Along with tofu, soybeans, starchy beans, and black-eyed peas, lentils are a great vegetarian source of iron-rich protein, which I recommend for two reasons. First, protein is necessary for all cell growth, including hair cells. Hair gets its structure from hardened proteins called keratin. Without enough protein for keratin, hair grows more slowly, and the individual strands that do grow are weaker. Second, the iron found in animal foods (called heme iron) — such as lean beef, turkey, chicken, or pork — is more easily absorbed by the body than the iron in plant foods (non-heme iron). So, if you are a vegetarian, it's especially important to fill your plate with the most iron-rich plant foods. Additionally, you should combine your iron-rich vegetables with foods high in vitamin C, because vitamin C improves the body's ability to absorb non-heme iron.