Last Updated on December 16, 2022 by Gaga Keratin is a fibrous structural protein naturally found in our hair, skin, and nails. Human hair consists of keratin (up to 95%) and small amounts of lipids, water, and pigments. The middle layer of hair- the cortex– is made of keratin proteins that keep hair strong end … Continue reading Keratin Shampoos: Ingredients, Benefits, and Tips for Buying