The European Society for Clinical Nutrition and Metabolism (ESPEN) defines malnutrition in older adults not primarily by body weight, but by several dimensions simultaneously. The GLIM criteria (Global Leadership Initiative on Malnutrition, 2019) require at least one phenotypic and one etiological criterion for diagnosis:
- Phenotypic: Unintentional weight loss of more than 5 percent over three months or more than 10 percent over six months, low BMI (below 20 in older adults), or documented loss of muscle mass.
- Etiological: Reduced food intake or increased energy requirements due to illness and inflammation.
It is important to understand this finding: A 75-year-old woman who is malnourished may have significant protein deficiencies and muscle loss even if she is of normal weight. The classic view that “thin is good, fat is bad” leads to systematic misinterpretations in older adults.
- Older adults living at home: 5 to 10 percent are malnourished; 25 percent are in the at-risk category.
- Hospitals: 25 to 30 percent of geriatric patients are malnourished upon admission—many of whom become even more malnourished during their stay.
- Nursing homes: 30 to 40 percent of residents.
- After surgery: In the first few weeks following surgery, up to 60 percent of older patients have a nutritional deficit—particularly relevant in the context of surgical risk in older adults.
- Dialysis patients and cancer patients: These groups are among the highest-risk, often with a prevalence exceeding 50 percent.
The reasons are varied and often cumulative:
Physical factors
- A decline in the sense of smell and taste makes food less appealing
- Dental problems, ill-fitting dentures, and difficulty swallowing
- Slower gastric emptying and an earlier feeling of fullness
- Reduced ability to sense hunger and thirst
- Chronic pain that reduces appetite and the desire to cook
- Conditions requiring increased energy intake (COPD, heart failure in older adults, tumors)
Medication-related causes
- Many medications alter taste or appetite—a key issue in polypharmacy among the elderly
- Anticholinergic medications cause dry mouth
- Proton pump inhibitors interfere with vitamin B12 absorption
- Metformin can cause vitamin B12 deficiency
- Certain antidepressants reduce appetite
Psychological and social factors
- Depression in older adults—one of the strongest single factors contributing to malnutrition
- Loneliness — people who eat alone eat less
- Cognitive impairment to dementia in older adults—meals are forgotten or no longer recognized
- Poverty—healthy foods can become too expensive
- Limited mobility — shopping and cooking become more difficult. More on this: Immobility in old age
- Grief, loss, moving
Medical and nursing care reasons
- Systematic underestimation of protein requirements in older adults
- Hospital food designed for younger patients
- Fasting periods before medical tests that are not made up for
- Failure to adapt to swallowing difficulties
→ How polypharmacy in older adults can affect appetite and nutrient intake.
→ The role of depression in older adults as a barrier to nutrition.
The evidence is clear. Malnutrition in older adults increases:
- Mortality: A doubling of 1-year mortality in the hospital and thereafter.
- Risk of infection: Pneumonia in older adults, wound infections, urinary tract infections.
- Wound-healing disorders: Delayed healing, increased risk of pressure ulcers.
- Postoperative complications: A significantly increased rate of complications across all surgical disciplines.
- Length of hospital stay: On average, 3 to 7 days longer.
- Sarcopenia and frailty: The direct biological link—without sufficient protein, there is no muscle; without muscle, there is no function. More on this: Sarcopenia in older adults and frailty syndrome.
- Hospital readmissions: Significantly increased in the three months following discharge.
- Nursing home admissions: Increased risk of losing independence.
- Total costs: Malnutrition significantly increases healthcare costs per patient.
→ On the closely related issue of muscle loss: Sarcopenia in older adults.
→ On the overarching issue of frailty syndrome.
A structured nutritional assessment is not optional but mandatory—especially before planned surgeries, upon hospital admission, and in primary care for patients with multiple chronic conditions. Frailty screening routinely includes a nutritional assessment.
Screening Tests
- Mini Nutritional Assessment (MNA): The standard in geriatric medicine. Assesses weight trends, appetite, BMI, calf circumference, and mobility. A screening score below 12 requires the long-form assessment; a score below 17 indicates overt malnutrition.
- Nutritional Risk Screening (NRS-2002): Widely used in hospitals. Assesses disease severity and nutritional status.
- MUST (Malnutrition Universal Screening Tool): Particularly useful in outpatient settings.
Confirmation of diagnosis according to GLIM criteria
Confirmation through a combination of phenotypic and etiological criteria. Inclusion of body composition (BIA, DXA) for more detailed assessment.
