You can use gelatin for strengthening hair, also. Just add a teaspoon (or less if your hair is short) directly to the shampoo and mix it in your palm before shampooing.
Or do a hair mask: 1 tablespoon of Gelatin powder in 1/2 cup of cool water until mixed. Add 1/2 cup warm/hot water, 1 teaspoon of apple cider vinegar and 1 teaspoon of honey to create a thick gel/liquid. Pour into hair and massage through hair and scalp. Leave on for at least 5 minutes and rinse with hot water. Shampoo as normal.