Geriatric nutrition applies nutrition principles to delay effects of aging and disease, to aid in the management of the physical, psychological, and psychosocial changes commonly associated with growing old.
The number of people over 65 years of age jumped from 4% of the U.S. population in 1900 to 13% in 1990, and is expected to reach 20% in 2030, due primarily to advances in health care. "Elderly" was once defined as being age 65 or above, but the growing number of active and healthy older people has caused that definition to expand to "young old" (65 to 75), "old old" (75 to 85), and "oldest old" (85 and beyond). The over-85 age group is the one that is growing most rapidly.
The cornerstone of geriatric nutrition is a well-balanced diet. This provides optimal nutrition to help delay the leading causes of death: heart disease, cancer, and stroke. In addition, ongoing research indicates that dietary habits, such as restricting one's calorie intake and consuming antioxidants, may increase longevity.
With age comes many physical changes. Once the body reaches physiologic maturity, the rate of degenerative change exceeds the rate of cell regeneration. However, people age at different rates, so the elderly population is not a homogeneous group; there is great variability among individuals.
The following are typical physiologic changes that can affect nutritional status:
- Body composition changes as fat replaces muscle, in a process called sarcopenia. Research shows that exercise, particularly weight training, slows down this process. Because of the decrease in lean body mass, basal metabolic rate (BMR) declines about 5% per decade during adulthood. Total caloric needs drop, and lowered protein reserves slow the body's ability to respond to injury or surgery. Body water decreases along with the decline in lean body mass.
- Gastrointestinal (GI) changes include a reduction in digestion and absorption. Digestive hormones and enzymes decrease, the intestinal mucosa deteriorates, and the gastric emptying time increases. As a result, two conditions are more likely: pernicious anemia and constipation. Pernicious anemia may result because of hypochlorhydria, which decreases vitamin B12 absorption and affects approximately one third of older Americans. Constipation, despite considerable laxative use among older people, may result from slower GI motility, inadequate fluid intake, or physical inactivity.
- Musculoskeletal changes occur. A progressive drop in bone mass starts when people are in their 30s or 40s; this accelerates for women during menopause, making the skeleton more vulnerable to fractures or osteoporosis. Adequate intake of calcium and vitamin D helps to retain bone.
- Geriatric nutrition must take into account sensory and oral changes. Decreases in all the senses, particularly in the taste buds that affect perception of salty and sweet tastes, may affect appetite. Xerostomia, lack of salivation, affects more than 70% of the elderly. Also, denture wearers chew less efficiently than those with natural teeth.
- Other organ changes may occur. Insulin secretion is decreased, which can lead to carbohydrate intolerance, and renal function deteriorates in the 40s for some people.
- Cardiovascular changes may occur. Reduced sodium intakes become important, as blood pressure increases in women over age 80 (but, interestingly, it declines in older men). Serum cholesterol levels peak for men at age 60 but continue to rise in women until age 70.
- Immunocompetence decreases with age. The lower immune function means less ability to fight infections and malignancies. Vitamin E, zinc, and some other supplements may increase immune function.
- Depression, the most common cause of unexplained weight loss in older adults, occurs in approximately 15% of adults over age 65, with a much higher incidence in those living in extended-care facilities.
- Memory impairment caused by various types of dementia, Alzheimer's disease, or other neurological diseases rises dramatically, with half of all persons over age 85 affected. Weight loss and improper nutrition are potential problems.
- Alcohol abuse is often unreported, especially since approximately one third of alcoholics age 65 years or older begin drinking later in life. Excessive alcohol intake (over 15% of total calories) increases morbidity and mortality, and leads to both physical and psychosocial problems.
- Social isolation becomes more common because of declining income, health problems, loss of spouse or friends, and assistance needs. All of these may affect appetite and possibly nutritional status.
Basic energy and nutrient needs
Calorie requirements decrease with age, although individuals vary greatly depending on their activity level and health status. Diets that fall below 1,800 calories a day may be low in protein, calcium, iron, and vitamins, so should feature nutrient-dense foods.
Protein needs of healthy older adults are the same as for other adults, with 0.8 to 1 gm of protein per kg of body weight recommended. Most older people without debilitating disease eat adequate protein, but those with infections or severe disease may become protein-malnourished due to increased protein requirements and poor appetites. Seniors do better eating more complex carbohydrates, which increase fiber, vitamins, and minerals, and help with insulin sensitivity. Lactase-treated milk or fermented dairy products are suggested if lactose intolerance develops. Because caloric needs drop and heart disease is so prevalent, reducing total dietary fat and especially the amount of saturated fats is advised.
