Key Facts

Malnutrition and sarcopenia are interrelated conditions that significantly worsen outcomes in older adults. Both are modifiable with appropriate nutrition and exercise.

Epidemiology

• Malnutrition: ~3 million affected in the UK; 30% of hospital admissions
• Sarcopenia: 10-30% of community-dwelling >60; increases with age
• Both contribute to frailty, falls, functional decline, and mortality
• Malnutrition costs the NHS approximately £20 billion/year

Aetiology

• Malnutrition causes: reduced intake (poor dentition, dysphagia, depression, dementia, poverty), increased requirements (acute illness, infection, cancer), impaired absorption (malabsorption syndromes)
• Sarcopenia causes: ageing (primary), inactivity, malnutrition, chronic disease (secondary)
• Risk factors: hospitalisation, social isolation, polypharmacy, chronic disease

Pathophysiology

• Malnutrition: negative energy and protein balance → loss of fat and muscle mass → impaired immune function, wound healing, and organ function
• Sarcopenia: multifactorial muscle loss — reduced protein synthesis, increased proteolysis (ubiquitin-proteasome pathway), mitochondrial dysfunction, hormonal changes (reduced testosterone, GH, IGF-1), chronic inflammation (IL-6, TNF-α), neuronal loss (motor unit remodelling)

Malnutrition

• Unintentional weight loss (>5% in 3 months or >10% in 6 months)
• BMI <18.5 kg/m² (or <20 in elderly)
• Loose clothing, visible wasting
• Fatigue, weakness
• Poor wound healing
• Increased susceptibility to infection
• Oedema (hypoalbuminaemia)

Sarcopenia

• Reduced grip strength
• Slow gait speed (<0.8 m/s)
• Difficulty rising from chair, climbing stairs
• Falls and fractures
• Functional decline

Red Flags

• Unintentional weight loss >5% in 3 months (consider malignancy)
• Dysphagia (oesophageal/oropharyngeal pathology)
• BMI <16 (severe malnutrition; refeeding risk)
• Progressive muscle weakness (consider myopathy, myositis, MND)
• Malabsorption symptoms (steatorrhoea, deficiency states)

Bedside

• MUST screening: BMI + unplanned weight loss + acute disease effect → risk score (0 = low, 1 = medium, ≥2 = high)
• Weight, height, BMI
• Grip strength (dynamometer): cut-offs for sarcopenia — <27kg men, <16kg women
• Gait speed (<0.8 m/s abnormal)
• Chair stand test (5 stands)
• Nutritional intake assessment (food diary)
• Oral health assessment (dentition, oral candida)
• Swallowing screen

Bloods

• Albumin (indicator of inflammation/acute phase, not purely nutritional)
• Pre-albumin (shorter half-life; better nutritional marker)
• FBC, ferritin, B12, folate (micronutrient deficiencies)
• Vitamin D, calcium, magnesium, zinc
• U&Es, phosphate (refeeding risk)
• TFTs, CRP

Imaging

• DEXA (whole body): gold standard for muscle mass measurement (appendicular skeletal muscle mass index)
• Bioelectrical impedance analysis (BIA): alternative for muscle mass estimation
• CT/MRI: can assess muscle cross-sectional area (research/specialist)

Special Tests

• SARC-F questionnaire: screening tool for sarcopenia (5 questions)
• Swallow assessment (SALT) if dysphagia suspected
• Malabsorption screen: faecal elastase, tTG antibodies

Non-pharmacological

• Dietary optimisation: energy-dense, protein-rich diet; fortified foods; little and often
  • Protein: 1.0-1.2 g/kg/day (healthy older); 1.2-1.5 g/kg/day (malnourished/acutely ill)
  • Distribute protein across all meals (25-30g per meal for optimal muscle protein synthesis)
• Oral nutritional supplements (ONS): Fortisip Compact Protein, Ensure, Complan; 300-600 kcal/day supplementation
• Resistance exercise: most effective single intervention for sarcopenia
  • Progressive resistance training 2-3 times/week
  • Combined with aerobic and balance exercise
• Mealtime support: assisted feeding, protected mealtimes, social dining
• Treat underlying causes: dental treatment, manage dysphagia (SALT, modified diet), treat depression, review medications affecting appetite

Pharmacological

• Micronutrient supplementation: vitamin D 800-1,000 IU daily (if deficient), iron, B12, folate as indicated
• Appetite stimulants: limited evidence; megestrol acetate (palliative setting only — thrombosis risk)
• Refeeding syndrome prevention: start feeding slowly (10 kcal/kg/day), supplement thiamine 200-300mg IV before feeding, monitor K+, PO4³⁻, Mg²⁺ daily for first week

Surgical/Interventional

• Nasogastric (NG) feeding: short-term if oral intake inadequate
• PEG (percutaneous endoscopic gastrostomy): if long-term enteral feeding needed (>4 weeks)
• Parenteral nutrition (TPN): if gut not functioning (intestinal failure)

Referral Criteria

• MUST score ≥2: dietitian referral
• Dysphagia: SALT referral
• Severe malnutrition (BMI <16): nutrition support team
• Suspected sarcopenia with functional decline: geriatric assessment
• Suspected malabsorption: gastroenterology

• Malnutrition increases hospital mortality by 2-3×; prolongs LOS by 30%; increases readmission
• ONS in malnourished patients reduces mortality (NNT ~24) and complications
• Sarcopenia is independently associated with 2× mortality and 3× fall risk
• Resistance exercise + protein: can reverse sarcopenia in early stages
• Refeeding syndrome: can be fatal if unrecognised (cardiac arrhythmias, respiratory failure)
• Both conditions are modifiable with appropriate intervention

MUST (Malnutrition Universal Screening Tool)

EWGSOP2 Sarcopenia Criteria (2019)