Nutrition in Older Adults1
Connie Watkins Bales
Mary Ann Johnson
1Abbreviations: AD, Alzheimer disease; AI, adequate intake; CHD, coronary heart disease; CKD, chronic kidney disease; CVD, cardiovascular disease; DRI, dietary reference intake; EAR, estimated average requirement; H2RA, histamine H2 receptor antagonist; IDA, iron deficiency anemia; NHANES, National Health and Nutrition Examination Survey; OAA, Older Americans Act; PPI, proton pump inhibitor; RDA, recommended dietary allowance; USDA, United States Department of Agriculture; VMS, vitamin and/or mineral supplement.
OVERVIEW
Between the years 2000 and 2050, the number of adults aged 60 years and older will double in the United States and more than triple worldwide (1, 2). The “graying” of the world’s population brings a considerable burden of chronic diseases, and many, if not most, of these diseases have a strong nutritional component. Thus, this chapter reviews the impact of diet on chronic health conditions and selected nutrients of concern as well as the infrastructure in the United States for meeting the food and nutrient needs of older adults in the continuum of care in community and long-term care settings. Although knowledge of how nutrition supports health throughout life is growing, much remains to be learned and applied in numerous areas, including the following: (a) the behavioral sciences, concerning ways to improve eating habits and thus lessen the burden of chronic disease; (b) the policy arena, to ensure that all older people have access to safe and nutritious foods at all times; and (c) the basic and clinical sciences, to delineate the role of specific foods and nutrients further in maximizing health and minimizing the adverse consequences of sarcopenia, weight loss, nutritional frailty, and other age- and nutrition-related concerns.
Current and Future Demographics of Aging
In 2009, 12.9% of the US population was at least 65 years of age; in several states, the proportion exceeded 15% (Florida, Maine, Pennsylvania, and West Virginia). On average, approximately 4.1% of older adults lived in institutional settings, but this number increased with age from 0.9% for those 65 to 74 years old, to 3.5% for those 75 to 84 years old, and to 14.3% for those 85 years old or older. An additional 2.4% lived in senior housing with at least one supportive service. Eleven states had more than 50% of the nation’s older adults, each with more than 1 million older people: California, Florida, Georgia, Illinois, Michigan, New Jersey, New York, North Carolina, Ohio, Pennsylvania, and Texas. Approximately 38.8% of older women and 18.7% of older men lived alone, and the proportion of persons living alone increased with advanced age. The median income of older adults was $25,877 for men and $15,282 for women in 2009, and approximately 8.9% were below the poverty level (10.7% of women and 6.6% of men) (3).
The number of individuals in the United States who are 65 years old and older will more than double from 40 million in 2010 to 88 million in 2050, whereas those aged 85 years old and older will increase by more than three-fold to 19 million (3). Ethnic and racial diversity is also increasing. Between 2010 and 2050, the number of older Hispanics will increase from 2.8 million to 17.5 million, whereas the number of older blacks will increase from 3.3 million to 9.9 million (3). In 2007, life expectancy in the United States at birth was 77.9 years; it was 30.9, 18.6, and 6.5 years at ages 50, 65, and 85, respectively (4). This population shift is a global phenomenon; in fact, the United States ranks only forty-ninth in life expectancy worldwide (5).
In summary, major demographic shifts will be associated with particularly large increases in the oldest old (>85 years of age) and of racial and ethnic minorities. These trends bring new challenges in health care, especially for preventive and therapeutic nutritional care for older adults.
Physiologic and Other Changes Affecting Nutritional Risk
Certain physiologic and metabolic changes inherent in the aging process have the potential to increase nutritional risk. The requirements for some, but not all, nutrients can be altered by these changes. Some of these factors and their potential influences on nutrient needs and intakes are shown in Table 56.1. Additionally, medical comorbidities and a host of other factors, including economic, geographic, and psychosocial concerns, can also affect diet behaviors and thus nutritional status.
