“Keratin?”Here!
Hasn’t appeared in a scanned product yet.
As a supplement
Talk to your doctor or pharmacist.
Roll Call does not check drug interactions or assess personal safety.
A structural protein rich in sulfur-containing amino acids — the same protein that makes up hair, nails, and the outer layer of skin. Supplement forms are usually hydrolyzed from animal sources such as wool or feathers.
Why it’s used
Taken by some for hair and nail strength or appearance.
What the evidence says
Oral keratin supplementation has been examined only in small, mostly industry-associated trials; there is no robust, independently replicated body of evidence establishing an effect on hair or nail growth from taking it by mouth.
Where we looked
There was no paper to cite here, so this is the search instead — run it yourself and see what we saw.
- PubMed: 2741 records · searched September 2026
"Keratin"[Title/Abstract] AND (review[pt] OR "safety assessment"[Title/Abstract] OR "risk assessment"[Title/Abstract] OR toxicology[Title/Abstract] OR toxicity[Title/Abstract] OR characterization[Title/Abstract] OR characterisation[Title/Abstract]) - PubMed: 9 records · searched September 2026
"Keratin"[Title/Abstract] AND ("dietary supplements"[MeSH] OR supplementation[Title/Abstract] OR supplement[Title/Abstract] OR supplements[Title/Abstract] OR "oral administration"[Title/Abstract]) AND (randomized controlled trial[pt] OR clinical trial[pt] OR meta-analysis[pt] OR systematic review[pt]) AND humans[MeSH] - PubMed: 19983 records · searched September 2026
"Keratin"[Title/Abstract]
This says what this database holds under these terms. It is not a finding that no research exists.
Context
Small trials on nail brittleness used daily oral hydrolyzed keratin over several months, but sample sizes were small and results have not been widely replicated.
Rumors
Keratin supplements strengthen hair and promote hair growth.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- Life Extension — a brand: sells its own vitamins and supplements
How we know who this is
- “Life Extension is a privately owned vitamin and supplement company.” (their page)
- Life Extension — a brand: sells its own vitamins and supplements
Keratin supplements prevent and even reverse hair loss.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- NAOMI — a brand: sells science-backed wellness supplements
How we know who this is
- “At NAOMI, every formula starts with research—not trends.” (their page)
- “That’s why over 100,000 customers trust NAOMI for real results in their health and wellness journey.” (their page)
- NAOMI — a brand: sells science-backed wellness supplements
Taking too much keratin causes thick, rough, dry skin.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- NAOMI — a brand: sells science-backed wellness supplements
How we know who this is
- “At NAOMI, every formula starts with research—not trends.” (their page)
- “That’s why over 100,000 customers trust NAOMI for real results in their health and wellness journey.” (their page)
- NAOMI — a brand: sells science-backed wellness supplements
Keratin supplements strengthen nails and prevent brittle, cracked nails.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- Crushed Tonic — a brand: sells collagen drink supplements
How we know who this is
- “That unexpected discovery sparked years of research— and eventually, Crushed Tonic.” (their page)
- “✓ 5,000mg of hydrolyzed marine collagen in every drink” (their page)
- Crushed Tonic — a brand: sells collagen drink supplements
Keratin supplements reduce wrinkles and improve skin moisture and elasticity.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- Life Extension — a brand: sells its own vitamins and supplements
How we know who this is
- “Life Extension is a privately owned vitamin and supplement company.” (their page)
- Life Extension — a brand: sells its own vitamins and supplements