Vitamins are essential organic compounds that our bodies need for various important biological functions such as growth, immune function, and metabolism. Vitamins cannot be produced by our bodies (or only in small amounts), and therefore we depend on food for their intake. There are thirteen essential vitamins, including vitamin A, B-complex (B1, B2, B3, B5, B6, B7, B9, B12), C, D, E, and K, each with its own unique functions in the body.