Vitamins are organic substances that are essential for normal cell function, growth, and development. They are generally classified as either fat-soluble or water-soluble. Fat-soluble vitamins, such as A, D, E, and K, dissolve in fat and tend to accumulate in the body, while water-soluble vitamins, such as C and the B-complex vitamins, must dissolve in water before they can be absorbed by the body and cannot be stored. Vitamins are obtained from the food we eat, and their precise requirements have been the subject of research and controversy since their discovery in the late 1800s and early 1900s
. There are 13 essential vitamins, including A, C, D, E, K, and the B vitamins, each of which has an important role in the body
. Most people should get all the vitamins they need by having a varied and balanced diet, although some people may need to take extra supplements
