research Efficacy and Safety of L-Cystine Associated or not to a Natural Keratin (Kera-Dietandreg;) Hydrolysate on Hair and Nails: Randomised, Placebo-Controlled, Clinical Trial on Healthy Females
In this study, researchers found that supplementation with L-cystine, either alone or with a keratin hydrolysate, significantly improved hair density, hair and nail brightness, and nail growth in women experiencing acute telogen effluvium and brittle nail syndrome over three months.
