amino acid · for brittle nails
Collagen
Supplies the building blocks nails are made from, and speeds how fast they grow.
Say that in clinical terms
Collagen peptides provide structural amino acids for nail matrix keratin synthesis. Increases nail growth rate.
How strong is the research?
Evidence evidence
Only one studyStudied in a narrower groupIndustry fundedLow-quality evidence
2 papers read, 1 supporting.
Tested as: specific bioactive collagen peptides, 2.5 g/day
Who was studied: 25 women at a single Brazilian skin clinic.
How much to take
daily
2.5–5 g
Limited but promising evidence. Effects observed after 24 weeks of consistent supplementation.
Before you take it
- No NIH/IOM Tolerable Upper Intake Level established for collagen peptides at any dose
- No clinically significant drug interactions documented at standard supplement doses (2.5–15 g/day); persons taking anticoagulants, antihypertensives, or immunosuppressants should consult a physician before use
- Insufficient clinical safety data for use during pregnancy and lactation — avoidance is recommended in the absence of safety studies, not because harm is documented
- Minor GI side effects (bloating, early satiety) reported in the first 1–2 weeks of use, particularly at higher doses; typically transient and self-limiting
- Hypersensitivity risk in persons with known allergies to source animal proteins (bovine, porcine, or marine depending on collagen source); source should be confirmed on product labeling
What we make of it
Open-label with no placebo group, despite our label.
The detail
The study was single-arm and open-label — everyone knew they were taking it and there was no comparison group — despite being recorded as a randomised trial. The 12% growth figure has to be read in that light.