Experts on the National Academy of Sciences’ Food and Nutrition Board, who set up the RDA, stress that these recommendations are intended for groups rather than for individuals. They tend to be more than any individual needs, since they are amounts to meet the greatest need of any person in any group.
However, the RDA are the only reliable and clear-cut set of nutrient recommendations available to most people. They are used in ways that affect each of us. Utilizing the findings of the National Academy of Sciences, the U.S. Food and Drug Administration (FDA) developed the U. S. Recommended Daily Allowances as a standard for labeling the nutrient content of products. The USRDA is now used instead of the MDR, or Minimum Daily Requirements.
If your diet is a balanced one and you have no special medical needs, you can be confident that your vitamin intake is adequate. By eating each day four servings of bread and cereal products, four or more servings of fruits and vegetables (including one fresh fruit or fruit juice or one uncooked vegetable), two servings of dairy products, and two servings of meat, fish, or poultry, a healthy adult will obtain all needed nutrients. Even if the quality of your diet varies, your body can adapt accordingly. Although the RDA are based on daily intake, you can achieve nutritional balance over a period of a week or so. Bear in mind, however, that prolonged vitamin shortages can cause health problems, and prolonged avoidance of one or more of the Basic Four Food Groups can produce such a vitamin shortage.