“Cystine?”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.
An amino acid formed from two molecules of cysteine joined together. It occurs naturally in dietary protein and in the body's own protein structures, including hair and skin keratin.
Why it’s used
Taken by some as a building block related to cysteine, sometimes marketed for hair, skin, or nail support, or as part of general amino acid formulas.
What the evidence says
There is little dedicated human clinical research on cystine supplementation itself, as distinct from its more commonly studied precursor form, N-acetylcysteine. Claims about hair or skin benefits from cystine supplementation specifically have not been well established in controlled trials.
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: 1900 records · searched September 2026
"Cystine"[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: 31 records · searched September 2026
"Cystine"[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: 12522 records · searched September 2026
"Cystine"[Title/Abstract]
This says what this database holds under these terms. It is not a finding that no research exists.
Context
No standard studied dosing protocol for cystine as a standalone supplement has been established in the available literature.
Rumors
Cystine can cause kidney stones.
Sources cited — check not cleared.
Studied in: people with cystinuria (a genetic disorder of renal cystine reabsorption).
Measured as an outcome.
- Cystinuria: an inborn cause of urolithiasis (Peer-reviewed) · Funding not checked · No conflicts declared
- The Impact of Diet on Urinary Risk Factors for Cystine Stone Formation (Peer-reviewed) · Funding not clearly stated · No conflicts declared
Who’s saying this
- Synapse — a brand: pharmaceutical intelligence database; Patsnap product
How we know who this is
- “Synapse provides users with a 360-degree view of the competitive and technology landscape!” (their page)
- “This report uses Patsnap Analytics, Bio, and Synapse to examine how oligonucleotide IP is evolving across four strategic questions: • Who owns the core patent estate across approved products, clinical candidates, and enabling platforms?” (their page)
Cystine acts as an antioxidant in the body, protecting tissues and skin.
Not gradedhealth and safety evidence
Sources cited — no verdict reached.
What was measured is not yet noted.
- Oral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patients (Peer-reviewed) · Funded by Ajinomoto Co., Inc. (industry) · No conflicts declared
- Effects of oral cystine and glutamine on exercise-induced changes in gastrointestinal permeability and damage markers in young men (Peer-reviewed) · Funded by Ajinomoto Co., Inc. (industry) · Authors declare a conflict of interest
Who’s saying this
- community.bulksupplements.com — the site doesn’t say who runs it
L-cystine in supplements brightens the skin and improves complexion.
Supports — suggestivehealth and safety evidence
Measured as an outcome.
- Metabolic Basis and Clinical Evidence for Skin Lightening Effects of Thiol Compounds (Peer-reviewed) · Funding not checked
Who’s saying this
- Amazon.com, Inc. — a retailer: online store selling products across many departments
How we know who this is
- “© 1996-2026, Amazon.com, Inc. or its affiliates” (their page)
Cystine supplements promote hair growth and slow 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
- bailleul.com — we haven’t checked who runs this site yet
Taking cystine supplements causes nausea and stomach upset.
Does not support — suggestivehealth and safety evidence
Studied in: gastrointestinal cancer patients receiving S-1 adjuvant chemotherapy after surgery.
Measured as an outcome.
- Oral administration of the amino acids cystine and theanine attenuates the adverse events of S-1 adjuvant chemotherapy in gastrointestinal cancer patients (Peer-reviewed) · Funded by Ajinomoto Co., Inc. (industry) · No conflicts declared
Who’s saying this
- community.bulksupplements.com — the site doesn’t say who runs it