3. Vitamin C
Free radical damage can block growth and cause your hair to age. Vitamin C is a powerful antioxidant that helps protect against the oxidative stress caused by free radicals. In addition, your body needs vitamin C to create a protein known as collagen — an important part of hair structure.
Vitamin C also helps your body absorb iron, a mineral necessary for hair growth. Strawberries, peppers, guavas and citrus fruits are all good sources of vitamin C.