L-Cysteine yog ib qho ntawm 20 natural amino acids thiab, dhau li ntawm methionine, tsuas yog ib qho uas muaj leej faj.Nws yog thiol-muaj cov amino acid uas tsis tseem ceeb uas yog oxidized los ua Cystine.Nws yog ib qho tseem ceeb tsis muaj leej faj-muaj cov amino acid nyob rau hauv tib neeg, muaj feem xyuam rau cystine, Cysteine tseem ceeb rau protein synthesis, detoxification, thiab ntau yam metabolic zog.Pom muaj nyob rau hauv beta-keratin, cov protein tseem ceeb hauv cov rau tes, tawv nqaij, thiab plaub hau, Cysteine tseem ceeb hauv kev tsim collagen, nrog rau cov tawv nqaij elasticity thiab kev ntxhib los mos.