In this guide
What is Keratin Supplements?
Keratin supplements are processed protein hydrolysates, often from feathers. Finished-product trials do not show that intact keratin travels to hair, nails or skin. No U.S. RDA, AI, UL or established hair, nail or skin treatment dose exists for keratin. Study products differ in hydrolysis and co-ingredients. [1]
Typical Keratin Supplements Protocols
| Source and population | Form and amount each time | Frequency | Total exposure | Duration or boundary |
|---|---|---|---|---|
| Beer 2014 · 50 women | Two capsules containing keratin 500 mg total plus vitamins/minerals | Once daily as two capsules | 500 mg/day keratin in a combination | 90 days; hair and nail endpoints |
| Tursi 2025 · healthy women with aging signs | Feather keratin hydrolysate 500 mg or 1,000 mg/day | Daily; administration count not stated in abstract | 500 or 1,000 mg/day | 90 days; skin, hair and nail measures |
| Crum 2018 · 15 endurance-trained men | Soluble keratin 0.8 g/kg/day | Daily; schedule details in full report | Weight-based daily total | 4 weeks crossover versus casein |
These rows reproduce sources. Do not average them into one universal regimen.
From source to outcome
Usually feather-derived protein.
Co-ingredients and sponsors matter.
No cycling benefit in 15 men.
Which forms and label details matter?
Record feather or other source, hydrolysis method, keratin or amino-acid mass, protein content, vitamins/minerals, allergen declarations and proprietary name.
How should it be stored?
Follow the label, close the container and protect it from heat, light and moisture.
Read the label before the claim
Keep the tested preparation.
Do not infer a universal regimen.
Appearance is not disease treatment.
What is it commonly used for?
Products target hair shedding, shine, nail strength and skin appearance; high-dose soluble keratin is also marketed as protein. Evidence comes from small sponsor-linked or multi-ingredient studies.
What does human research show?
Beer randomized 50 women to a two-capsule finished product containing 500 mg keratin plus vitamins and minerals or placebo for 90 days. Hair and nail measures favored the combination, but the design cannot isolate keratin and included product-linked authorship. [2] Tursi randomized women to 500 or 1,000 mg/day of a feather keratin hydrolysate or placebo for 90 days and reported improvements across selected skin, hair and nail measures; company investigators and a proprietary preparation limit transfer. [3] Crum compared 0.8 g/kg/day soluble keratin with casein in 15 trained men over four-week crossover periods. Keratin did not improve cycling performance or oxygen-consumption outcomes; a lean-mass signal in this tiny study does not establish superiority as protein. [4]
How might it act?
Keratin hydrolysates provide amino acids and small peptides after digestion. Structural keratin in hair and nails is produced by living cells; consuming keratin does not mean intact protein is deposited there.
How does it compare with related products?
| Product | Identity to preserve | Evidence boundary |
|---|---|---|
| Collagen | Source, hydrolysis and peptide grams | Skin findings are sensitive to funding and study quality |
| Hyaluronic acid | Hyaluronan mass and molecular weight | Small product-linked oral trials |
| Keratin | Hydrolysate source and co-ingredients | Finished-product evidence cannot isolate generic keratin |
| Astaxanthin | Natural or synthetic source and active mg | Small skin trials do not establish disease prevention |
What are the risks and interactions?
Source allergy, GI symptoms and co-ingredient excess are the main practical concerns. Feather-derived products may conflict with dietary preferences. Review kidney disease requiring protein management, pregnancy, breastfeeding and duplicate vitamins or minerals.
Which medicines require review?
Have the product reviewed with medicines, before surgery, and during pregnancy or breastfeeding. No universal separation interval is established.
Regulatory status: In the United States, supplements generally lack premarket efficacy approval. In Canada, verify the finished product’s NPN or DIN-HM and licensed conditions. [1], [5]
What should be monitored?
Record product, lot, form, amount per administration, frequency, daily total, co-ingredients, meals, symptoms, medicines, chosen outcome and review date.
What happens when it is stopped?
No ingredient-specific withdrawal syndrome is established. Record the stop date, symptoms and chosen outcome; seek care for a persistent serious symptom.
Seek prompt care for a serious allergic reaction, unusual bleeding, persistent palpitations, chest pain or another severe symptom.
What do public communities report?
Public reports can suggest questions to track, but they do not verify the product, dose or causality. This update did not newly quantify a community sample.
Common questions about Keratin Supplements
Does oral keratin become hair?
No. It is digested; intact deposition into hair is not established.
Did the 500 mg trial isolate keratin?
No. The finished product also contained vitamins and minerals.
Are feather hydrolysates vegan?
No. They are poultry-derived unless another source is explicitly stated.
Does keratin improve exercise performance?
The 15-man crossover trial found no cycling-performance benefit.
Is 1,000 mg an established dose?
No. It is a source-specific study exposure.
What should I track?
Source, hydrolysis, active amount, total protein, co-ingredients, hair/nail measure and review date.
Glossary
Terms for reading the evidence.
- Active amount
- The declared amount of the studied ingredient, distinct from total blend mass.
- Formulation
- Source, processing, molecular size and co-ingredients that define the tested product.
- Randomized controlled trial
- A study assigning participants to intervention or comparator by chance.
- Funding sensitivity
- A result pattern that changes when studies are grouped by sponsor support.
- Endpoint
- The prespecified measurement used to judge a study result.
- Generalizability
- How well a result applies beyond the exact study product and population.
How this guide was researched
Accessible official sources and human reports were read on October 9, 2026. Titles, authors, journals, DOI, PMID and visible corrections were checked. An unreported frequency was not guessed.
How this guide was made
Research and drafting were AI-assisted. This draft awaits Doserly editorial review and independent clinical review. See the editorial policy.
Explore the sources
Sources preserve form, amount, frequency, population, duration and outcome.
Showing 5 sources
- 01
Questions and Answers on Dietary Supplements ↗
Official regulatory overview
Current page or report reviewed; scope and limits retained.
Detail: Finished-product and claim boundaries.
- 02
A clinical trial to investigate the effect of Cynatine HNS on hair and nail parameters. ↗
Randomized multi-ingredient trial
Current page or report reviewed; scope and limits retained.
Detail: 50 women; 500 mg keratin plus vitamins and minerals for 90 days.
- 03
The Effects of an Oral Supplementation of a Natural Keratin Hydrolysate on Skin Aging: A Randomized, Double-Blind, Placebo-Controlled Clinical Study in Healthy Women. ↗
Randomized cosmetic trial
Current page or report reviewed; scope and limits retained.
Detail: 500 or 1,000 mg/day feather hydrolysate for 90 days; product-linked.
- 04
The effect of chronic soluble keratin supplementation in physically active individuals on body composition, blood parameters and cycling performance. ↗
Randomized crossover trial
Current page or report reviewed; scope and limits retained.
Detail: 15 men; 0.8 g/kg/day versus casein; performance null.
- 05
Product Licensing ↗
Canadian licensing overview
Current page or report reviewed; scope and limits retained.
Detail: Finished natural health products require licensing and authorized labels.
No matching sources
Try a different term or show the full list.