Assessment of Nutritional Status
Nutritional screening and assessment should be part of the standard of care for all older adults (6). The goal of nutritional screening is to identify individuals who are at increased risk of being undernourished or malnourished. For those found to be at nutritional risk, a full assessment is warranted. Although biochemical indicators can signal a nutritional problem at the subclinical level, blood markers of nutritional status are far from specific. Serum albumin, the most commonly measured parameter, declines slightly with age (0.8 g/L/decade after age 60 years) and is influenced by a host of pathologic changes that are frequent in older adults, including chronic inflammation, advanced liver disease, heart failure, and nephrotic syndrome. Additionally, albumin is unlikely to be responsive to protein repletion in a timely manner (7).
Assessment of status for micronutrients is not routinely conducted unless a specific deficiency is suspected. Micronutrients most likely to be assessed in older persons include vitamins B12 (cobalamin concentration should be >350 pg/mL) and D 25[OH]D3; concentration should be >50 nmol/L or 20 ng/L) and markers of iron status (ferritin should be 12 to 300 ng/mL in men and 12 to 150 ng/mL in women; hemoglobin should be 14.0 to 17.5 g/dL in men and 12.3 to 15.3 g/dL in women.)
Proposed guidelines entitled “Adult Starvation and Disease-Related Malnutrition” from an international consensus guideline committee may also be applicable to older adults in the medical setting (8). The biochemical and body composition cut points are in development, but the guidelines propose that malnutrition can occur under different situations, requiring differing interventions: (a) pure chronic starvation without inflammation, (b) chronic disease or conditions that impose sustained inflammation to a mild to moderate degree, and (c) acute disease or injury states with a marked inflammatory response.
In the community setting and in long-term care, the challenge is to achieve early identification of risk factors and signs of impending problems relating to food intake so that appropriate interventions can be optimally effective.
A physical examination can reveal signs of clinical nutritional deficiencies, including skin changes, fatigue, weakness, changes in ability to taste or smell, and gastrointestinal complaints (poor appetite, oral problems, nausea, vomiting, diarrhea, constipation). Changes in mental or emotional status may also be associated with an inadequate nutritional state (9). However, the single most important clinical measure of undernutrition in older adults is that of current body weight and any recent changes. The Long-Term Care Minimum Data Set considers a weight loss of 5% of usual body weight in 30 days or 10% in 180 days as a trigger for activating clinical assessment protocols (10). Unintentional recent weight loss is associated with increased mortality (11). Even with a stable body weight, older adults may have a marked reduction in fat-free mass or increases in fat mass (12).
A physical examination can reveal signs of clinical nutritional deficiencies, including skin changes, fatigue, weakness, changes in ability to taste or smell, and gastrointestinal complaints (poor appetite, oral problems, nausea, vomiting, diarrhea, constipation). Changes in mental or emotional status may also be associated with an inadequate nutritional state (9). However, the single most important clinical measure of undernutrition in older adults is that of current body weight and any recent changes. The Long-Term Care Minimum Data Set considers a weight loss of 5% of usual body weight in 30 days or 10% in 180 days as a trigger for activating clinical assessment protocols (10). Unintentional recent weight loss is associated with increased mortality (11). Even with a stable body weight, older adults may have a marked reduction in fat-free mass or increases in fat mass (12).
TABLE 56.1 POTENTIAL PHYSIOLOGIC AND METABOLIC DETERMINANTS OF NUTRIENT NEEDS AND INTAKES IN OLDER ADULTS | ||||||||||||||||||||||||||||||
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Dietary assessments can be problematic in some older adults (13) because underreporting and memory problems may diminish accuracy. However, important questions about the number of meals eaten or skipped, the types and amounts of foods and nutritional supplements ingested, and potential barriers to consuming a nutritionally adequate diet can be very helpful in guiding subsequent interventions. Given the lack of any one gold standard measure of nutritional status, the use of indices that combine several variables is common. The best known of these indices intended for use in older adults is the Mini Nutritional Assessment (14). This validated tool has been widely used and shown to be predictive of adverse clinical events and mortality (15); a short version has also been validated (14).
