68: Defining Adequate Nutrition for Older Adults

Weight loss and malnutrition are common in older adults. Previous studies have reported that 17% to 65% of hospitalized geriatric patients and up to 59% of geriatric residents in institutions suffered from malnutrition. Over the past 15 years, however, obesity in older adults has increased. Despite an overall weight increase, obese older patients lose lean mass and remain at risk for functional decline and other medical complications much as do older adults with involuntary weight loss. There remains controversy regarding the appropriateness of advocating for weight loss in older adults with body mass index (BMI) greater than 35, which is discussed later in this chapter.

In general, body weight in men tends to increase from age 30–60, plateaus for the next 10–15 years, and then slowly declines. In women, the pattern of weight change is similar, except that changes occur approximately 10 years later in life. Lean body mass (primarily skeletal muscle) begins to decline by middle age as a result of many factors, including decreasing exercise and age-related declines in hormone levels (eg, testosterone, estrogen, and growth factors), metabolism, and muscle protein synthesis. Even during healthy aging, daily energy requirements decline with age. This is a result of decreases in muscle mass and decreases in physical activity. There are many formulas to estimate resting caloric needs (Table 68–1). All of these estimations should take into account activity levels and underlying illness severity.

Recommended dietary allowances (RDAs) of vitamins and minerals for geriatric patients are not significantly different from those for middle age adults (Table 68–2). Notable differences include recommendations for calcium and vitamin D intake. For men older than age 70 years, recommended calcium intake increases from 1000 mg/day to 1200 mg/day. For both men and women older than age 70 years, the recommended daily dosage of vitamin D (cholecalciferol) increases from 600 IU to 800 IU. Most nonprescription multivitamins provide adequate vitamins and minerals except for calcium and vitamin D. Supplementation with additional calcium and vitamin D remains warranted.

The RDA of macronutrients for older adults is similar to those for middle age adults (Table 68–3). Protein requirements are influenced by activity level, medications, nonprotein content of the diet, and health status. For example, corticosteroid use, bed rest, injury, infection, and inflammation all increase the risk of negative nitrogen balance, which can lead to rapid loss of lean body mass. Older hospitalized persons who are very ill or recovering from trauma or major surgery may require ≥1.5 g/kg per day of protein to maintain their nitrogen balance. Monitoring protein intake becomes challenging in medical conditions requiring protein restriction, such as liver or renal disease. In these situations, patients and families have to work closely with dietitians to provide adequate protein intake without worsening patients’ hepatic or renal failure.

Serum lipid levels remain a strong a predictor of risk for coronary heart disease in older adults as in middle-age adults. Most current recommendations for a healthy diet suggest a diet in which 25% to 30% of total calories come from fat. Some fat in the diet is required for the absorption of fat-soluble vitamins (A, D, E, and K). In addition, essential fatty acids must be consumed because they cannot be synthesized in the body. There are 2 general categories of essential fatty acids, which are omega-6 type and omega-3 type. Omega-6 fatty acids have proinflammatory properties and are the substrate for arachidonic acid, prostaglandins, thromboxanes, and leukotrienes. Omega-3 fatty acids, including eicosapentaenoic acid, docosahexaenoic acid, and prostacyclin, decrease platelet aggregation and vasoconstriction and have antiinflammatory properties. Based on current data, in nonfrail older adults, fat intake should not exceed 30% of total calories consumed, polyunsaturated and monounsaturated fats should predominate, and saturated fat and partially hydrogenated fat intake should be reduced. However, in those frail older adults who are at high risk for weight loss, fat intake of all types should be encouraged so as to increase total calorie intake.

Carbohydrate requirements are generally calculated after determining total caloric, fat, and protein requirements. Thus, carbohydrates generally make up approximately 55% of total caloric intake. Unrefined, whole-grain products should be emphasized, with decreased intake of simple sugars.

