Geriatric nutrition: Nutritional issues in older adults

INTRODUCTION — 

Changes associated with normal aging increase nutritional risk for older adults. Aging is characterized by diminished organ system reserves and weakened homeostatic controls.

Nutritional needs of older adults are determined by multiple factors, including specific health problems and related organ system compromise; an individual's level of activity, energy expenditure, and caloric requirements; the ability to access, prepare, ingest, and digest food; and personal food preferences.

This topic will discuss assessment of nutrition in the older adult, as well as the etiology, evaluation, and treatment of weight loss, overnutrition, and specific common nutrient deficiencies. Related issues of geriatric health maintenance and nutritional assessment are discussed separately. (See "Geriatric health maintenance" and "Approach to the patient with unintentional weight loss" and "Dietary assessment in adults" and "Vitamin intake and disease prevention".)

TERMINOLOGY — 

Although often used interchangeably, malnutrition and undernutrition are not synonymous. Malnutrition refers to a broader concept that, according to the World Health Organization, encompasses undernutrition as well as overweight conditions and obesity [1]. However, in this topic, malnutrition will be used synonymously with undernutrition.

HEALTHY DIET — 

A healthy diet for older adults should include a variety of foods that meet the recommended dietary allowances for nutrients and is similar to a healthy diet for younger adults (see "Healthy diet in adults"). Resources for older adults include MyPlate for Older Adults, a modified food guide pyramid based on the 2010 United States Department of Agriculture (USDA) food guidelines. The updated 2020 to 2025 USDA guidelines also have a recommended dietary section for older adults [2].

MALNUTRITION

Definitions for malnutrition vary. These definitions have proven to predict health-related outcomes, and are very useful for determining risk for complications, mortality, and incapacity. However, there is no schema that has proven to predict response to nutritional interventions when applied to the older individual.

Diagnostic criteria — Diagnostic criteria were introduced in 2018 by the Global Leadership Initiative on Malnutrition (GLIM). The GLIM was established in order to develop a global consensus on the identification and diagnostic criteria for malnutrition to facilitate the comparison of malnutrition prevalence, treatment, and outcomes [3]. The criteria include an appreciation of the role of acute and chronic inflammation. According to a 2024 report from the European Society for Clinical Nutrition and Metabolism, the GLIM criteria for 2018 remain useful criteria for malnutrition and have good predictive validity [4].

The GLIM criteria are the following:

The diagnosis requires the combination of at least one phenotype and one etiologic criteria:

●Phenotype criteria – Nonvolitional weight loss (>5 percent within the past six months or >10 percent beyond six months), low body mass index (BMI; <20 if <70 years old or <22 if >70 years old), or reduced muscle mass.

●Etiologic criteria – Reduced food intake (<50 percent of energy requirements for >1 week or any reduction for >2 weeks, or any chronic gastrointestinal condition that adversely impacts food assimilation) or absorption, or underlying inflammation due to acute disease/injury or chronic disease.

Prevalence and consequences — The prevalence of malnutrition in older adults is dependent upon the diagnostic criteria applied and the population studied, varying by geography, age distribution, and living situation.

●A review of studies using the Mini Nutritional Assessment (MNA) across settings and countries in Europe, the United States, and South Africa found the prevalence of malnutrition among 4507 older adults (mean age 82.3 years old, 75.2 percent female) was 22.8 percent [5]. Highest rates were in the rehabilitation setting (50.5 percent) and lowest among community dwellers (5.8 percent). Over one-third of hospitalized older adults (38.7 percent) in this study met the criteria for malnutrition.

●In a 2016 meta-analysis on malnutrition in older adults in various health care settings (mostly in Europe), including data from 240 studies and over 110,000 persons, rates of malnutrition were: outpatient 6 percent (95% CI 4.6-7.5), hospital 22 percent (95% CI 18.9-22.5), nursing homes 17.5 percent (95% CI 14.3-20.6), long-term care 28.7 percent (95% CI 21.4-36.0), and rehabilitation/subacute care 29.4 percent (95% CI 21.7-36.9) [6].

