: What Has Been Measured

Collagen has been measured for nails and not for hair. In an open-label study of 25 people, 2.5 g of collagen peptides a day for 24 weeks increased the nail growth rate by 12% and cut the frequency of broken nails by 42%; there was no placebo group. No randomised trial has tested collagen on its own with hair growth or shedding as its main outcome.¹ Hair is keratin, not collagen; the collagen that matters to it is the collagen the body builds around the follicle. Shedding has common causes a GP can check, and the NHS sets the baseline: losing 50 to 100 hairs a day is normal.⁶ This page sits beneath the Wellgard collagen guide.

Does collagen help nails?

One study has measured it directly. In 2017, 25 people with brittle nails took 2.5 g of bovine collagen peptides once a day for 24 weeks, then stopped for four weeks. A physician measured growth rate, broken nails and overall improvement. Growth rate rose by 12% and the frequency of broken nails fell by 42%; 64% were judged improved overall, 88% were still improved four weeks after stopping, and 80% agreed their nails looked better.¹

The design limits what those numbers can carry. It was open-label and single-centre, with no placebo group, and the peptides came from a manufacturer. The results describe what happened to those 25 people, not what collagen did against chance or expectation. Collagen itself carries no authorised health claim in Great Britain, a statement about the register rather than a verdict on the study; the authorised nail wording, for a product that qualifies, is "Zinc contributes to the maintenance of normal nails".¹¹

A second trial touched nails as a side measure. In 2024, 85 healthy women aged 43 to 65 were randomised to 5 g of collagen peptides or 5 g of maltodextrin placebo for 84 days, with skin as the main question. Nail colour improved in the collagen group within 28 days; the placebo group showed the same change only at 84 days.² Colour is not strength or growth, so this is a controlled signal that nails respond, not the missing controlled growth trial.

How long before nails change?

The study measured at 24 weeks, so the published figures are six-month figures.¹ Nails are the one tissue you can watch yourself, as new nail grows out from the base. What you can notice after taking collagen puts nails alongside the skin, joint and bone timelines.

Does collagen help hair growth?

Hair is keratin: the strand is a dead keratin fibre, and swallowed collagen does not become it. Where collagen matters is the follicle, which makes the strand. Follicles sit in the dermis, which is largely collagen, and their stem cells depend on a collagen of their own, type XVII. A 2016 study in mice and human scalp samples found that as follicles age, their stem cells break down type XVII collagen, the follicle shrinks and hair thins; keeping that collagen in place in mice held the process back.³ That is collagen the body makes in the follicle; no study has tested whether eating collagen peptides changes it.

Two human trials come close. In a 2026 randomised, placebo-controlled trial, 114 women aged 20 to 50 with thigh cellulite and self-reported hair thinning took 1,000 mg a day of low-molecular-weight fish collagen peptides or placebo for 24 weeks. The trial measured cellulite severity, skin roughness and elasticity alongside hair shaft diameter, which increased significantly at week 24 in the collagen group.⁴ That is a controlled hair measurement at a 1 g dose, one endpoint among several, run by the ingredient's maker.

The other trial is not collagen evidence on its own. In 2023, 83 people with pattern hair loss or chronic telogen effluvium, all on a hair-loss medicine chosen by their clinician, were randomised to add a daily tablet of 300 mg fish collagen with taurine, cysteine, methionine, iron and selenium, or not. After 12 weeks a blinded assessor's photographic score was 1.67 with the tablet against 0.66 without.⁵ Six ingredients, a medicine underneath, the maker running the study: nothing in it isolates collagen.

What we do not know is whether collagen peptides taken alone change hair growth or shedding, because no trial has asked that first. What we do know is that the one controlled hair-diameter measurement went in collagen's favour.

Why is my hair falling out?

The NHS hair-loss page starts with the baseline: "It's normal to lose hair. We can lose between 50 and 100 hairs a day, often without noticing." Hair loss "is not usually anything to be worried about, but occasionally it can be a sign of a medical condition." Some types are permanent, "like male and female pattern baldness", which "usually runs in the family". Others "may be temporary" and "can be caused by: an illness, stress, cancer treatment, weight loss, iron deficiency." The advice is one line: see a GP "if you're worried about your hair loss". On recovery: "Hair loss caused by a medical condition usually stops or grows back once you've recovered."⁶

The temporary pattern has a name and a delay. Telogen effluvium is the commonest cause of diffuse shedding, and it appears three to four months after the trigger, so autumn handfuls can trace back to a summer illness, weight crash or shock. More shed hairs do not tell you the cause; that takes a history and, where needed, blood tests to rule out endocrine, nutritional and autoimmune causes.⁷ Hair loss on Mounjaro covers the fast-weight-loss version.

Two checkable causes sit on NHS symptom lists. Iron deficiency anaemia lists "hair loss, you notice more hair coming out when brushing or washing it" among its less common symptoms, and is "often because of blood loss or pregnancy".⁸ An underactive thyroid lists "dry skin, dry hair or hair loss"; an overactive one lists "patchy hair loss or thinning".^{9, 10} Patchy loss, scarring, soreness or shedding that does not settle are reasons to see a GP, who can order the blood tests and check your medicines.