The DASH diet (Dietary Approaches to Stop Hypertension), which is a diet rich in fruits, vegetables, low-fat dairy, and <25% fat, is recommended to reduce blood pressure (http://dashdiet.org). Furthermore increasing whole-grain food intake improves fiber intake. A higher intake of fiber is associated with improved bowel function and is associated epidemiologically with a decreased risk for cardiovascular disease, diverticular disease, and diabetes mellitus type 2. Supplementing the diet with commercially available concentrated fiber sources may be necessary when fiber intake from natural sources is inadequate. Fiber intake should be increased gradually to avoid bloating, excess flatus, and general discomfort. Adequate fluid intake is also needed, particularly with bed-bound or inactive persons, because constipation may actually worsen with fiber alone.

Anthropometrics

Adverse effects of unintentional weight loss and malnutrition—

Among community-dwelling older adults, significant weight loss is defined as 4% to 5% weight loss over 6–12 months or rapid weight loss of >5% in 1 month. For older adults living in skilled nursing homes, the definition of significant weight loss is either ≥10% weight loss over 180 days or ≥5% weight loss over 1 month. Some of the adverse effects of involuntary weight loss and malnutrition include functional decline, increase in mortality rate (9% to 38% within 1–2.5 years), increased risk for hospitalization, increased risk for developing pressure ulcers, postural hypotension, poor wound healing, cognitive decline, and increased risk for infection as a result of poor immune function. Physical signs of malnutrition besides weight loss include peripheral edema caused by protein malnutrition, alopecia, glossitis, skin desquamation, and dry depigmented hair.

Adverse effects of obesity in older adults—

In the United States, approximately 42.5% of women 60–79 years old and 19.5% of women older than age 80 years are obese (BMI >30). For men, 38.1% between ages 60 and 79 and 9.6% of men older than age 80 years are obese. Obesity is associated with an increase in all-cause mortality rate in community-dwelling older adults. However, for geriatric patients living in skilled nursing homes, increase in mortality was found for BMI ≥35 but not for those with BMI between 30 and 35. Obesity can increase the risk for developing hypertension, dyslipidemia, diabetes mellitus, coronary artery disease, stroke, osteoarthritis, and sleep apnea. Increased risk for breast, prostate and colon cancers have also been associated with obesity. Also, obesity has been associated with increased knee pain from osteoarthritis.

BMI, rather than body weight, is a better measure for determining an individual’s nutritional status. BMI adjusts weight in relation to height; however, it does not identify persons who have replaced muscle mass with adipose tissue, nor does it distinguish persons with central obesity. Central obesity is associated with negative health outcomes and thus some researchers believe that waist circumference may be a better measure than BMI for assessment of obesity in older adults.

Skinfold measurement using calipers are prone to many measurement errors and remain primarily a research tool. Bioelectric impedance may prove a better way to assess body composition; however, it is influenced by volume status and also mostly used in research.

Laboratory Assessment

The initial laboratory assessment of weight loss should include a complete blood count, glucose, electrolytes, renal and liver function, thyroid-stimulating hormone level, urinalysis, and chest x-ray film. These initial tests should rule out metabolic, endocrine, or infectious causes of weight loss.

Although serum albumin is commonly ordered to assess protein nutrition or status, serum albumin levels have poor sensitivity and specificity as a measure of nutritional health. The half-life of albumin is approximately 3 weeks. Levels respond slowly to adequate nutritional intervention and may never normalize if inflammation is ongoing. Raising the serum albumin with intravenous albumin replacement does not improve prognosis. However, measurement of serum albumin does have clinical value: A low serum albumin, although not a good indicator of nutritional status, may be a powerful predictor of illness severity and mortality.

Prealbumin (transthyretin) has a short half-life of 2–3 days and is more sensitive than albumin in evaluating acute nutritional change. A low level can be used to confirm the clinical impression of poor nutritional status in the absence of inflammation. A progressively rising prealbumin level may help to confirm improving nutritional status; however, the clinical exam remains the best indicator. Serum cholesterol <160 mg/dL is a marker for increased risk of morbidity and mortality but not a good measure of nutrition.