●Data from studies of acute hospitalization in older patients suggest that up to 71 percent are at nutritional risk or are malnourished [7].

Compared with younger adults, undernutrition in older individuals is both more common and may have greater impact on outcomes, including physical function [8], health care utilization [9], and length of stay for surgical hospitalizations [10,11].

Older adults are at risk of inadequate energy intake during hospitalization [12], and may be less able to adapt after periods of inadequate intake [13]. The lack of ability to compensate for periods of low food intake due to illness or other difficulties can result in long-term, persistent weight changes, especially when combined with social, medical, or psychological factors that can negatively impact body weight.

Studies suggest that weight loss in older adults, especially if it is not volitional, is predictive of mortality [14-16]. Loss of as little as 5 percent of weight over a three-year period is associated with increased mortality among community-dwelling older adults [17]. Weight loss for those with a BMI below 30 likely poses a greater mortality threat to older adults than not losing weight or of having a BMI of 25 to 30 [18].

Causes of weight loss

Inadequate dietary intake

Social factors — Social factors contributing to weight loss include:

●Increased likelihood of isolation at mealtimes – One-third of persons over 65 years old and one-half over 85 years old live alone, which typically decreases food enjoyment and calorie intake. Several studies have demonstrated that older adults who eat in the presence of others consume more than those who eat alone [19,20].

●Financial limitations affecting food acquisition – A greater proportion of older adults live near the poverty line, compared with the general population. Individuals with fixed incomes may use money previously spent on food for medications and other needed items.

Medical factors

●Malignancy – Malignancy is a frequently identifiable cause of undernutrition [21,22]. It may be due to cancer (especially of the gastrointestinal tract) or be related to cachexia [23]. (See 'Cachexia' below.)

●Depression – Depression and dysphoria are common in older adults and are important causes of weight loss [21]. (See "Diagnosis and management of late-life depression".)

●Dysphagia – Dysphagia is present in approximately 7 to 10 percent of the older adult population and has a negative effect on energy intake [24,25]. Dysphagia occurs commonly in patients with acute stroke [26] or Parkinson disease [27], as well as other etiologies. This is discussed separately. (See "Approach to the evaluation of dysphagia in adults".)

●Other medical etiologies – Nearly every acute or chronic disease can impact appetite or gastrointestinal function and limit intake.

●Feeding difficulties – Difficulty with feeding due to paralysis from stroke, severe arthritis, hand tremors, or dementia can limit intake.

●Oral concerns – Chewing difficulty, dental issues, and oral pain puts older adults at risk for poor intake [28,29].

Physiologic factors — Physiologic factors associated with weight loss include age-related decrease in taste and smell sensitivity, delayed gastric emptying, early satiety, and impairment in the regulation of food intake.

●Age raises the threshold for odor detection and lowers perceived odor intensity [30]. The number of taste buds remains constant, but thresholds for recognition of salt and other specific tastes increase. Impaired taste and smell likely alter the cephalic phase of digestion, affecting learned associations between the taste and smell of food with signals involved in meal initiation, volume of food intake, and meal termination.

●Decrease in the rate of gastric emptying in older adults may result in prolonged antral distension with reduced hunger and increased satiety [31].

●Aging may influence production of, and/or central nervous system sensitivity to, several digestive hormones thought to be involved in satiety. Glucagon, glucagon-like peptide 1, cholecystokinin, leptin, and ghrelin are peripheral satiety signals and appear to be less well-detected by the brain with increased age [32].

●Causes of impaired regulation of food intake include decreased stimulatory effects of neurotransmitters involved in appetite (eg, opioids, neuropeptide Y, the orexins and ghrelin) and increased sensitivity to the inhibitory effects of corticotropin-releasing factor, serotonin, and cholecystokinin.

Anorexia — Anorexia, a decrease in appetite, is influenced in older adults by multiple physiologic changes, and food intake has been observed to gradually diminishes with age [33]. Much of the intake reduction in early old age is likely an appropriate response to decreased energy needs due to reduced physical activity, decreased resting energy expenditure (REE), and/or loss of lean body mass.

