Who hasn’t heard of keratin and keratin treatments, right? But did you know that keratin is one of the most abundant proteins in the skin & the hair and contains high amounts of L-cysteine as a building block. L-cysteine provides strength & rigidity to keratin. And L-cysteine is one of the 22 micronutrients available in Perfectil. [Source: Molecules. 2018 Mar; 23(3): 575 Perfectil notes]