It is estimated that nearly 40 percent of Americans take a multivitamin every day. Multivitamins have been recommended for several years, but there have been questions raised about whether or not they are really necessary. Ideally, if you eat a well-balanced diet that is rich in whole grains, vegetables and fruits, you will get all of the nutrients that you need. However, the typical American diet is usually lacking in one or more of the essential nutrients. That is why a multivitamin is necessary for many people.