The Recommended Dietary Allowances (RDA) provide the essential-nutrient intake levels required to meet the known nutritional needs of most (97-98%) healthy persons in specific age and gender groups. The RDA is set two standard deviations above the estimated mean requirement, and has been developed by the Food and Nutrition Board of the National Academy of Sciences. The last RDA released was in 1989.
The RDA are currently under revision; values for certain nutrients have been released periodically over the past few years. The new recommendations are called Dietary Reference Intakes (DRI), and include four levels of values: 1) Recommended Dietary Allowances (RDA); 2) Adequate Intakes (AI); 3) Tolerable Upper Intake Level (UL); and 4) Estimated Average Requirement (EAR).
Recommended Dietary Allowances have the same meaning in the new revision as in the previous version. The RDA are meant to be used as a goal for dietary intake for individuals. The RDA are not necessarily intended to be used for assessing the diets of individuals or groups, or planning for groups, although that is how they are most often used. Table 2 provides 1998 RDA for those nutrients that have revised values.
Adequate intake values are set for nutrients for which no EAR has been set. These values are based on observation or experimentation, and measure the average intake of a population that appears to sustain a nutritional state such as normal circulating nutrient values or growth. Table 3 below contains the AI for those nutrients for which a value has been allotted.
The Estimated Average Requirement is the nutrient-intake value that is estimated to meet the requirement in 50% of the individuals in an age and gender group. The EAR is used in setting the RDA. The EAR for selected nutrients is shown in Table 4, below.
The Tolerable Upper Intake Level is the maximal level of nutrient intake that will not pose risks of adverse health effects in most individuals. The UL do not imply, however, that a beneficial effect will occur if that level of nutrient is consumed.
The Dietary Guidelines for Americans have been published every five years since 1980 by the U.S. Department of Agriculture and Health and Human Services. Their purpose is to provide the basis for federal nutrition policy and nutrition education activities, and they offer advice as to food choices that promote health and prevent disease in Americans ages two and older.
The 2000 Dietary Guidelines for Americans are:
1) Aim for Fitness: Aim for a healthy weight Be physically active each day Let the food pyramid guide your food choices (see below) 2) Build a Healthy Base: Choose a variety of grains daily, especially whole grains Choose a variety of fruits and vegetables daily Keep food safe to eat 3) Choose Sensibly: Choose a diet that is low in saturated fat and cholesterol and moderate in total fat Choose beverages and foods to moderate your intake of sugars Choose and prepare foods with less salt If you drink alcoholic beverages, do so in moderation
The Food Guide Pyramid was created by the U.S. Department of Agriculture to help Americans choose foods from each food grouping. The focus of the pyramid is on fat, which most Americans over-consume. The base of the pyramid comprises foods that should be consumed in the greatest quantity; the top of the pyramid comprises foods that should be consumed sparingly.
Starting from base to top, the food groups and number of servings that should be consumed daily are as follows:
Breads, Cereal, Rice, Pasta: 6-11 servings Vegetables: 3-5 servings Fruit: 2-4 servings Meat, Poultry, Fish, Beans, Eggs, Nuts: 2-3 servings Milk, Yogurt, Cheese: 2-3 servings Fats, Oils, Sweets: Use sparingly
Healthy People 2000: National Health Promotion and Disease Prevention Objectives is a national preventive strategy for improving the health of Americans. The Secretary of Health and Human Services submits the guidelines to Congress. Reports are compiled by the National Center for Health Statistics, and the Centers for Disease Control. The guidelines have three major goals and 319 objectives. The three goals are: to increase the span of a healthy life; to decrease health disparities; and to achieve access to preventive services for everyone. One or more agencies of the U.S. Public Health Service are designated to coordinate the activities.