Đang chuẩn bị liên kết để tải về tài liệu:
Chapter 070. Nutritional Requirements and Dietary Assessment (Part 4)

Estimated Average Requirement When florid manifestations of the classic dietary deficiency diseases such as rickets, scurvy, xerophthalmia, and protein-calorie malnutrition were common, nutrient adequacy was inferred from the absence of their clinical signs. Later, it was determined that biochemical and other changes were evident long before the clinical deficiency became apparent. Consequently, criteria of nutrient adequacy are now based on biologic markers when they are available. Priority is given to sensitive biochemical, physiologic, or behavioral tests that reflect early changes in regulatory processes or maintenance of body stores of nutrients. Current definitions focus on the amount of a nutrient. | Chapter 070. Nutritional Requirements and Dietary Assessment Part 4 Estimated Average Requirement When florid manifestations of the classic dietary deficiency diseases such as rickets scurvy xerophthalmia and protein-calorie malnutrition were common nutrient adequacy was inferred from the absence of their clinical signs. Later it was determined that biochemical and other changes were evident long before the clinical deficiency became apparent. Consequently criteria of nutrient adequacy are now based on biologic markers when they are available. Priority is given to sensitive biochemical physiologic or behavioral tests that reflect early changes in regulatory processes or maintenance of body stores of nutrients. Current definitions focus on the amount of a nutrient that minimizes the risk of chronic degenerative diseases. The EAR is the amount of a nutrient estimated to be adequate for half of the healthy individuals of a specific age and sex. The types of evidence and criteria used to establish nutrient requirements vary by nutrient age and physiologic group. The EAR is not useful clinically for estimating nutrient adequacy in individuals because it is a median requirement for a group 50 of individuals in a group fall below the requirement and 50 fall above it. Thus a person with a usual intake at the EAR has a 50 risk of an inadequate intake. For these reasons other standards described below are more useful for clinical purposes. Recommended Dietary Allowances The RDA is the nutrient-intake goal for planning diets of individuals it is used in the MyPyramid food guide of the U.S. Department of Agriculture USDA therapeutic diets and descriptions of the nutritional content of processed foods and dietary supplements. The nutrient content in a food is stated by weight or as a percentage of the daily value DV a variant of the RDA that for an adult represents the highest RDA for an adult consuming 2000 kcal d. The RDA is the average daily dietary intake level that meets .