If you have a diet rich with a variety of fresh vegetables and fruits, you probably don’t need extra vitamins or minerals. You can't do much damage if you do happen to consume too many vitamins because excess vitamins are mechanically expelled from the body via the urine or excrement. Vit.A and Vit.D, however, can’t be easily expelled and CAN CAUSE DAMAGE when present in abundance. In cases of treating obesity or conditions with high demands for vitamins and minerals (pregnancy, infant babies, etc.)... supplementary vitamins and minerals can help prevent diseases (anemia, rachitic, etc.).