Keratin is the protein that gives hair its strength. Hair is composed of 80-85% keratin, which is a type of protein made up of amino acids. Keratin is also found in nails and skin, and it provides support and structure to these tissues. Amino acids are the building blocks of proteins, and they can be divided into two categories: essential and non-essential. Essential amino acids cannot be synthesized by the body and must be obtained through the diet. Therefore, consuming a protein-rich diet is essential for healthy hair growth. Some good sources of protein include fish, eggs, red meat, poultry, cheese, beans, quinoa, tofu, seitan, legumes, and nuts. In addition to proteins such as keratin and collagen, you may consider looking for hair products that contain either natural or synthetic oils, such as argan oil or silicone, respectively, to help restore strength and hydration to your hair.