Quinoa, which is considered a complete protein, includes all nine necessary amino acids, which help to stronger, thicker hair. This superfood can nourish both the hair and the scalp from the inside out. Quinoa's hydrolyzed protein level can help seal broken ends, and its vitamin E content can help reduce hair loss. People who are looking to grow or restore hair should eat a healthy diet that includes proteins like quinoa. Proteins are needed for strong hair growth while vitamins help supply nutrients to the hair follicles. Eating foods high in protein and vitamins can help prevent hair loss and promote healthier hair. Spinach is another excellent source of protein that can help strengthen hair. Spinach contains iron, which helps transport oxygen to the hair shaft, making it easier to grow. A low-iron diet can lead to hair loss, so adding more spinach to your plate will help ensure you don't lose any hair over time. Zinc plays a role in over 100 enzymes in our bodies, including those responsible for hair growth. Zinc also promotes collagen production, which helps repair damage from stress and illness. Increasing your intake of foods rich in zinc will help provide strength to your hair. Fruit and vegetables are full of antioxidants, which help protect cells from damage caused by free radicals. Free radicals can cause irreversible changes to DNA in cells, which can lead to cancer later in life.