Dietary Reference Intakes for Older Adults
Dietary recommendations for intakes of essential nutrients by age and gender are set by the Food and Nutrition Board of the Institute of Medicine. These recommendations, along with typical intakes of older adults, are shown in Table 56.2. Some dietary reference intake (DRI) recommendations are
higher for men compared with women, such as DRIs for protein, fiber, magnesium, zinc, vitamin B6, vitamin A, and vitamin K. DRI recommendations increase with age for vitamin D and decrease with age for sodium (16, 17).
higher for men compared with women, such as DRIs for protein, fiber, magnesium, zinc, vitamin B6, vitamin A, and vitamin K. DRI recommendations increase with age for vitamin D and decrease with age for sodium (16, 17).
TABLE 56.2 RECOMMENDATIONS AND INTAKES OF SELECTED NUTRIENTS FOR OLDER ADULTS (NHANES)a | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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As already indicated, a host of physiologic and psychosocial factors can influence food intake and determine whether diets consumed by older adults actually meet nutritional needs. As illustrated in Table 56.2, results of National Health and Nutrition Examination Survey (NHANES) surveys show that average intakes from diet alone exceeded recommendations for protein, fiber, sodium, iron, zinc, folate, vitamin B12, vitamin B6, and vitamin A. Nutrients for which dietary intakes were generally lower than recommendations included potassium, magnesium, calcium, and vitamins D and E. The intakes of most nutrients were consistently higher in persons 60 to 69 years old compared with those 70 years old or older, except for intakes of vitamin D, vitamin A, vitamin K, and “added” vitamin B12; however, vitamin D intakes remained much lower than recommendations for all age groups.
Dietary Guidelines for Older Americans
Along with the DRIs, the Dietary Guidelines for Americans are used to assist with meal planning for congregate and home-delivered meals and in institutional settings, as well as for general dietary guidance (18). Food-based recommendations at various energy intakes facilitate meal planning (e.g., the recommended servings of fruit, vegetables, whole grains, meat equivalents, and milk products). Specific recommendations relevant to older adults emphasize consuming “added” vitamin B12 from fortified foods or supplements and the health benefits of limiting sodium intake (to <1500 mg/day). Across the life span, the nutrients of concern were identified as vitamin D, calcium, potassium, and dietary fiber.
NUTRIENT-SPECIFIC CONCERNS IN OLDER ADULTS
Energy, Protein, Fiber, and Fluid
Energy requirements as well as intakes decrease with advancing age. A gradual reduction of approximately 7 and 10 kcal/year for women and men, respectively, occurs (19). Similarly, protein intakes decrease with age. However, the current recommended dietary allowance (RDA) for protein is not changed with age; it is 0.80 g/kg/day of high-quality protein (20). Most community-dwelling individuals are not at high risk for protein or protein-calorie malnutrition, but home-bound (21) and hospitalized older adults (see subsequent section) as well as nursing home residents are all at risk of protein insufficiency. Reduced food intake resulting from the anorexia of aging may also jeopardize the adequacy of protein and other essential nutrients. Frailty secondary to poor nutritional intake is addressed in a subsequent section.
Fiber intake is inversely associated with the risk of several age-related diseases; the adequate intake (AI) for fiber is based on prospective studies of fiber and coronary heart disease (CHD) (22). Although no tolerable upper intake limit (UL) for dietary fiber has been established, the functional fibers added to some foods, beverages, and supplements may increase the risk of adverse effects (22). The AI for total fiber is based on energy intake and not on age itself (22). Fiber intake is much lower than the AI, and fiber is considered a nutrient of concern (18). Fiber is only one of numerous factors related to constipation (23). Aging is associated with a shift toward less healthful intestinal microflora, so there is interest in how fiber, other dietary components, and probiotics influence intestinal health.
Appropriate hydration can be a challenge for older adults, with the most common concerns focused on risks for dehydration (24). More recently, however, the potential negative effects of excessive water consumption have also been noted, including dilutional hyponatremia (water intoxication) and increased nocturia (25). Consumption of six to eight glasses of fluid a day is likely adequate for healthy elderly people except during stressful situations that are likely to increase fluid loss (e.g., severely hot weather, heavy exertion) (26).
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