Changes in taste and smell lead to a decreased desire to eat and early satiety develops with age, related to gastrointestinal changes and gastric hormone changes, as discussed above. (See 'Physiologic factors' above.)

Appetite regulation is further affected by illness, drugs, dementia, and mood disorders [34].

Cachexia — Cachexia has been defined as a "complex metabolic syndrome associated with underlying illness, and characterized by loss of muscle with or without loss of fat mass" [35]. It is associated with increased morbidity. Anorexia, inflammation, insulin resistance, and increased muscle protein breakdown are frequently associated with cachexia.

Cachexia impacts intake and gastrointestinal function, so poor nourishment is more common in patients with cachexia. However, cachexia is distinct from starvation, age-related loss of muscle mass (see 'Sarcopenia' below), or psychiatric, intestinal, or endocrinologic causes of weight loss. Cachexia involves many dysregulated pathways, leading to an imbalance between catabolism and anabolism.

Cachexia usually occurs in the setting of underlying illness involving a cytokine-mediated response. Examples of such illnesses include cancer, end-stage kidney disease, chronic pulmonary disease, heart failure, rheumatoid arthritis, and acquired immunodeficiency syndrome (AIDS). The pathogenesis, clinical features, and treatment of cancer-related cachexia are discussed separately. (See "Pathogenesis, clinical features, and assessment of cancer cachexia" and "Management of cancer anorexia/cachexia".)

Sarcopenia — Sarcopenia is a syndrome characterized by the loss of muscle mass, strength, and performance [36-39]. Low muscle mass is defined as a decrease in appendicular muscle mass two standard deviations below the mean for young healthy adults [40], and is usually measured by dual-energy X-ray absorptiometry or bioelectrical impedance in clinical practice. Unlike cachexia, sarcopenia does not require the presence of an underlying illness. Also, whereas most people with cachexia are sarcopenic, most sarcopenic individuals are not considered cachectic [41]. Sarcopenia is associated with increased rates of functional impairment, disability, falls, and mortality [42]. Loss of muscle mass, accompanied by decreased muscle strength, can occur in overweight individuals (sarcopenic-obese), as well as in normal and underweight individuals.

Causes of sarcopenia may include endocrine changes, activation of proinflammatory cytokines, reduced alpha motor units in the spinal cord, decreased physical activity, and suboptimal protein intake.

●Reductions in testosterone and estrogen that accompany aging appear to accelerate the development of sarcopenia [43]. Relative deficiencies of estrogen and testosterone contribute to muscle catabolism and promotion of catabolic cytokines such as interleukin (IL)-1 and IL-6 [13]. Furthermore, testosterone inhibits myostatin, stimulates myoblast, and increases satellite cells within muscle. Testosterone replacement may increase muscle mass, but studies have not demonstrated similar benefit for estrogen replacement [44-46]. Selective androgen receptor modulators such as enobosarm are a promising potential treatment for sarcopenia. A phase II trial of enobosarm in healthy older adults led to increases in lean body mass and improvement in stair climbing [47]. While an increase in muscle mass is of interest, it is the functional and health benefits that are most important.

●Insulin resistance increases with age. Insulin inhibits muscle breakdown and the reduction of insulin action on muscle may contribute to muscle catabolism [48].

●Inadequate protein intake can also contribute to sarcopenia and decreased function. A prospective cohort study found that adults aged 70 to 79 with protein intake ≤0.8 g/kg/day (the recommended dietary allowance) were at greater risk of developing mobility limitations over six years of follow-up than those with protein intake ≥1 g/kg/day [49]. Randomized trials are required to confirm whether this is causal or coincidental.

Strength training for older adults, including those with sarcopenia, is discussed separately. (See "Practical guidelines for implementing a strength training program for adults", section on 'Important considerations for strength training in older adult patients' and "Strength training for health in adults: Terminology, principles, benefits, and risks", section on 'Sarcopenia'.)

SCREENING FOR NUTRITIONAL STATUS — 

Elements of screening include measuring weight, calculating weight loss, and utilizing screening tools.

