Porth's Essentials of Pathophysiology, 4e

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Disorders of Nutritional Status

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Dietary Reference Intakes The Dietary Reference Intakes (DRIs) are a set of ref- erence values that identify the level of nutrient intake an individual needs to maintain health and decrease the risk for disease. 5 They are published by the National Academy of Sciences and are periodically reviewed and updated by the Institute of Medicine’s Food and Nutrition Board. A complete database of the DRIs is available online through the United States Department of Agriculture Food and Nutrition Information Center. 6 The DRIs are a set of reference values that identify the recommended estimated average requirement, dietary allowance, adequate intake, tolerable upper intake level, and acceptable macronutrient distribution range, each of which has specific uses. 5 An Estimated Average Requirement (EAR) is the intake that meets the esti- mated nutrient need of half of the persons in a specific group. This figure is used as the basis for developing the Recommended Dietary Allowance (RDA), which defines the nutrient intakes that meet the needs of almost all healthy persons in a specific age and sex group. 5 The Adequate Intake (AI) is set when there is not enough sci- entific evidence to derive an EAR and therefore the RDA. The AI is derived from experimental or observational data that show a mean intake that appears to sustain a desired indicator of health. The Tolerable Upper Intake Level (UL) is the maximum intake that is judged unlikely to pose a health risk in almost all healthy persons in a specified group. It refers to the total intake from food, fortified food, and nutrient supplements. This value is not intended to be a recommended level of intake, and there is no established benefit for persons who consume nutrients above the RDA or AI levels. The Acceptable Macronutrient Distribution Range (AMDR) is a percent- age of energy intake for carbohydrates, proteins, and fats, including the linoleic and α -linolenic essential fatty acids,

that is associated with good health. For example, the AMDR for protein is 10% to 35%; that is, no less than 10% and no more than 35% of the total energy (calorie) intake should come from proteins. Finally, the DRI for total energy is the estimated energy requirement (EER). Food and supplement labels use the percent Daily Value (%DV), which is set by the Food and Drug Administration (FDA). The %DV tells the consumer what percent of an individual’s daily need for a given nutrient one serving of a food or supplement supplies. Because individuals of different age and sex have differ- ent nutrient needs, the percent of DV is intended to be used as an example. It is based on a 2,000-calorie diet. Calories Energy requirements are greater during growth peri- ods. Infants require approximately 115 kcal/kg of body weight at birth, 105 kcal/kg at 1 year of age, and 80 kcal/kg between 1 and 10 years of age. During adolescence, boys require 45 kcal/kg of body weight and girls require 38 kcal/kg. During pregnancy, a woman needs an extra 300 kcal/day above her usual requirement, and dur- ing the first 3 months of breast-feeding, she requires an additional 500 kcal. 5 Table 10-1 identifies the EER for healthy adults. 7 Proteins, Fats, and Carbohydrates Proteins, fats, and carbohydrates yield energy. They are referred to as macronutrients because the body requires them in relatively large amounts. Proteins. Proteins are required for growth and mainte- nance of body tissues, enzymes and antibody formation, fluid and electrolyte balance, and nutrient transport. Proteins are composed of amino acids, nine of which

TABLE 10-1 Estimated Energy Requirements (EER) at Different Activity Levels for Men andWomen 30Years of AgeWith a Normal (<25), Overweight (25 to 29.9), and Obese ( ≥ 30) BMI BMI Height m (in.) Weight kg (lb) Activity Level * EER (kcal/d) Male EER (kcal/d) Female

22.1

1.75 (69)

68

Rarely

2404 2627 2911 3378 2620 2867 3182 3698 2837 3108 3452 4018

2055 2285 2571 2915 2140 2380 2679 3038 2310 2570 2894 3284

Normal

(150)

Low activity

Active

Very active

26.5

1.75 (69)

77

Rarely

Overweight

(170)

Low activity

Active

Very active

31

1.75 (69)

95

Rarely

Obese

(210)

Low activity

Active

Very active

*Activity level definitions:  Sedentary = rarely exercises  Low active = less 1 hour/day  Active = about 1 hour/day  Very active = more than 1 hour/day

Developed using “Adult Energy Needs and BMI Calculator” from USDA/ARS Children’s Nutrition Center at Baylor College of Medicine. Available: http://www.bcm.edu/cnrc/caloriesneed.cfm. Accessed September 6, 2013.