Question: Is it necessary to take vitamins or supplements for nutritional purposes?
Answer: There's really no substitute for a balanced, healthy diet. You get many things out of food that you really could not get out of just taking vitamins -- things like high levels of fiber and so forth. But the important thing to remember is that it's very difficult to achieve that level of balance in your diet, so vitamins can be used to supplement until you really get a handle on eating an overall healthy diet.
They can effectively work to give you some of the vitamins that are missing from your diet. They can be a very useful tool in the overall nutritional approach, but don't overdo it. Putting large amounts of vitamin C to fend off certain illnesses and so forth is really not that effective because generally your body is very limited in how much of these vitamins it can absorb. So taking a general multivitamin that has the proper balance between the various vitamins and minerals allows your body to absorb those effectively and gives them in the quantities that your body can use healthfully.