Clinical Assessment

A comprehensive clinical assessment of nutritional status is the most useful way to identify malnutrition, and several assessment instruments exist. The Mini-Nutritional Assessment (Figure 68–1) has become widely used to evaluate nutritional status in geriatric patients. Other screening tools include Seniors in the Community: Risk Evaluation for Eating and Nutrition (SCREEN) (http://www.drheatherkeller.com/index.php/screen/) and the Simplified Nutrition Assessment Questionnaire (SNAQ) (http://www.slu.edu/readstory/newslink/6349).

Potential Causes of Unintentional Weight Loss

As in most geriatric syndromes, unintentional weight loss in older adults is often caused by multiple factors. Possible causes can be categorized into medical, psychosocial, and pharmacologic (Table 68–4). Underlying or previously undiagnosed cancer could be the cause of involuntary weight loss in 16% to 36% of cases according to some studies. Gastrointestinal malignancy such as esophageal, pancreatic, and gastric cancer is more common than other cancers. Other malignancies that are associated with weight loss include lymphomas, and lung, prostate, ovarian, and bladder cancers. Nonmalignant causes of weight loss include chronic illnesses such as dementia, congestive heart failure, chronic obstructive pulmonary disease, endocrine disorders (diabetes mellitus, hyperthyroidism), and end-stage kidney or liver failure. Oral and dental problems, such as ill-fitting dentures or poor dentition, can also lead to weight loss.

Social factors, such as financial constraints, inability to shop or cook, social isolation, and lack of ethnic foods in an institutional facility, can contribute toward unintentional weight loss. Depression and dementia are major causes of weight loss in older adults, and may account for 10% to 20% of weight loss in community-dwelling older adults and in 58% of nursing home residents. People who have dementia lose weight and decrease food intake as a result of dysphagia, the inability to self-feed, and the excess energy expenditure caused by agitation and wandering. Many medications can lead to weight loss from side effects of anorexia, nausea/vomiting, dry mouth, or altered taste or smell (see Table 68–4).

Improve Malnutrition and Weight Loss

Patients often eat better, and more, when fed by family members. One reason for this is the length of time the family member dedicates to unhurriedly feeding and encouraging the patient. Older people also eat more if they are eating with others. Studies have shown that older adults receiving meals-on-wheels eat more if the delivery person stays with them. Successfully motivating undernourished persons to eat requires a multidimensional approach, including treating pain, increasing social supports, and adapting to individual food preferences and meal times. Simple exercise, such as daily walking, may improve appetite in some patients. As stated above, depression is a common cause of anorexia and refusal to eat. Patients should be screened for depression and if needed, referred for evaluation by a psychiatrist or psychologist.

Oral supplements—

A variety of commercial liquid and powder supplements are used when patients are unable or unwilling to consume enough regular food. Although the most recent Cochrane review on oral nutritional supplements did not show improvement in survival rate, studies using dietary advice with or without oral nutritional supplements have shown improvement in weight and body composition. Nutritional supplements are most effective when consumed at least one hour before meals, so patients do not substitute supplement intake for regular meals. Powder formulations allow the supplement to be masked by mixing it with other food. A major barrier to canned supplements is cost, even with generic brands. For patients with no history of lactose intolerance, instant breakfast powders mixed in milk are a satisfactory and less-expensive alternative.

