Malnutrition is associated with many chronic diseases of aging. The term malnutrition refers to both undernutrition (eg, unintended weight loss) and overnutrition (eg, obesity). Age-related changes in physiology, metabolism, and function also alter the nutritional requirements of older adults. Older adults can improve their health and independence by understanding the relationship between the aging process and nutritional screening, evaluation, and dietary management.
Changes Related to Age
Body composition
Aging is associated with changes in body composition, including bone mass, muscle mass, and water content. Total body fat increases, especially in the abdomen, while muscle and bone both decrease. The aging process also affects organ functions, although the degree of change varies from person to person. This decline in organ function may in turn affect nutritional status. This means that well-standardized nutrient requirements for younger or middle-aged adults cannot be generalized to older adults.
Energy requirements
Level of physical activity is an important factor in our daily energy needs. Activity level is one part of the "basal metabolic rate," which primarily determines how much energy we use each day. In general, basal metabolic rate decreases as we age, so that we need fewer calories each day to maintain normal weight. Unfortunately, many aging adults are still unable to meet these reduced energy needs. In various studies, up to 40% of the older adults had an energy intake less than one-third of the recommended daily allowance, and many older adults reported skipping at least one meal each day.
A simple method for estimating total daily energy needs is based on body weight. In general, an older adult needs to take in 25-30 calories per kilogram (ie, about 12-15 calories per pound) of "normal" body weight. It is important to remember that the definition of "normal" weight refers to the weight that you should be, not your current weight. "Normal" weight would be less than the current weight of a heavy or obese person, but more than the current weight of a thin person.
Types of food
When deciding the types of food to eat, older adults can follow the traditional US Department of Agriculture Food Guide Pyramid, with a few changes for the special nutritional needs of older adults 70 years old and older. For example, older adults may need supplemental calcium, vitamin D, and vitamin B12. In addition, most healthy older adults have lower caloric needs (1,600 calories or less a day) than when they were younger. Taking in enough fiber also becomes more important as we age.
Protein
The protein needs of healthy older adults may be somewhat higher than was once thought. People 51 years old and older should have 1.0 gram of protein per kg (about 0.5 grams per pound) of body weight every day. The protein requirement is even higher for some people. For example, protein requirements increase about 50% with stress or injury. In contrast, in some diseases, such as kidney or liver disease, protein intake should be restricted. In any case, you should discuss your daily protein intake with your healthcare provider before making any major changes.
Some proteins in the blood, such as albumin, can be used to estimate nutritional status. Low albumin levels have been associated with disease, a loss of function, muscle wasting, increased healthcare use, and even death. However, in any particular person, it can be difficult to know whether low albumin levels actually reflect poor nutrition, or if they simply indicate disease states or organ dysfunction.
Fats and carbohydrates
The USDA Dietary Guidelines for Americans suggest that no more than 30% of total energy should come from fat (for all age groups). Fat insulates and protects the body, and serves as a source of energy and essential fatty acids. It also carries the fat-soluble vitamins (eg, vitamins A, D, E, and K) around the body.
Cholesterol has also been linked to nutritional status. People with serious underlying disease, such as cancer, often have low cholesterol levels (<160 mg/dL). However, similar to low albumin levels, low cholesterol levels may be a nonspecific indicator of poor health, rather than a reflection of poor nutritional status.
Carbohydrates are a major source of energy for the body. They also provide fiber in the diet. About 55%-60% of the total calories we eat every day should come from carbohydrates. Complex carbohydrates like a starch (eg, pasta) are good sources.
Vitamins and minerals
Older adults have different vitamin and mineral requirements than younger people. Your healthcare provider or a nutritionist can advise you on the levels you need.
Fluid needs
Dehydration is the most common fluid problem in older people. As we age, our body loses some of its ability to regulate fluid levels. Our sense of thirst is also often reduced, so older people tend to drink less. Some conditions also reduce our ability to recognize that we are thirsty and need more fluid. It is common to need more fluid than usual during fever or infection, as well as when taking diuretic or laxative medications. Common signs of dehydration are less urine output, low-grade fevers, constipation, dry gums, and possibly confusion.
In general, older adults need to take in one ounce (ie, 30 mL) of fluid per kg (about half an ounce per pound) of body weight per day. For example, a 150-pound person needs 75 ounces of fluid every day. Ways to take in fluid include drinking liquids (nonalcoholic) or eating moist foods such as fruits and vegetables. If we are over- or under-hydrated (by taking in too much or not enough fluid), the results of clinical tests may be affected and result in an inaccurate assessment of health status.
Nutritional Screening and Evaluation
Monitoring weight is a large part of evaluating nutritional status in older adults. In general, an older person who unintentionally loses 10 pounds or more in the past 6 months is at risk of malnutrition. A similar guideline, used by Medicare-certified nursing homes, is weight loss of 5% or more in the past month or 10% or more in the past 6 months. This degree of weight loss increases risk of functional limitations, increased healthcare costs, and need for hospitalization.