Nutritional screening for older adults is discussed separately. (See "Geriatric health maintenance", section on 'Nutrition'.)

Screening tools — Screening tools have been developed to identify older adults at risk for poor nutrition.

The two screening tools in the highest quartile for sensitivity (>83 percent) and specificity (>90 percent) are the Malnutrition Screening Tool (MST) and the Mini Nutritional Assessment (MNA)-Short Form (MNA-SF) [50]. The MNA is used most often by nutritionists.

●The MST was developed for use in acutely hospitalized patients and also validated for use in cancer patients (average age 57 to 60 years old, range 15 to 89 years old) [51]. It asks two simple questions: "Have you been eating poorly because of a decreased appetite?" and "Have you lost weight recently without trying?" The sensitivity of the MST in hospitalized patients ranges from 74 to 100 percent with a specificity of 76 to 93 percent when compared with the Subjective Global Assessment (SGA).

●The MNA consists of a global assessment and subjective perception of health, as well as questions specific to diet, and a series of body measurements [52]. It has been widely validated and is predictive of poor outcomes [53-55]. The shorter MNA-SF uses six questions from the full MNA and can substitute calf circumference if body mass index (BMI) is not available. A validation study demonstrated good sensitivity compared with the full MNA [56].

EVALUATION OF WEIGHT LOSS

Initial evaluation — Recommendations vary on the degree of weight loss, and the period of time for weight loss, that should prompt clinical investigation. One commonly accepted but arbitrary definition for clinically important weight loss is loss of 4 to 5 percent of total body weight over 6 to 12 months [14]. Unintentional weight loss should lead to clinical concern regardless of whether the patient is overweight at baseline.

Document weight loss — Serial measurements of body weight offer the simplest evaluation of nutritional adequacy and change in nutritional status in older adults. Obtaining periodic body weights may be challenging, particularly in frail patients. A chair or bed scale that is regularly calibrated may be needed for patients who cannot stand on an upright balance beam scale. Historical information from the patient and/or family may provide clues to weight loss (change in clothing size, appearance) even if actual measurements are not available. Assessment of muscle mass may also be of clinical utility. Methods for determining body composition are discussed separately. (See "Determining body composition in adults".)

Evaluate nutritional intake — Evaluate appetite and dietary intake. Determining if there has been a change in hunger and satiety may provide more clinically revealing information than performing a formal dietary recall. Patients should be questioned regarding appetite, their dietary intake in relation to their usual pattern, the number of meals they consume per day, portion size, snacks between meals, if and when they feel full during their meal, and whether the patient likes what they are eating. The Subjective Global Assessment (SGA), Mini Nutritional Assessment (MNA), and Simplified Nutritional Appetite Questionnaire are all tools that include evaluation of aspects of dietary intake. A consultation with a nutrition professional (eg, registered dietitian) is optimal.

Basic workup — Perform a complete history, including oral symptoms, and physical examination, including a complete oral examination. As a baseline, we suggest laboratory evaluation for evidence of metabolic or inflammatory disease, to include a basic chemistry profile including glucose and electrolytes, thyroid-stimulating hormone, complete blood count, and also C-reactive protein and albumin if inflammation/cachexia is suspected. Chest and plain abdomen radiographs may be considered. Although studies describing the causes of involuntary weight loss have routinely performed chest radiographs and abdominal films, there is no clear evidence of their value. Order additional studies based on suspicion of underlying disease from the patient's history and examination, if this is aligned with goals of care.

Subsequent evaluation — The subsequent evaluation of patients with weight loss is discussed separately. (See "Approach to the patient with unintentional weight loss".) (algorithm 1)

TREATMENT OF WEIGHT LOSS

Treat underlying conditions — When an underlying cause of weight loss is identified, such as depression, a medical illness, the inability to chew or swallow food, or medication side effects, it is obviously important to treat the condition. In addition, nutritional repletion should be provided to restore the patient to a target weight, with recognition that weight correction in the older population is less readily accomplished than in younger people, especially in the presence of inflammation/cachexia.