Identification of Causes
- Detailed dietary history over several days
- Oral cavity and dental status; swallowing assessment if suspected
- Laboratory: total protein, albumin, CRP, transferrin, vitamin B12, folic acid, vitamin D, iron, ferritin, zinc, TSH
- Medication review for appetite-suppressing or malabsorptive agents — structured according to deprescribing criteria
- Depression and cognitive screening
- If weight loss is unexplained, screen for tumors
???? The simplest clinical early warning sign: weight trend. If an elderly family member loses more than 5 percent of their body weight in three months—without consciously dieting—this is not “weight loss,” but a reason for medical evaluation. An unexplained weight loss of 5 kilograms in a 70-kg patient is the threshold.
1. Optimize protein intake
The key figure: 1.0 to 1.2 g of protein per kg of body weight per day for healthy older adults. In cases of illness, recovery from surgery, or malnutrition, 1.2 to 1.5 g per kg. For a 70-kg patient, that means 70 to 105 g daily.
It’s not just the total amount that matters, but also the distribution and quality:
- 25 to 30 g per main meal stimulate muscle synthesis
- Animal protein (fish, eggs, lean meat, dairy products) with a high leucine content is particularly effective
- Plant-based combinations (legumes plus grains) are good complementary sources
- Quark, cottage cheese, and yogurt products serve as simple sources of protein
2. Ensure adequate energy intake
In cases of malnutrition, protein alone is not enough—total caloric needs must be met. 30 to 35 kcal per kg of body weight per day is typical for older adults; more is needed in cases of illness. Those who consume too little energy overall burn the protein they consume for energy—and cannot build muscle.
3. Micronutrients
- Vitamin D: Common deficiency; supplementation is recommended when levels are confirmed to be below 50 nmol/l—particularly important for preventing osteoporosis in older adults.
- Vitamin B12: Especially important for those taking proton pump inhibitors or metformin.
- Folic acid: In specific cases.
- Iron: For anemia, but only when a deficiency is confirmed.
- Zinc: For impaired wound healing and recurrent infections.
- Fluids: Recommended intake of about 1.5 to 2 liters per day; more in hot weather or when taking diuretics. Dehydration is a distinct clinical category and is closely linked to malnutrition.
4. Liquid Nutrition
Oral Nutritional Supplements (ONS) are one of the best-evidenced interventions in geriatric medicine. They typically provide 250 to 400 kcal and 15 to 20 g of protein per serving. Studies show that in patients with malnutrition or at risk of malnutrition, oral nutritional supplements reduce mortality, complications, and readmissions to the hospital. They are prescribed by a doctor, who determines the individual dosage.
5. Treating the Causes
- Recognizing and treating depression in older adults—often the key factor
- Diagnosing and addressing swallowing disorders (texture modification, speech therapy)—often following early geriatric rehabilitation
- Dental treatment, denture adjustment
- Medication review to identify drugs that interfere with appetite or absorption—more on this: deprescribing
- Addressing social isolation — shared meals, meal delivery services, day care
- In cases of cognitive impairment: Structured meal assistance, clear presentation
- Weigh the person regularly: Once a month is sufficient. Record the weight. Trends are more meaningful than individual readings.
- Observe eating habits: How much is actually being eaten? Is food left on the plate?
- Notice changes in clothing: Pants getting looser, rings fitting more loosely—often visible sooner than numbers on the scale.
- Eat together: People who eat with others eat more. This isn’t just advice—it’s backed by data.
- Small portions, high-calorie density: Full-fat instead of reduced-fat, butter instead of nothing, cream in soups.
- Protein-rich snacks: quark, yogurt, cottage cheese, hard-boiled eggs.
- Don’t moralize about nutrition: Don’t pit “healthy” against “unhealthy.” For older adults, quantity and density come first, then composition.
Reasons for a structured nutritional assessment:
- Unintentional weight loss of more than 5 percent in three months or 10 percent in six months
- Persistent loss of appetite lasting several weeks
- Visible muscle loss, weakness, loss of strength—possible signs of sarcopenia
- Frequent infections, poor wound healing
- Before planned major surgeries—relevant to surgical risk in older adults
- After a hospital stay resulting in functional impairment
- In cases of swallowing difficulties or changes in eating habits
The first point of contact is the primary care physician, who will refer the patient to a nutritionist, speech-language pathologist, or geriatrician as needed. Specialized geriatric centers take an interdisciplinary approach, working with nutrition therapists who can explain the difference between advice from self-help guides and evidence-based, individually tailored nutritional therapy.
→ How a comprehensive geriatric assessment provides a structured evaluation of nutrition.
