Vitamins are organic compounds necessary in small amounts in the diet for the normal growth and maintenance of life of animals, including man. They do not provide energy,【C1】______ do they construct or build any part of the body. They are needed for transforming foods into energy and body maintenance. There are thirteen or more of them, and if【C2】______ is missing a deficiency disease becomes【C3】______ . Vitamins are similar because they are made of the same elements—usually carbon, hydrogen, oxygen, and sometimes nitrogen. They are different【C4】______ their elements are arranged differently, and each vitamin【C5】______ one or more specific functions in the body.【C6】______ enough vitamins is essential to life,【C7】______ the body has no nutritional use for【C8】______ vitamins. Many people,【C9】______ , believe in being on the "safe side" and thus take extra vitamins. However, a【C10】______ diet will usually meet all the body's vitamin needs.