The Council for Nutritional Clinical Strategies in Long-Term Care has developed an evidence-based approach to nutritional surveillance and management for patients in long-term care [57]. Treatment recommendations are based on common reversible causes of malnutrition, as described by the mnemonic "MEALS ON WHEELS" (table 1). Likewise, the American Academy of Home Care Physicians has developed guidelines for unintended weight loss in home care patients [58].

Engage a nutritionist — Patients who have significant involuntary weight loss benefit from referral to a dietitian. Recent studies have shown that individualized dietary counseling and plans are more effective in regaining weight than ordering oral nutritional supplements alone [4,59]. Nutritionists can provide individualized recommendations for weight gain.

Calorie and protein requirements — The ability to estimate older adults' caloric needs will enable clinicians and nutritionists to avoid undernutrition or overnutrition. Indirect calorimetry is the gold standard in obtaining resting energy expenditure (REE), but it is not practical in clinical settings. The Harris-Benedict equation has been used to predict REE for over a century, but its accuracy is approximately 75 percent. For older patients with chronic disease, hospitalization, or overweight, the Harris-Benedict equation is less accurate. Although other equations have been developed, none are better than the Harris-Benedict equation in predicting REE in healthy older adults [60-62].

Harris-Benedict equation:

Men: REE = 66.473 + 13.7516 (weight in kg) + 5.0033 (height in cm) – 6.7550 (age)

Women: REE = 655.0955 + 9.5634 (weight in kg) + 1.8496 (height in cm) – 4.6756 (age)

The European Society for Clinical Nutrition and Metabolism practical guidelines recommended at least 1 g protein per kg body weight for older adults, although studies have recommended higher intakes of protein for older adults at 1 to 1.2 g/kg/day to prevent lean muscle mass loss [63]. During stress or injury, protein requirement may increase to 1.5 g/kg/day, but these requirements need to be adjusted for patients with renal or hepatic insufficiency.

Address inadequate food intake — If the patient's food intake is inadequate:

●Dietary restrictions – Lift dietary restrictions whenever possible. In one study, undernutrition (average weight loss >1 lb per month, serum albumin <3.5 g/dL) was associated with dietary restrictions [64]. Fifty-nine percent of the patients with weight loss and 75.2 percent of those with hypoalbuminemia were on some type of dietary restriction.

In older adults with high nutritional risk and diabetes, regular monitoring of blood glucose and adjustment of medication is preferable to dietary restriction or even a "no concentrated sweets" prescription. The short-term substitution of a regular diet for a diabetic diet increased calorie consumption and did not cause gross deterioration of glycemic control in a study of chronic care patients with type 2 diabetes [65].

●Assistance with feeding or shopping – Ensure that feeding or shopping assistance is available, if appropriate. In a crossover controlled trial of feeding assistance in nursing home residents at risk of weight loss, those in the intervention group showed a significant increase in daily caloric intake and either maintained or gained weight, whereas those in the control group lost weight. Feeding assistance was resource-intensive and required an average 37 more minutes of staff time per meal [66]. Social work support may be important if inadequate finances are contributing to poor intake.

●Food preferences – Assure that meals and foods meet individual tastes. Suggest offering foods that fit the patient's ethnic or regional preferences.

●Dietary supplementation

•Consider ways to supplement the patient's diet. Increase the nutrient density of food. For example, increase protein content by adding milk powder, whey protein (found in many health food stores), egg whites, or tofu. Increase fat content by adding olive oil (or other "good fat") in preparation of sauces, fresh or cooked vegetables, and grains or pasta. If weight does not improve, offer daytime snacks between meals.

•Give a daily multivitamin and mineral supplement until the cause of inadequate intake is determined.

•Consider a liquid dietary supplement. (See 'Nutritional supplements' below.)

Nutritional supplements — Commercial oral nutritional supplements are commonly offered to older adults, especially in long-term care settings; however, evidence of their benefit is limited and we do not routinely use them [67-69].