Shedding after having a baby follows the same telogen pattern, a few months after the birth. The NHS hair-loss rule applies, that temporary hair loss grows back, with a GP if you are worried.⁶ Collagen in pregnancy and breastfeeding covers that time.

Biotin or collagen for thinning hair?

They are different kinds of answer. Collagen is a protein with one controlled hair-diameter measurement, one endpoint among several, and no trial of its own for hair.⁴ Biotin is a B vitamin with an authorised wording: "Biotin contributes to the maintenance of normal hair", for a food that supplies enough to qualify.¹¹ That describes biotin's role in normal hair, not growth; the measured improvements on biotin were in people who were short of it, and high doses distort common blood tests, thyroid tests included. Is biotin good for hair growth has the evidence and the blood-test rule. The NHS says biotin is needed "in very small amounts", that a varied and balanced diet should supply it, and that "taking 0.9mg or less a day of biotin in supplements is unlikely to cause any harm."¹²

Zinc and copper carry the other wordings: "Zinc contributes to the maintenance of normal hair" and "to the maintenance of normal nails"; "Copper contributes to normal hair pigmentation".¹¹ The NHS puts daily needs at about 9.5 mg of zinc for men, 7 mg for women and 1.2 mg of copper, and says not to exceed 25 mg of zinc a day unless a doctor advises it, because high zinc intakes reduce copper absorption.¹³ None of these wordings transfers to collagen; a collagen product that also contains biotin or zinc at a qualifying level may carry that nutrient's wording. What to take with collagen goes through the co-nutrients.

Which collagen is best for hair and nails?

No trial has compared collagen sources on a hair or nail result. The nail study used bovine peptides at 2.5 g; the hair-diameter measurement came from fish peptides at 1 g; the combination tablet used 300 mg of fish collagen.^{1, 4, 5} Bovine, porcine and marine peptides have each produced positive trials and none has been shown to outperform another, so "best for hair" has no evidence behind it as a type. What the studies give you is dose and duration: 2.5 g for 24 weeks for nails, 1 g for 24 weeks for the hair measurement, against the 2.5 to 15 g range used across collagen trials. Men will find the muscle, tendon and hair evidence in collagen for men.

Frequently asked questions

Will taking collagen make my nails stronger?

The measured result: in 25 people taking 2.5 g a day for 24 weeks, broken nails fell by 42% and growth rate rose by 12%, with no placebo group.¹ That is a result, not a promise.

Can collagen stop grey hair?

No trial has tested collagen on hair colour. The only authorised wording here is copper's: "Copper contributes to normal hair pigmentation".¹¹

Does collagen help hair loss on Mounjaro or after fast weight loss?

Weight loss is on the NHS list of causes of temporary hair loss, and the shedding appears three to four months after the trigger.^{6, 7} No trial has tested collagen for it. Does Mounjaro cause hair loss? covers it.

Is marine or bovine collagen better for hair?

Neither has been tested against the other for hair. The hair-diameter measurement used fish peptides at 1 g; the nail study used bovine peptides at 2.5 g.^{1, 4}

Can collagen help hair shedding after having a baby?

No trial has tested it. Shedding after childbirth follows the telogen pattern, and the NHS's rule for temporary hair loss is that it grows back, with a GP if you are worried.^{6, 7} Collagen in pregnancy and breastfeeding has the rest.

Sources

1. Hexsel D, et al. Journal of Cosmetic Dermatology, 2017. PubMed 28786550.
2. Vleminckx S, et al. Influence of collagen peptide supplementation on visible signs of skin and nail health and -aging in an East Asian population: a double blind, randomized, placebo-controlled trial. Journal of Cosmetic Dermatology, 2024. PubMed 39143887.
3. Matsumura H, et al. Hair follicle aging is driven by transepidermal elimination of stem cells via COL17A1 proteolysis. Science, 2016. PubMed 26912707.
4. Hwang S, et al. Low-molecular-weight collagen peptide supplementation improves cellulite severity, skin elasticity, and hair shaft diameter: a clinical study with pharmacokinetic evaluation. Journal of Medicinal Food, 2026. PubMed 41788055.
5. Milani M, Colombo F. Skin Research and Technology, 2023. PubMed 37357646.
6. NHS. Hair loss. nhs.uk
7. Malkud S. Telogen effluvium: a review. Journal of Clinical and Diagnostic Research, 2015. PubMed 26500992.
8. NHS. Iron deficiency anaemia. nhs.uk
9. NHS. Underactive thyroid: symptoms. nhs.uk
10. NHS. Overactive thyroid: symptoms. nhs.uk
11. Regulation (EU) No 432/2012 (assimilated GB law), Annex: permitted health claims. legislation.gov.uk
12. NHS. B vitamins and folic acid (biotin). nhs.uk
13. NHS. Others: vitamins and minerals (zinc, copper). nhs.uk