To determine healthful nutrition standards, the Food and Nutrition Board of the National Academy of Sciences (NAS), a nonprofit, scholarly society that advises the United States government, periodically assembles committees of national experts to update and assess nutrition guidelines.
The NAS first published its Recommended Dietary Allowances (RDAs) in 1941.
An RDA reflects the amount of a nutrient in the diet that should decrease the risk of chronic disease for most healthy individuals.
The NAS originally developed the RDAs to ensure that World War II soldiers stationed around the world received enough of the right kinds of foods to maintain their health.
The NAS periodically has updated the RDAs to reflect new knowledge of nutrient needs.
In the late 1990s the NAS decided that the RDAs, originally developed to prevent nutrient deficiencies, needed to serve instead as a guide for optimizing health.
Consequently, the NAS created Dietary Reference Intakes (DRIs), which incorporate the RDAs and a variety of new dietary guidelines.
As part of this change, the NAS replaced some RDAs with another measure, called Adequate Intake (AI).
Although the AI recommendations are often the same as those in the original RDA, use of this term reflects that there is not enough scientific evidence to set a standard for the nutrient.
Calcium, which has an AI of 1,000 to 1,300 mg per day, is not an RDA because scientists do not yet know how much calcium is needed to prevent osteoporosis.
Tolerable Upper Intake Level (UL) designates the highest recommended intake of a nutrient for good health.
If intake exceeds this amount, health problems may develop.
Calcium, for instance, has a UL of 2500 mg per day.
Scientists know that more than this amount of calcium taken every day can interfere with the absorption of iron, zinc, and magnesium and may result in kidney stones or kidney failure.
Estimated Average Requirement (EAR) reflects the amount of a particular nutrient that meets the optimal needs of half the individuals in a specified group. For example, the NAS cites an EAR of 45 to 90 grams of protein for men aged 18 to 25. This figure means that half the men in that population need a daily intake of protein that falls within that range.
To simplify the complex standards established by the NAS, the United States Department of Agriculture (USDA) created the Food Guide Pyramid, a visual display of the relative importance to health of six food groups common to the diet.
The NAS first published its Recommended Dietary Allowances (RDAs) in 1941.
An RDA reflects the amount of a nutrient in the diet that should decrease the risk of chronic disease for most healthy individuals.
The NAS originally developed the RDAs to ensure that World War II soldiers stationed around the world received enough of the right kinds of foods to maintain their health.
The NAS periodically has updated the RDAs to reflect new knowledge of nutrient needs.
In the late 1990s the NAS decided that the RDAs, originally developed to prevent nutrient deficiencies, needed to serve instead as a guide for optimizing health.
Consequently, the NAS created Dietary Reference Intakes (DRIs), which incorporate the RDAs and a variety of new dietary guidelines.
As part of this change, the NAS replaced some RDAs with another measure, called Adequate Intake (AI).
Although the AI recommendations are often the same as those in the original RDA, use of this term reflects that there is not enough scientific evidence to set a standard for the nutrient.
Calcium, which has an AI of 1,000 to 1,300 mg per day, is not an RDA because scientists do not yet know how much calcium is needed to prevent osteoporosis.
Tolerable Upper Intake Level (UL) designates the highest recommended intake of a nutrient for good health.
If intake exceeds this amount, health problems may develop.
Calcium, for instance, has a UL of 2500 mg per day.
Scientists know that more than this amount of calcium taken every day can interfere with the absorption of iron, zinc, and magnesium and may result in kidney stones or kidney failure.
Estimated Average Requirement (EAR) reflects the amount of a particular nutrient that meets the optimal needs of half the individuals in a specified group. For example, the NAS cites an EAR of 45 to 90 grams of protein for men aged 18 to 25. This figure means that half the men in that population need a daily intake of protein that falls within that range.
To simplify the complex standards established by the NAS, the United States Department of Agriculture (USDA) created the Food Guide Pyramid, a visual display of the relative importance to health of six food groups common to the diet.
The pyramid recommends a range of the number of servings to choose from each group, based on the nutritional needs of males and females and different age groups.
In 2005 the pyramid was updated to accommodate different levels of physical exercise and caloric intake resulting in 12 unique pyramids tailored to fit individual needs.
In an effort to provide additional nutritional guidance and reduce the incidence of diet-related cancers, the National Cancer Institute developed the 5-a-Day Campaign for Better Health, a program that promotes the practice of eating five to nine servings of fruits and vegetables daily.
Studies of populations that eat many fruits and vegetables reveal a decreased incidence of diet-related cancers.
Laboratory studies have shown that many fruits and vegetables contain phytochemicals, substances that appear to limit the growth of cancer cells.
Many people obtain most of their nutrition information from a food label called the Nutrition Facts panel. This label is mandatory for most foods that contain more than one ingredient, and these foods are mostly processed foods.
Labeling remains voluntary for raw meats, fresh fruits and vegetables, foods produced by small businesses, and those sold in restaurants, food stands, and local bakeries.
The Nutrition Facts panel highlights a product’s content of fat, saturated fat, cholesterol, sodium, dietary fiber, vitamins A and C, and the minerals calcium and iron.
The stated content of these nutrients must be based on a standard serving size, as defined by the Food and Drug Administration (FDA).
Food manufacturers may provide information about other nutrients if they choose.
However, if a nutritional claim is made on a product’s package, the appropriate nutrient content must be listed. For example, if the package says “high in folic acid,” then the folic acid content in the product must be given in the Nutrition Facts panel.
The Nutrition Facts panel also includes important information in a column headed % Daily Value (DV).
DVs tell how the food item meets the recommended daily intakes of fat, saturated fat, cholesterol, carbohydrates, dietary fiber, and protein necessary for nutritional health based on the total intake recommended for a person consuming 2,000 calories per day.
One portion from a can of soup, for example, may have less than 2 percent of the recommended daily value for cholesterol intake.
Health-conscious consumers can use the Nutrition Facts panel to guide their food choices. For example, based on a daily diet of 2,000 calories, nutrition experts recommend that no more than 30 percent of those calories should be from fat, which would allow for a daily intake of around 65 grams of fat.
A Nutrition Facts panel may indicate that a serving of one brand of macaroni and cheese contains 14 grams of fat, or a % DV of 25 percent.
This tells the consumer that a serving of macaroni and cheese provides about one-fourth of the suggested healthy level of daily fat intake.
If another brand of macaroni and cheese displays a % DRV of 10 percent fat, the nutrition-conscious consumer would opt for this brand.
Nutritionists and other health experts help consumers make good food choices.
People who study nutrition in college may refer to themselves as nutritionists; often, however, the term refers to a scientist who has pursued graduate education in this field.
A nutritionist may also be a dietitian. Dietitians are trained in nutrition, food chemistry, and diet planning.
In the United States, dietitians typically have graduated from a college program accredited by the American Dietetic Association (ADA), completed an approved program of clinical experience, and passed the ADA’s registration examination to earn the title Registered Dietitian (RD).
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