In a meta-analysis evaluated 55 trials of oral nutritional supplements to prevent malnutrition in older, high-risk patients (in hospital, community and long-term care settings), nutritional supplementation resulted in modest improvement in percentage weight change (weighted mean difference 1.75 percent, 95% CI 1.2-2.3), with slightly greater weight increase in patients at home or in long-term care [58]. A mortality benefit was found in hospitalized undernourished patients who were 75 years or older and who received supplements with higher calorie content. However, a systematic review of 244 trails among 28,619 hospitalized participants receiving several forms of nutrition support including oral, enteral and food fortification found no beneficial effect in terms of mortality or other adverse outcomes [70].

The limited benefit of supplements in patients with failure to thrive is discussed separately. (See "Failure to thrive in older adults: Management", section on 'Interventions of no or marginal benefit'.)

Limited role for appetite stimulants — There are few studies of these appetite stimulants in the older population with weight loss and failure to thrive. We do not routinely use them in our practice. The use of appetite stimulants in patients with cancer, or human immunodeficiency virus (HIV)/AIDS is discussed separately. (See "Management of cancer anorexia/cachexia", section on 'Pharmacologic treatments' and "Assessment and management of anorexia and cachexia in palliative care", section on 'HIV/AIDS'.)

●Megestrol acetate – Megestrol acetate, a progestational agent, has been shown to yield some weight gain and improved appetite in certain patient populations, which is discussed separately (see "Management of cancer anorexia/cachexia", section on 'Progesterone analogs'). However, there are significant adverse effects of megestrol acetate including edema, congestive heart failure, deep venous thrombosis, muscle weakness, and increased mortality [71-74]. The 2023 Updated Beers Criteria recommends avoiding megestrol acetate due to the unfavorable risk-to-benefit ratio [75]. The American Geriatrics Society "Choosing Wisely" campaign also recommends not using megestrol acetate due to lack of improvement in quality of life or survival and the increased risk of thrombotic events, fluid retention, and death [76].

●Dronabinol – Dronabinol has not been well studied in older adults [77,78], although one nonrandomized trial showed that dronabinol may be useful for anorexia, weight gain, and behavior problems in patients with advanced Alzheimer disease who were refusing food [77]. Dronabinol has significant central nervous system side effects, limiting its use for most older adult populations. The use of this agent in patients with cancer and anorexia/cachexia is discussed separately. (See "Management of cancer anorexia/cachexia", section on 'Cannabis and cannabinoids'.)

●Mirtazapine – Mirtazapine, an antidepressant that leads to more weight gain than selective serotonin reuptake inhibitor antidepressants, is commonly used for management of depression and weight loss in older adults. However, few studies have been specifically performed to evaluate its impact on weight among older adults with weight loss. Two studies in nursing home residents did not show conclusive benefit for mirtazapine over other nontricyclic antidepressants [79,80]. However, a retrospective study in patients with Alzheimer disease and weight loss found that patients treated with mirtazapine for three months had modest weight gain [81].

●Ghrelin mimetics – Ghrelin is an endogenous growth hormone secretagogues (GHS) that has been shown to stimulate appetite and increase fat-free mass. There are limited data to assess the benefit and safety of GHS in the treatment of older adults with sarcopenia, cachexia, or weight loss [82,83]. Adverse effects of ghrelin mimetics include hyperglycemia, dizziness, and nausea. The use of these agents in patients with cancer is discussed separately. (See "Management of cancer anorexia/cachexia", section on 'Growth hormone and ghrelin analogs (anamorelin)'.)

OVERNUTRITION — 

Adverse health effects due to overnutrition in the general adult population are discussed separately (see "Overweight and obesity in adults: Health consequences"). In older adults, a few studies suggest that being overweight as an older adult is associated with increased mortality:

●In a study of men 60 to 79 years in the United Kingdom, mortality was not increased for overweight or obese participants as defined by body mass index (BMI) [84]. However, mortality risk was increased with increasing waist circumference and with BMI, when data were corrected for differences in mid-arm muscle circumference. These findings suggest that cardiorespiratory fitness and muscle mass may play an important role in the relationship between BMI and mortality.

