Taking nutritional supplements can provide additional nutrients when your diet inadequate or when certain health conditions cause you to develop an insufficiency or deficiency.
In most cases, multiple-vitamin supplements provide all the basic micro nutrients (vitamins and minerals) your body needs. These multiple vitamins are generally safe because they contain only small amounts of each nutrient. Individual nutrients are available for purchase, but usually are in larger amounts than what's found in a typical multiple-vitamin.
Before making decisions about whether to take a supplement, talk to your healthcare provider. They can help you achieve a balance between the foods and nutrients you personally need.