Chapter 070. Nutritional Requirements and Dietary Assessment (Part 2) Water For adults, 1.0–1.5 mL water per kcal of energy expenditure is sufficient under usual conditions to allow for normal variations in physical activity, sweating, and solute load of the diet. Water losses include 50–100 mL/d in the feces, 500–1000 mL/d by evaporation or exhalation, and, depending on the renal solute load, ≥1000 mL/d in the urine. If external losses increase, intakes must increase accordingly to avoid underhydration. Fever increases water losses by approximately 200 mL/d per °C; diarrheal losses vary but may be as great as 5 L/d with severe diarrhea. Heavy sweating and vomiting also increase water losses. When renal function is normal and solute intakes are adequate, the kidneys can adjust to increased water intake by excreting up to 18 L/d of excess water (Chap. 334). However, obligatory urine outputs can compromise hydration status when there is inadequate intake or when losses increase in disease or kidney damage. Infants have high requirements for water because of their large ratio of surface area to volume, the limited capacity of the immature kidney to handle high renal solute loads, and their inability to communicate their thirst. During pregnancy, 30 mL/d additional water is needed. During lactation, milk production increases water requirements by approximately 1000 mL/d, or 1 mL for each mL of milk produced. Special attention must be paid to the water needs of the elderly, who have reduced total body water and blunted thirst sensation, and may be taking diuretics. Other Nutrients See Chap. 71 for a detailed description of vitamins and trace minerals. Dietary Reference Intakes and Recommended Dietary Allowances Fortunately, human life and well-being can be maintained within a fairly wide range for most nutrients. However, the capacity for adaptation is not infinite—too much of a nutrient, as well as too little, may have adverse effects on health. Therefore, quantitative benchmark recommendations on nutrient intakes have been developed to guide clinical practice. These estimates are collectively referred to as the dietary reference intakes (DRIs). The DRIs supplant but include the recommended dietary allowances (RDAs), the single reference values used in the United States since 1989. DRIs include the estimated average requirement (EAR) of a nutrient, as well as three other reference values used for dietary planning for individuals: the RDA, or, if it cannot be established, the adequate intake (AI), and the tolerable upper level (UL). The current DRIs for vitamins and elements are provided in Tables 70-1 and 70-2, respectively. Table 70-1 Dietary Reference Intakes: Recommended Intakes for Individuals—Vitamins Vitamin, µg/d ife- Stage Grou p a b,c d hiami ne, mg/d ibofla vin, mg/d iacin , mg/ d e itami n B 6 , mg/d olat e, µg/d f itami n B 12 , µg/d P antoth enic Acid, mg/d iotin , µg/d holin e, mg/d g nfants 1 0–6 mo 00 0 .0 .2 .3 .1 5 .4 .7 25 7–12 mo 00 0 .5 .3 .4 .3 0 .5 1 .8 50 hildre n 1–3 y 00 5 0 .5 .5 .5 50 .9 2 00 4–8 y 00 5 5 .6 .6 .6 00 .2 3 2 50 ales 4 9–13 y 00 5 1 0 .9 .9 2 .0 00 .8 0 75 14– 18 y 00 5 5 5 .2 .3 6 .3 00 .4 5 5 50 19– 30 y 00 0 5 20 .2 .3 6 .3 00 .4 5 0 50 31– 50 y 00 0 5 20 .2 .3 6 .3 00 .4 5 0 50 51– 70 y 00 0 0 5 20 .2 .3 6 .7 00 .4 h 5 0 50 >70 y 00 0 5 5 20 .2 .3 6 .7 00 .4 h 5 0 50 emale s 9–13 y 00 5 1 0 .9 .9 2 .0 00 .8 4 0 75 14– 18 y 00 5 5 5 .0 .0 4 .2 00 i .4 5 5 00 19– 30 y 00 5 5 0 .1 .1 4 .3 00 i .4 5 0 25 31– 50 y 00 5 5 0 .1 .1 4 .3 00 i .4 5 0 25 51– 70 y 00 5 0 5 0 .1 .1 4 .5 00 .4 h 5 0 25 >70 y 00 5 5 5 0 .1 .1 4 .5 00 .4 h 5 0 25 regna ncy ≤18 y 50 0 5 5 .4 .4 8 .6 00 j .6 6 0 50 19– 30 y 70 5 5 0 .4 .4 8 .9 00 j .6 6 0 50 31– 50 70 5 5 0 .4 .4 8 .9 00 j .6 6 0 50 y actati on ≤18 y 200 15 9 5 .4 .6 7 .0 00 .8 7 5 50 19– 30 y 300 20 9 0 .4 .6 7 .0 00 .8 7 5 50 31– 50 y 300 20 9 0 .4 .6 7 .0 00 .8 7 5 50 . Chapter 070. Nutritional Requirements and Dietary Assessment (Part 2) Water For adults, 1.0–1.5 mL water per kcal of energy. thirst sensation, and may be taking diuretics. Other Nutrients See Chap. 71 for a detailed description of vitamins and trace minerals. Dietary Reference Intakes and Recommended Dietary Allowances. Infants have high requirements for water because of their large ratio of surface area to volume, the limited capacity of the immature kidney to handle high renal solute loads, and their inability