●Another report found a U-shaped pattern in women ≥65 years of age, comparing mortality across weight quintiles, with lower mortality for women in the middle three quintiles [85]. A J-shaped pattern for BMI and mortality was demonstrated in another study of adults, predominantly men, over age 60 years old [86]. In this study, BMI in the overweight range was protective.

Although the mortality risk of obesity may lessen with age, there are still metabolic and functional benefits to weight loss in obese older adults. Increasing obesity in older adults is associated with new or worsening disability [87], and weight loss can improve physical function, blood glucose and cholesterol levels, and quality of life [88,89]. The relative benefit of intentional weight loss in obese older adults with osteoarthritis, impaired activity tolerance, diabetes mellitus, and coronary artery disease, especially when combined with exercise, is becoming increasingly apparent [90-92].

Recommendations to lose weight should be individualized to the risk profile of particular patients. Those who are experiencing significant adverse effects associated with obesity (such as pain from osteoarthritis, obstructive sleep apnea, poor mobility, and falls) should be encouraged to pursue cautious weight loss. Few randomized controlled clinical trials have shown that diet and exercise combination can lead to successful weight loss and improve cardiometabolic risk factors and physical function for obesity older adults without adverse effects [92-94], but only in the context of regular exercise and appropriate calcium and vitamin D supplementation. Negative outcomes associated with weight loss in overweight older adults include loss of muscle mass and decrease in bone mineral density; both of these may be mitigated with regular exercise and vitamin D supplementation [95-100].

Sarcopenic obesity is a combination of age-related muscle atrophy and increase in adiposity, and this condition has been associated with increased mortality rate and greater risk for falls and cognitive impairment [101,102]. Several clinical trials of high-protein weight-loss diets have demonstrated success in weight loss while preserving lean mass and function [103,104]. Porter Starr et al randomized 67 obese older adults (BMI mean 36.9±6.3) to normal weight loss diet and high-protein weight-loss diet for six months. Both groups lost significant weight loss, but the high-protein diet group improved their Short Physical Performance Battery score compared with the control group [105].

MICRONUTRIENT DEFICIENCIES IN OLDER ADULTS — 

The following vitamins and mineral deficiencies are seen commonly in older patients, particularly those with malnutrition or involuntary weight loss.

Vitamin B12 deficiency — The prevalence of B12 deficiency in older adults ranges between 10 and 20 percent [106]. In the past, a majority of B12 deficiencies were thought to result from intrinsic factor deficiency; however, it is now known that approximately 15 percent of older adults (>60 years old) poorly absorb protein-bound B12 [107]. The diagnosis of B12 deficiency is discussed separately. (See "Clinical manifestations and diagnosis of vitamin B12 and folate deficiency".)

Patients with B12 deficiency can generally be treated with oral B12 [108]. (See "Treatment of vitamin B12 and folate deficiencies".)

Vitamin D deficiency — Many older adults have low levels of serum 25-hydroxyvitamin D (25[OH]D) levels (<20 ng/mL or 50 nmol/L). However, levels should be interpreted in context in patients with low serum protein levels, since vitamin D carrier protein also decreases in that setting. Older individuals at higher risk for vitamin D deficiency include those who are institutionalized, homebound, have limited sun exposure, obesity, dark skin, osteoporosis, or malabsorption. Monitoring of serum 25(OH)D levels is recommended for those at high risk, with the goal of achieving levels ≥30 ng/mL. Testing at three to four months following initiation of vitamin D supplements, if needed, should be done to assure that the target has been achieved. (See "Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment".)

A combination of exercise and vitamin D supplementation is associated with increase in muscle mass and improvement in function among older adults living in a community [109,110]. Therefore, increased consumption of dietary sources of vitamin D should be encouraged in all older adults. (See "Overview of vitamin D", section on 'Requirements'.)

Vitamin D supplementation is discussed separately. (See "Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment", section on 'Dosing'.)

