Methionine is an essential sulfur-containing amino acid that functions as an antioxidant through its easily oxidized sulfur atom — acting as a sacrificial target for reactive oxygen species. It is the initiating amino acid for all protein synthesis and serves as a methyl group donor (SAMe pathway) critical for DNA repair and cellular function. In skincare, methionine protects cellular proteins from oxidative damage and supports healthy cell function.
Key Skin Benefits
+ Sacrificial antioxidant — sulfur atom neutralizes ROS
+ Initiating amino acid for protein synthesis
+ SAMe precursor — methylation for DNA repair
+ Protects cellular proteins from oxidative damage
+ Hair conditioning amino acid
Pros
+ + Direct antioxidant via sulfur
+ + Supports protein/DNA synthesis
+ + Cellular protection
+ + Essential amino acid
+ + Hair benefits
Cons
− − Can be unstable in formulations
− − Limited cosmetic research as monotherapy
− − Not a primary skincare active
Specifications
Property
Value
Usage Areas
Face, Eye, Body, Hair
Product Type
Leave-On, Rinse-Off
Source
Synthetic / Fermentation
Natural Level
Natural-derived
Safety Ratings
Metric
Rating
Skin Sensitivity
1/5
Comedogenic Rating
0/5
EWG Score
1/10
Regional Regulatory Limits
Region
Leave-on %
Rinse-off %
Status
EU (CosIng)
No limit
No limit
Allowed
US (CIR/FDA)
No limit
No limit
Allowed
Japan (MHLW)
No limit
No limit
Allowed
ASEAN
No limit
No limit
Allowed
China (NMPA)
No limit
No limit
Allowed
Typical Usage % by Product Type
Product Type
Typical %
Serum
0.05 - 0.5%
Hair Treatment
0.5 - 1%
References
Levine RL et al. — Methionine oxidation. IUBMB Life (2000). PMID: 11128672
Stadtman ER et al. — Methionine antioxidant role. Biochim Biophys Acta (2005). PMID: 15652134
Loenen WA — SAMe and methylation. Biochem Soc Trans (2006). PMID: 16545191