Are vitamin and mineral supplements nutritionally the same as fresh foods?
It varies, but in most cases the answer is no. If the supplement is of a form of that specific vitamin or mineral that is derived from fresh foods, then yes. Some supplements of that type are available, but most are not. Some are forms that may be similar to what comes from fresh foods and readily absorbed by the body, even if they are not identical. In some cases, your body can utilize them the same way. In some cases, it cannot.
Vitamin C in foods comes with many co-nutrients that help the body to absorb it, deliver it to where it needs to go, and utilize it properly. Vitamin C in most supplements is ascorbic acid, which has none of the co-nutrients. Some contain bioflavonoids or some other form of a food component to aid absorption, but none are the same as getting fresh food (even the ones that are actually from food - nothing beats _fresh_ food). The same applies in other cases, though there are specific items wherein the supplement may be almost identical to the compound found in foods. It depends on the vitamin or mineral and how it is prepared. The raw, food-grown form of supplements (which is different than food-based) are the closest to fresh foods.
It depends. Vitamin C, ascorbic acid, is identical in both supplement and natural form. Others are not. (Most synthetic vitamins are not recognized by the body and are flushed out). While you may consume 100% of your RDA of a nutrient in a vitamin pill, you are probably only absorbing 10% from most pills as the binders used to compact the pills make it hard for your system to dissolve them. In the end though, supplements serve exactly their purpose- to supplement the diet and prevent deficiencies. You might eat well, but even an excellent diet won't include 100% of everything, every day. A daily multivitamin can be seen as insurance of meeting those requirements.
Fresh foods provide many more nutrients than vitamins and minerals alone, such as fiber, antioxidants and many others.
Are the vitamins and minerals in supplements identical to fresh foods? No, but they are better than trying to get everything you need out of a can.
Vitamins and mineral are great however they are not broken down and processed in the body as easily as foods are. Some vitamins such as A,D,E,K are stored in the fat cells of the body and can become dangerous if these vitamins are abused. Vitamins A,D,E,K are fat soluble vitamins. These vitamins coming from a natural food substance can be easily flushed out of the body if they become toxic, however they are harder to flush out of the body if they are taken in a pill form! All the other vitamins are water soluble which means they are stored in water and can be easily flushed out. Minerals are great for your hair,skin and nails.