Inadequate intake of calcium — Calcium nutrition is strongly influenced by age. The efficiency of calcium absorption from the gastrointestinal tract decreases significantly after age 60 years old. Individuals between 70 and 90 years of age absorb approximately one-third less calcium than do younger adults. Osteoporosis affects more than 10 million people in the United States and causes more than 1.5 million fractures within that population each year [111].

Given the impact of calcium deficiency on cortical bone loss, the adequate intake reference value for calcium for those >51 years of age was increased from 800 (1989 recommended dietary allowance) to 1200 mg/day. Food sources of calcium and available calcium supplements are shown in tables (table 2 and table 3). (See "Calcium and vitamin D supplementation in osteoporosis".)

Multivitamin supplementation — Many older adults use multivitamin supplements; however, available evidence fails to provide support or provides only weak evidence for benefit for this practice [112-117].

Routine supplementation with multivitamins and minerals is not likely to be beneficial unless it is clear that the older adult is not meeting their micronutrient needs due to low overall intake [118]. Multivitamins are discussed in detail elsewhere. (See "Vitamin intake and disease prevention", section on 'Multivitamins'.)

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Healthy diet in adults".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Malnutrition (The Basics)" and "Patient education: Malnutrition – Discharge instructions (The Basics)" and "Patient education: Vitamin B12 deficiency and folate deficiency (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Involuntary weight loss – We use involuntary loss of more than 5 to 10 percent of an older person's usual weight during one year as an important clinical sign of potential for increased risk for mortality. Weight loss should thus be met with concern and prompt a search for the cause. (See 'Malnutrition' above.)

●Causes of involuntary weight loss – Involuntary weight loss is generally related to one or a combination of four conditions: inadequate dietary intake, appetite loss (anorexia), muscle atrophy (sarcopenia), or inflammatory effects of disease (cachexia). (See 'Causes of weight loss' above.)

•Inadequate dietary intake may relate to social, psychological, medical, and physiologic issues. Depression is the most prevalent associated condition in several studies, with cancer as the second most common cause. (See 'Inadequate dietary intake' above.)

•Proinflammatory cytokines are common in older adults and are particularly elevated in patients with cachexia. Sarcopenia is often related to a reduction in testosterone and estrogen and increase in insulin resistance. (See 'Cachexia' above and 'Sarcopenia' above.)

●Evaluation – Evaluation of weight loss should include serial weight measurements, dietary or appetite assessment, history, physical examination, and screening laboratory studies. Additional studies should be based on findings of the initial evaluation and may include upper gastrointestinal endoscopy for patients with early satiety or thoracic/abdominal/pelvic computed tomography (CT) scan for patients with unexplained ongoing weight loss. (See 'Evaluation of weight loss' above.)

●Treatment – Treatment should be directed at the underlying cause (ie, depression) as well as dietary modification. Nutritional restrictions should be lifted; patients with diabetes may do well with a regular diet and adequate monitoring. High-calorie foods should be provided. (See 'Treatment of weight loss' above.)

We refer patients with significant weight loss who did not regain weight with adjustments in meal preparation to a nutritionist. Nutritionists can provide individualized dietary recommendations and outline plans to regain weight. (See 'Engage a nutritionist' above.)

●Overnutrition – Mortality risk in people over age 70 is not significantly impacted by an elevated body mass index (BMI) in the 25 to 29.9 range. Advice regarding weight loss for the overweight older person should be tailored to the individual, assessing the impact of excess weight on their quality of life, and should include the need for regular exercise. (See 'Overnutrition' above.)

●Micronutrient deficiencies – Older adults are at risk of nutrient deficiencies, although evaluation and treatment are the same as for younger patients.

•Vitamin B12 deficiency – Vitamin B12 deficiency affects approximately 15 percent of people >60 years old in the United States and most commonly relates to malabsorption of food-protein-B12 complexes. Patients with B12 deficiency can generally be treated with oral B12 [108]. (See "Treatment of vitamin B12 and folate deficiencies".)

•Vitamin D and calcium deficiency – Vitamin D deficiency is also common in older adults. Screening for vitamin D deficiency and vitamin D supplementation is discussed separately. (See 'Vitamin D deficiency' above and "Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment", section on 'Dosing'.)