Body mass index (BMI) is also sometimes used to estimate body size and nutritional status. Your BMI is defined as your body weight in kilograms divided by your height in meters squared (kg/m2). A BMI below 18.5 kg/m2 suggests underweight nutritional status, while a BMI above 30 kg/m2 suggests obesity (see Related Resources for more information on BMI).
Another way that inadequate nutritional intake has been defined is as an average or usual intake of food-group servings, nutrients, or energy below a threshold level of the recommended daily allowance (RDA). These screening thresholds have generally been set at 25% to 50% below the RDA, because it is difficult to accurately assess dietary intake and because actual need varies somewhat from person to person. Older adults with daily intakes at or below screening thresholds should be further evaluated for malnutrition and other underlying disease.
Drug-nutrient interactions
Some drugs can modify the nutrient needs and metabolism of older people. For example, certain drugs (eg, theophylline and digoxin) can cause loss of appetite and weight loss. Also, many drugs reduce the availability of specific nutrients to the body, so that a nutrient deficiency can develop even in the face of normal intake. Make sure you let you healthcare provider know all the medications you are taking, including over-the-counter compounds, so that any drug-nutrient interactions can be identified and corrected if needed.
Tools for nutrition screening
Nutritional status can be influenced by a variety of factors, which can't be measured by any one method of assessment. So, researchers have developed questionnaires that can be used to assess many factors simultaneously. Healthcare providers are beginning to use these questionnaires for a variety of purposes. However, we don't yet know whether such questionnaires are effective in identifying undernourished individuals whose problems can be successfully treated.
Risk Factors for Poor Nutritional Status
- Alcohol or substance abuse
- Cognitive dysfunction
- Decreased exercise
- Depression, poor mental health
- Functional limitations
- Low income
- Limited education
- Limited mobility, transportation
- Medical problems, chronic diseases
- Medications
- Teeth problems
- Restricted diet, poor eating habits
- Social isolation
Checklists have been developed to raise public awareness about the importance of nutrition in the health of older adults. For an example of a nutritional health checklist, see Related Websites. People who have poor scores should visit their healthcare provider for further evaluation. More sophisticated checklists are available for use by healthcare professionals, and include additional items on dietary habits, functional status, living environment, weight change, etc, and can be used as an aid in the diagnosis of malnutrition.
Nutrition Syndromes
Obesity
Obesity has been defined as a body mass index (BMI) >30 kg/m2. The prevalence of obesity in the US has climbed from 14.1% to 22.5% over the past several decades. This growing prevalence of obesity in America includes people in their 60s and 70s. Many problems are associated with obesity, including diabetes, heart disease, arthritis, impaired functional status, increased health care use, and early death.
Potential risks and benefits should be evaluated carefully in obese individuals to guide weight management. The focus must be on achieving a healthier weight to promote improved health, function, and quality of life. A combination of prudent diet, changes in behavior, and activity or exercise may be appropriate.
Sarcopenia
A loss of skeletal muscle mass that is related to age is called sarcopenia. The relationship between sarcopenia and functional limitation is unknown. It is also not known if some degree of sarcopenia is a normal part of aging or is a reflection of other factors, such as undernutrition or a sedentary life style. Possible causes include age-related muscle, nerve, or hormonal changes. However, loss of muscle mass with age can be reduced with good nutrition and vigorous exercise, while sedentary people lose muscle mass more rapidly as they age.
Cachexia and Wasting
The terms cachexia and wasting have been used to describe individuals with severe weight loss and/or diminished nutritional intake. Cachexia or wasting is characteristically seen in patients with rheumatoid arthritis, heart failure, chronic obstructive pulmonary disease, AIDS, cancer, some organ failure syndromes (eg, kidney, liver, lung), and certain critical injuries. In patients with cancer, AIDS, and organ failure syndromes, wasting is associated with a poor prognosis. Although nutritional supplementation and administration of appetite-stimulating agents can be helpful, it is most important to address the underlying disease process.
Other conditions
Other nutritional syndromes include protein-energy undernutrition (PEU) and "failure to thrive." Perhaps a third of older adults in hospitals or nursing homes are affected by PEU. Treatment has generally focused on nutritional support, but identifying and treating any underlying disease must be a priority. Failure to thrive is a term originally used to describe underdeveloped infants, but has also been used to describe older adults who lose weight, show loss of physical and/or cognitive function, and show signs of hopelessness and helplessness.
Eating and Feeding Problems
Undernutrition in older adults may reflect problems with eating and feeding. Treatment of eating and feeding problems varies, depending on the identified cause(s) and contributing factors.
