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C H A P T E R 1 3 Nutrition for Older Adults  325

Lean Body Mass:          level represents the minimum protein intake necessary to avoid progressive loss of lean body
skeletal muscle and      mass as determined by nitrogen balance studies (Wolfe, Miller, and Miller, 2008). However,
bone mass.               the data were gathered almost entirely in college-aged men who can maintain nitrogen bal-
                         ance on less protein than can older adults (Wolfe et al., 2008). Physiologic changes and less
National Health          lean body mass in older adults leads to decreases in total body protein and contributes to
and Nutrition            increased frailty, impaired wound healing, and decreased immune function (Bernstein and
Examination Survey       Munoz, 2012). Evidence suggests that older adults need more protein than younger adults
(NHANES): a survey       and that a protein intake between 1.0 and 1.6 g/kg/day is safe and adequate to meet the
conducted by the         needs of healthy older adults (Houston et al., 2008). (See section on Sarcopenia.)
National Center for
Health Statistics de-         According to data from the National Health and Nutrition Examination Survey
signed to assess the     (NHANES) 2007–2008, mean protein intake exceeds the RDA for both men and women
health and nutritional   among all age groups, although a steady decline in intake occurs with aging (U.S. Department
status of adults and     of Agriculture [USDA], Agricultural Research Service [ARS], 2010). An estimated 7.2% to 8.6%
children in the United   of older adult women consume protein below their estimated average requirement (Fulgoni,
States via personal in-  2008). Factors that may contribute to a decrease in protein intake include the cost of high-
terviews and physical    protein foods, the decreased ability to chew meats, lower overall intake of food, and changes in
examinations.            digestion and gastric emptying (Paddon-Jones, Short, Campbell, Volpi, and Wolfe, 2008).

Water

                         The Adequate Intake (AI) for water, which includes total water from drinking water, other
                         beverages, and water in solid foods, is constant from 19 years of age through more than
                         70 years old, with 3.7 L/day of total water recommended for men and 2.7 L/day for
                         women (Institute of Medicine, 2005). Both of these figures represent a level of intake
                         necessary to replace normal daily losses and prevent the effects of dehydration (National
                         Research Council, 2005b). Like younger adults, the elderly are able to maintain fluid bal-
                         ance over a wide range of intakes.

                              Most older adults do not meet the recommended intake for water (Bernstein and
                         Munoz, 2012). A number of physiologic changes and other factors increase the risk of
                         dehydration in the elderly, including an impaired sensation of thirst, alterations in mental
                         status and cognition, adverse effects of medications, impaired mobility, and an age-related
                         decrease in the ability to concentrate urine. Fear of incontinence and pain from arthritis
                         may cause voluntary restriction in fluid intake. Dehydration can contribute to constipation,
                         cognitive impairment, functional decline, and death (Bernstein and Munoz, 2012).

Fiber

                         For all age groups, the AI for fiber is based on median intake levels observed to protect
                         against coronary heart disease (CHD) (National Research Council, 2005a). From the age
                         of 1 year on and for both genders, the AI for fiber is set at 14 g/1000 cal of intake. Based
                         on median calorie intakes, the AI for fiber is 38 g/day for men through age 50 years and
                         30 g/day thereafter. A similar decrease occurs in women, whose AI is 25 g/day from 19 to
                         50 years and 21 g/day thereafter.

                              Intake surveys consistently show that older adults consume approximately half the
                         recommended amount of fiber (USDA, ARS, 2010). Increasing fiber intake may help pre-
                         vent constipation, improve glycemic control, and reduce serum cholesterol levels (Bernstein
                         and Munoz, 2012).

Vitamins and Minerals

                             Most recommended levels of intake for vitamins and minerals do not change with aging.
                             Significant exceptions to this generalization are calcium and vitamin D and, for women, the
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