L-Cysteine
L-cysteine is a sulfur amino acid used as a glutathione precursor. Clinical evidence for supplementation is limited.
Overview
What is L-cysteine?
L-cysteine is an antioxidant and amino acid that helps to promote optimal skin, hair and immune health.
Dosage
A typical dose of L-cysteine is 500 mg per day.
Effect graph
Effect heatmap
SupplementDEX Database
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Database Snapshot
Most l-cysteine research is concentrated in a handful of conditions.
- Androgenic alopecia accounts for 1 of 2 studies (50%).
- Photorefractive keratectomy (PRK) accounts for 1 of 2 studies (50%).
- Sparse coverage remains for Androgenic alopecia, Photorefractive keratectomy (PRK).
Dietary Sources
Top dietary sources
Food sources
Sources include Almonds, Beans, Beef, Cashews, Chicken, Duck, Eggs, Fish, Lentils, Pork, Sunflower Seeds, and Turkey.
Safety
Oral L-cysteine is likely safe when consumed in amounts normally found in the diet.
Frequently Asked Questions
References
Sources2 references
SupplementDEX uses only high-quality sources to determine supplement effectiveness.
SupplementDEX Database · Androgenic alopecia
1 reference1.SupplementDEX Database: Androgenic alopecia — Efficacy and tolerability of an oral supplement containing amino acids, iron, selenium, and marine hydrolyzed collagen in subjects with hair loss (androgenetic alopecia, AGA or FAGA or telogen effluvium). A prospective, randomized, 3-month, controlled, assessor-blinded study2023
In 83 adults with hair loss on standard drug therapy, adding a collagen/amino acid/iron/selenium supplement for 12 weeks improved global assessment scores versus drugs alone (GAS 1.67 vs 0.66; p<0.001).
2.SupplementDEX Database: Photorefractive keratectomy (PRK) — Role of cysteine in corneal wound healing after photorefractive keratectomy2009
In 100 PRK patients, 200 mg/day oral L-cysteine for 14 days starting preoperatively improved corneal wound healing versus placebo.