Even with the best nutritional planning, it is difficult to maintain a diet that meets the RDAs for all nutrients. For example, vegetarians, who as a group are healthier than meat eaters (and who tend to avoid junk foods lacking in vitamins and minerals), still may be deficient in some nutrients, such as iron, calcium, and vitamin B12. And most people who want to maintain a healthy low-fat diet will have a problem obtaining the recommended amounts of vitamin E from their food alone, because so many of the food sources for vitamin E are high in fat. Another complication is that a balanced diet may not contain the more specialized substances -- fish oils, soy isoflavones, or alpha-lipoic acid -- that researchers think may promote health. For generally healthy people who cannot always eat a well-balanced diet every day, a supplement can fill in these nutritional gaps or boost the nutrients they consume from adequate to optimal. Check out the chart on the following pages to learn the types of vitamins and minerals you should take, depending upon your eating habits.

The Vitamins You Need

This chart shows the vitamins and minerals that should be in a basic daily supplement formula, and the amounts of each that can help you obtain preventive benefits. (The RDA, short for recommended dietary allowance, is the amount of a nutrient needed to prevent a deficiency in 97 to 98 percent of a population, as determined by the Food and Nutrition Board of the National Research Council.)