Malnutrition in Older People

Introduction

Malnutrition is a state in which a deficiency of energy, protein or micronutrients causes measurable adverse effects on body composition, function and clinical outcome. It is common and frequently under-recognised in older people, affecting a substantial proportion of hospital inpatients and care home residents, and it independently worsens outcomes across almost every other condition - impaired wound healing, higher infection risk, reduced muscle strength and mobility, longer hospital stay, and increased mortality.¹

It matters as an exam topic because it is highly treatable when recognised early, and because the causes in older people are characteristically multifactorial - physical, psychological and social factors interact, and management that addresses only one domain often fails.

Several age-related changes make older people intrinsically more vulnerable. Appetite declines with age - sometimes called the 'anorexia of ageing' - through altered gut hormone responses, delayed gastric emptying producing earlier satiety, and blunted taste and smell that make food less appealing. Superimposed on this reduced baseline intake, any additional insult (an acute illness, a bereavement, a new medication causing nausea, or the loss of a partner who did the cooking) can tip a precarious balance into overt malnutrition surprisingly quickly.

Screening: MUST

The Malnutrition Universal Screening Tool (MUST) is the standard validated UK tool, quick to perform and used across hospital, community and care home settings.²

Causes of malnutrition in older people

Malnutrition in older people is rarely due to a single cause. A useful approach is to consider physical, psychological, social and disease-related contributors together, since several often coexist in the same patient.

Assessment

• Weight history, including rate and pattern of any loss, and clothing/dentures fitting more loosely
• Dietary history: what a typical day's intake looks like, appetite, and any difficulty chewing or swallowing
• Functional ability to shop, cook and eat independently
• Social circumstances: who they live with, financial constraints, and social support at mealtimes
• Mood screening, given the strong overlap with depression
• Cognitive screening where dementia is a plausible contributor
• Medication review for drugs causing dry mouth, nausea, altered taste, or early satiety
• Examination for signs of specific deficiency (e.g. glossitis, angular stomatitis, peripheral oedema from hypoalbuminaemia) and for muscle wasting

Management: a stepped approach

Food-first approach

Fortifying and optimising normal food intake is first-line, before reaching for prescribed oral nutritional supplements, and is often sufficient on its own.

• Fortifying meals with full-fat milk, cream, butter, cheese or oil to increase energy density without increasing meal volume
• Small, frequent, nutrient-dense meals and snacks rather than three large meals, particularly where appetite is limited
• Addressing practical barriers: assistance with shopping and cooking, meal delivery services, eating with company where isolation is a factor
• Optimising the eating environment: appropriate positioning, adequate time, assistance with feeding where needed, and treating pain or nausea that limits intake
• Addressing oral health: dental review, well-fitting dentures

Oral nutritional supplements

Prescribed sip feeds are used where food fortification alone is insufficient, generally guided by dietitian input, and reviewed regularly rather than continued indefinitely without reassessment.

Enteral and parenteral nutrition

Considered where oral intake is inadequate or unsafe (e.g. significant dysphagia) despite the above measures, and where the patient's overall prognosis and wishes support artificial nutritional support.

• Nasogastric feeding: short- to medium-term, for example after an acute stroke with dysphagia expected to improve
• Percutaneous endoscopic gastrostomy (PEG): for longer-term enteral feeding where the gut is functioning but oral intake remains unsafe or inadequate long-term
• Parenteral nutrition: reserved for patients with a non-functioning or inaccessible gastrointestinal tract, given its higher complication rate (line infection, metabolic complications)

Refeeding syndrome

Refeeding syndrome is a potentially life-threatening shift in fluid and electrolytes that can occur when nutrition (particularly carbohydrate) is reintroduced too rapidly after a period of prolonged inadequate intake, driven by a sudden insulin-mediated shift of phosphate, potassium and magnesium into cells.

Specific micronutrient deficiencies

Malnutrition in older people is usually a combined energy-protein deficit, but specific micronutrient deficiencies occur alongside it and some produce distinctive clinical syndromes worth recognising.

Malnutrition and sarcopenia

Malnutrition and sarcopenia are closely linked and often coexist - inadequate protein intake accelerates muscle loss, and the resulting weakness can itself worsen appetite and the ability to shop and cook, creating a self-reinforcing cycle. Nutritional management should therefore be paired with resistance exercise where feasible, as described in ³, rather than treated as an entirely separate problem.

Eating and drinking in hospital and care homes

Institutional settings are, paradoxically, a common place for malnutrition to develop or worsen, and a significant proportion of the harm is avoidable. Recognising the specific mechanisms is directly examinable, because they are all correctable through ward-level practice rather than through any specific treatment.

• Missed meals due to investigations or procedures - patients kept nil by mouth for a test that is repeatedly postponed, with no plan to make up the intake
• Unnecessary or prolonged nil-by-mouth status, often continued out of caution after the original reason has passed
• Food placed out of reach or left uncovered and cold, particularly for patients who cannot sit up or reach independently
• Lack of assistance at mealtimes for patients who need help to eat - a common problem where staffing is stretched and mealtimes are not protected
• Unfamiliar or culturally inappropriate food, or food that cannot be managed with poor dentition or ill-fitting dentures
• Being moved between wards at mealtimes, so a meal is simply missed with no record that it happened
• Restrictive therapeutic diets continued without ongoing justification, narrowing choice for a patient who is already eating poorly

Red flags

Prognosis

Malnutrition identified and treated early generally responds well to a structured, stepped nutritional intervention, with measurable improvement in strength, function and outcomes from other conditions. Untreated, it compounds frailty, increases complication and mortality risk across almost any concurrent illness, and is one of the more reliably reversible contributors to poor outcomes in older people - making routine screening and early intervention disproportionately high-value compared with many other interventions in geriatric medicine.

It is worth distinguishing malnutrition from cachexia, the disease-driven wasting seen in advanced cancer, heart failure, COPD and renal failure. Cachexia involves inflammatory cytokine-mediated catabolism of muscle and fat that does not fully reverse with feeding alone, so aggressive nutritional support in advanced cachexia rarely restores weight or function and can add burden without benefit. Recognising which process dominates prevents both therapeutic nihilism in treatable malnutrition and futile, burdensome intervention in end-stage cachexia.