Appetite stimulants—

Several medications have been promoted as helping to improve appetite and increase weight; however, none have proven satisfactory in geriatric patients. Megestrol acetate has been shown to increase appetite and weight in AIDS and cancer patients and to increase weight in older adults. Recent studies, however, have shown that megestrol acetate increases adipose tissue rather than lean mass, increases the risk for thromboembolic disease and suppresses the hypothalamic pituitary adrenal axis. Several small clinical trials with dronabinol in older adults showed that they were unable to tolerate the dysphoria associated with dronabinol use. Cyproheptadine has not been shown to be effective in older adults. Anabolic agents such as growth hormone and insulin-like growth factor are expensive and associated with frequent side effects. Ghrelin use in clinical trials has increased body weight and lean body mass in older adults; however, it is currently only available for research purposes. Androgen therapy with testosterone or its analogues also has many side effects, and thus its use for weight gain remains experimental. Antiinflammatory therapies that affect arachidonic acid metabolism and cytokine release, including the omega-3 fatty acids, are also being studied. Persons with persistent anorexia may benefit from a trial of antidepressant therapy such as with mirtazapine.

Artificial tube feeding—

Before discussing use of artificial tube feeding, patients and their family members should discuss overall goals of care. In certain cases, temporarily use of tube feeding can be beneficial, such as during treatments for head neck cancer or recovery from an acute stroke. Some clinicians initiate artificial feeding as a therapeutic trial for a limited and predetermined duration with the understanding that if certain goals are not achieved (eg, the person will begin to voluntarily consume sufficient calories for survival), the intervention will be discontinued. (For more on the use of feeding tubes, see Chapter 11, “Geriatrics & Palliative Care.”)

Previous studies have shown that for patients with end-stage dementia, initiation of artificial tube feeding neither increases survival nor improves function. Furthermore, no method of tube feeding (G-tube or J-tube) will prevent aspiration or pneumonia.

Treatment of obesity—

Community-dwelling older adults who are obese and have poorly controlled hypertension, diabetes mellitus, functional impairment, or lower-extremity arthritis may benefit from gradual weight reduction. Sustained weight loss generally requires a combination of healthy diet and exercise. Several studies of older obese adults who were placed on a weight loss diet along with exercise (aerobic exercise and resistance training) demonstrated ability of these subjects to lose weight without losing significant lean body mass. The use of weight loss medication (amphetamines, sibutramine, orlistat) in older adults has not been investigated adequately and thus these medications should not be used or should be used with significant caution. Amphetamines and sibutramine should be avoided in patients with cardiac disease.

Although the effects of obesity have been studied extensively in older adults living in the community, little is known about the effects of obesity in the nursing home. One study showed that nursing home residents with BMI >40 kg/m² were associated with increased mortality compared to those with normal weight (BMI of 19–28). Because of concerns about potential malnutrition and decrease in bone density, weight loss programs for nursing home residents should be initiated with caution. Having a low BMI (<19 kg/m²) is associated with increased mortality rates among nursing home patients, and nursing home residents with a BMI of 30–35 have been shown to have a higher mortality rate.

Interaction between medications and food

—Certain foods can inhibit or potentiate the effects of commonly prescribed medications for older adults (Table 68–5). Grapefruit juice can inhibit the cytochrome P450 3A4 and thus lead to increased serum levels of statins, calcium channel blockers, and phosphodiesterase inhibitors (sildenafil, vardenafil and tadalafil) (Table 68–5). Dairy products or calcium supplements can diminish the effectiveness of some antibiotics (fluoroquinolones, cefuroxime, tetracyclines) if taken together (Table 68–5). These antibiotics should be taken at least 2 hours before or 6 hours after calcium supplements or calcium-rich foods. For community-dwelling older adults, their local pharmacist is often a good person to consult for how many hours to wait until a food or drink can be consumed after taking a medication. Table 68–5 lists other interactions between food and medications.

The RDAs of vitamins, minerals and macronutrients for geriatrics patients are not significantly different for younger adults except for increased need for calcium and vitamin D supplements. The DASH diet may serve as a good guideline for healthy older adults to follow. Involuntary weight loss and obesity in older adults can increase morbidity and mortality. Improving malnutrition and weight loss in geriatric patients probably will require multistep approach. Reassessment of social issues, potential psychiatric illness, underlying medical conditions and medications is essential. A combination of healthy diet and exercise should be recommended for obese community dwelling older adults. For obese nursing home residents, weight loss programs should be initiated with caution.