Eating and swallowing
Swallowing is an important and complex task that can be affected by both normal aging and by diseases that are common in older persons. Swallowing can be divided into three stages on the basis of anatomy.
- The oral phase
Food is chewed and moved toward the back of the mouth (ie, the pharynx). This stage is under voluntary control.
- The pharyngeal phase
The swallow reflex begins, with food being moved past the larynx (ie, throat) into the esophagus. This stage is involuntary.
- The esophageal phase
Muscles in the esophagus move food down the esophagus. This stage is also involuntary.
Normal aging is associated with several changes in eating. With advanced age, we lose some of our taste sensation, and food can taste bland. We also lose some of our ability to smell, which further lessens taste sensation. Many older adults also complain of dry mouth, often as a side effect of medication. Problems with teeth or gums are common and reduce the ability to chew or forces chewing for a longer time before swallowing. Loss of muscle mass related to age (sarcopenia) in the jaws and throat may also contribute to difficulty in chewing or swallowing. In addition, diseases that produce swallowing difficulties (ie, dysphagia) are more common in older persons.
Dysphagia
Difficulty swallowing is called dysphagia. It can develop when a disease affects any part of the swallowing function. Dysphagia is usually classified as oral, pharyngeal, or esophageal, depending on which stage of swallowing is affected.
The most common cause of oral dysphagia is dementia. For example, scrambled eggs from breakfast may be discovered shortly before lunch in the cheeks of a person who has dementia. The most common cause of pharyngeal dysphagia is stroke, but other diseases may also cause pharyngeal dysphagia. These include diseases that affect the nervous system (eg, Parkinson's disease, brain tumor) or muscles in the throat (eg, myasthenia gravis, Lou Gehrig's disease), or other throat problems (eg, throat abscess or cancer). In pharyngeal dysphagia, food may get into the wind pipe, so that a person coughs, chokes, or blows food out of his or her nose while eating.
Several clinical tools are available to diagnose oral or pharyngeal dysphagia. The most common are the full bedside evaluation and the videofluoroscopic deglutition examination (VDE), which is a type of modified barium swallow. The VDE involves both x-ray and videotape evaluation of the person eating and swallowing. Treatment of both oral and pharyngeal dysphagia involves treatment of the underlying disease (when possible) along with an individualized feeding program. Such programs are designed by speech therapists who first identify what is not working for the person and then teach the person to do things to overcome the difficulty. Often, a dietician is also consulted to outline a modified diet that minimizes the difficulties.
A person with esophageal dysphagia feels a sensation of food getting "stuck" after a swallow. If neither solids nor liquids can be swallowed, there may be a problem with the motility, or muscle contractions, of the esophagus. If only solids are difficult to swallow, then there may be some kind of obstruction (eg, ulcers, tumor, or scarring of the esophagus). Esophageal dysphagia can also be caused by irritation of the esophagus caused by medication. Common drugs that can irritate the esophagus include potassium supplements, nonsteroidal anti-inflammatory agents (eg, aspirin and ibuprofen), alendronate, and tetracycline antibiotics. People with either scarring or motility problems benefit greatly from esophageal dilation.
Aspiration
If food accidentally goes down the wind pipe instead of the esophagus, the result is called aspiration. If aspirated material reaches the lungs, it can cause aspiration pneumonia. An especially serious problem can develop if stomach contents are aspirated into the lungs, eg, when an unconscious person chokes on his or her vomit. The stomach contains many irritating chemicals (eg, acid, enzymes) that can severely damage the lungs. People with known or suspected aspiration should undergo a swallowing study and work with a speech therapist to reduce their risk of ongoing problems.
Treatment
Treatment of eating and feeding problems depends on the underlying cause. Common causes include depression, very restrictive diets that ignore individual food preferences, social isolation, teeth or mouth problems, functional problems (eg, arthritis that prevents hand control), and reactions to medications that may cause loss of appetite, dry mouth, cognitive loss, or movement disorders. Dysphagia can also be caused by a variety of illnesses, including cancer and several nervous system or muscle disorders.
Until the underlying cause of an eating disorder is corrected, careful feeding by hand or tube feeding can be done. Speech therapists and dieticians specialize in feeding techniques and designing proper tube feeding regimens. Feeding by hand requires much patience and is labor intensive, while tube feeding is invasive and associated with its own risks. Intravenous feeding is sometimes also used.
Tube Feeding
There are several different approaches to tube feeding. When only short-term feeding is required, tubes can be placed into the stomach through the nose. For long-term support, tubes can be placed directly into the stomach or small intestine through an incision in the upper abdomen (eg, gastrostomy tubes). These can usually be placed without the use of general anesthesia.