Mineral deficiencies are uncommon in older adults, and recommended amounts are the same or similar to those for younger adults. Iron-deficiency anemia related to nutrition is rare, and more likely due to blood loss. Of the vitamins, vitamin D intakes are often lower than recommended, especially among homebound or institutionalized people who lack sun exposure (the most accessible source of vitamin D). The antioxidant vitamins, vitamin E, carotenoids, and vitamin C, continue to receive attention because of their potential to improve immune function and ward off disease. Requirements for riboflavin, vitamins B6 and B12, and zinc are increased in the elderly. However, needs for vitamin A decrease.
The incidence of dysphagia, or difficulty in swallowing, increases with age. Dysphagia results from conditions
Dehydration is the most common cause of fluid and electrolyte disturbances in older adults. Reduced thirst sensation and fluid intake, medications such as diuretics and laxatives, and increased fluid needs during illness contribute to dehydration. Adequate water-intake guidelines are 1 ml water/kcal energy consumed (for example, 1.8 L for an 1,800-calorie intake), or 25–30 ml/kg of weight for most individuals.
Skin breakdown is a common problem, particularly in bedridden or immunologically impaired people. The most common skin breakdown is the pressure ulcer, which occurs in 4% to 30% of hospitalized patients and 2% to 23% of residents of skilled-care nursing homes.
Pressure ulcers are graded or staged to classify the degree of tissue damage. Those with more serious Stage II to Stage IV ulcers have increased nutritional needs. Protein needs increase to 1–1.5 gm protein/kg, caloric needs increase to 30–35 kcal/kg, and 25–35 cc fluid/kg is recommended.
While most elderly people maintain adequate nutritional status, institutionalized and hospitalized older adults are at higher risk for malnutrition than individuals who are living independently. Cancer cachexia, the weak, emaciated condition resulting from cancer, accounts for about half of malnutrition cases in institutionalized adults.
Two common forms of malnutrition are protein-calorie malnutrition, in which the person appears illnourished; and protein malnutrition, in which an overweight person may have depleted protein stores. Nutrition support may involve higher protein and calorie amounts, nutritional supplements such as Ensure, or enteral tube feedings that provide nutrient solutions into the GI tract.
The following are used to assess nutritional needs:
- A thorough medical history, physical examination, and dietary history can provide a general picture of the individual's nutritional status. Lab values also provide valuable information.
- Weight evaluation may be recommended. Normal weight status guidelines include a BMI of 21 to 27 (BMI = weight in pounds x 704.5/ht(in) squared) or Ideal Body Weight +/-10%. Guidelines for significant weight loss include 10% weight loss in six months, 5% in one month, or 2% in one week.
- Dehydration evaluation involves physical assessment (poor skin turgor, dark urine, flushed skin), and assessment of recent fluid and food intake. High laboratory levels of blood urea nitrogen (BUN), albumin, serum sodium, and serum osmolality can indicate dehydration.
Laboratory values, particularly albumin for protein status and sodium and BUN for hydration status, should continue to be assessed after treatment. Tube feedings need to be continually monitored to prevent aspiration.
Normal laboratory values in the elderly
- Protein status: albumin 4 to 6 gm/dL; prelabumin: 19 to 43 mg/dL.
- Anemia status: hemoglobin: 12 to 18 gm/dL; hematocrit 33% to 49% (can be slightly lower in the elderly); MCV: 80 to 95 [.mu]m3; MCHC: 27 to 31 pg; B12: 100 to 1,300 pg/mL.
- Hydration: serum sodium: 135 to 147mEq/L; serum osmolality: 285 to 295 mOsm/kg; BUN 10 to 20 mg/dL (can be slightly higher in elderly).
Health care team roles
- Registered dietitians play the primary role in assessing and coordinating geriatric nutrition care.
- Nursing staff also assesses patients, and physicians oversee total care and ordering of lab tests.
- A speech-language therapist typically conducts a swallowing assessment and coordinates care for dysphagia.
Hypochlorhydria—A deficiency of hydrochloric acid in the gastric juice.
Pressure ulcer—Any lesion caused by unrelieved pressure resulting in damage to the underlying tissue.
Sarcopenia—A deficiency of muscle or flesh that occurs in the elderly.
Litchford, M. Clinical Geriatric Nutrition. Mary Litchford/Nutrition Dimension, Inc. 1999.
Mahan, L. K., and S. Escot-Stump. Krause's Food, Nutrition, & Diet Therapy, pp. 287-308. Philadelphia: W. B. Saunders Company, 1996.
American Dietetics Association. Nutrition, Aging and the Continuum of Care: Position of ADA. <http://www.eatright.org>.
Washlien, C. Nutrition and the Elderly Course, U. of Hawaii-Manoa, School of Public Health, 2000.
Linda Richards, R.D., C.H.E.S.