Tube feeding requires a special level of care and may require institutionalization, although many people and their families learn to manage these devices at home. Complications of feeding tubes are numerous and include an increased risk of aspiration pneumonia (most serious), metabolic disturbances, diarrhea, and local tissue inflammation. An individual's risk of complications depends on his or her overall health. A person in the advanced stages of dementia who has trouble speaking and walking as well as eating is at high risk of complications and will likely not live better or longer when tube fed. On the other hand, a person in generally good health who has primarily a swallowing problem (eg, after a stroke or temporary illness that caused weight loss) will often benefit and may recover to swallow again when their nutrition is improved through the use of tube feeding.
IV feeding
Intravenous (IV) feeding is considered only when the gastrointestinal tract cannot be used for a long time, such as during treatment of bowel obstruction, severe gastrointestinal hemorrhage, intractable vomiting, or severe colitis. Feeding solutions include sugars, amino acids, emulsified fats, vitamins, minerals, and electrolytes. Older adults appear to tolerate this type of feeding well but need to be watched carefully for fluid retention. Complications associated with IV nutrition include those related to catheter insertion, deep-vein thrombosis, and infection.
Preventing Undernutrition
Preventing undernutrition is much easier than treating it. However, identifying and correcting deficiencies in frail individuals requires vigilant attention to nutrition and water intake. Often, food intake can be increased by making eating and meal times easier and more enjoyable. Some ways to do this include the following:
- Catering to food preferences as much as possible
- Avoiding restricted diets unless absolutely necessary
- Eating meals with a friend
- Providing enough time for a leisurely, relaxed meal
- Preparing foods of appropriate consistency, color, texture, temperature, and presentation
- Using herbs, spices, and hot foods to compensate for the loss of the taste of smell sensations and also to avoid using too much salt and sugar
- Avoiding packaging that is hard to open
- Making sure that seating is comfortable and at the proper height
Removing any obstacles or barriers to proper nutrition is essential. This includes correcting any underlying disease or condition, including mouth or hand problems that might interfere with eating or swallowing. Those needing assistance with eating should be helped. Specialized utensils are available for those with hand weakness or severe arthritis (see Rehabilitation). It is also important to correct underlying transportation or economic considerations that might limit obtaining food.
Title III C of the Older Americans Act provides for group and home-delivered meals for older adults, regardless of economic resources. This service is available in most parts of the country, although in some locations there is a waiting list. For information on obtaining meals, contact your area agency on aging (see Related Websites) or hospital social services department.
Supplements
Dietary supplements in the form of bars, wafers, and drinks are also available to improve nutrient intake. These should be used in addition to, and not as a substitute for, meals. They are best used in between meals and as an evening snack. Intake of other foods may decrease when such supplements are used, but overall nutrition may be increased because of the nutrient quality and density of the supplements.
Many vitamin and mineral supplements are commonly available in supermarkets and drugstores. Recommendations for older adults include higher intake of calcium (1200-1500 mg) and vitamin D (800 IU) to prevent osteoporosis. Some research suggests that folic acid, B6, and B12 may be helpful in reducing the risk of coronary artery disease and in preventing loss of cognitive function. Other research suggests that immune function may be improved by supplementation with protein, vitamin E, zinc, and other micronutrients. Still other studies suggest that antioxidant vitamins (eg, vitamins A, C, and E) may help in preventing age-related cataracts, macular degeneration, deaths from heart disease, and the progression of Alzheimer's disease. However, it is important to remember that many health claims are not yet proved and that dietary supplements should not be seen as a replacement for regular meals and proper nutrition. In addition, consumers are often unaware of potential risks, side effects, and drug interactions associated with many over-the-counter supplements. Older adults (or their caregivers) should discuss all supplements being taken with their healthcare providers, so that the appropriateness and safety of each supplement can be evaluated (see also Complementary and Alternative Medicine).
Ethical and Legal Issues
The Omnibus Budget Reconciliation Act of 1987 defines unacceptable weight loss in a nursing home setting as any weight loss =5% of total body weight in the past month or 10% in the past 6 months. Standards of care under Medicare dictate the following:
- That a nursing home resident maintains acceptable parameters of nutritional status, such as body weight and protein levels, unless the resident's clinical condition demonstrates that this is not possible
- That a resident receive a therapeutic diet when there is a problem. Adequate nutrition and hydration should always be provided unless
- a fully competent older person refuses invasive nutritional support after having been fully informed of the potential consequences and states this in written form with witnesses, or
- a terminally ill older person has executed a legally binding living will or medical directive that precludes artificial feeding in the case of terminal illness or impending death.
Standards of care and ethical principles also maintain that artificial feeding may be withheld or terminated according to a patient's advance directive after careful consideration of the overall prognosis. The patient and surrogate must be appropriately counseled regarding the consequences of withholding feeding. After nutrition is completely stopped, several weeks may ensue before death. In this setting, Palliative Care, including emotional support, is extremely important and complex.
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