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Adult nutrition

Background knowledge

Normal requirements for hospital patients

Dependent on patient weight:                                  

  • Energy: 30kcal/kg/day
  • Protein: 0.8-1g/kg/day
  • Fluid: 30-35ml/kg/day

e.g. for an average 70kg patient over 24 hours: energy 2100kcal, protein 56-70g, fluid 2.1-2.45L 

Assessing nutritional status

  • Malnutrition Universal Screening Tool (MUST) score: 0 = low risk; 1 = medium risk (observe); 2 or more = high risk (treat). Scoring takes into account BMI, unplanned weight loss, and whether patient is acutely ill and has had/will have no nutritional intake for >5 days (Elia et al. 2003)
  • BMI
  • History
  • Nutritional status exam
  • Bloods: haemoglobin, electrolytes (including Mg2+, PO43-, Ca2+), LFTs (including albumin), haematinics (B12, folate, ferritin)


  • Meals should ideally contain 650-850kcal 
  • A food guide should be used to calculate energy and protein intake

Oral supplements

Nutritional drinks

Quantity required is determined by calculating the difference between the patient’s daily calorie requirement and their intake. 

 Energy (kcal)Carbohydrate (g)Protein (g)Fat (g)
Fortisip Extra (200ml milkshake)320 362011
Fortisip Compact (125ml milkshake) – similar contents in smaller volume300371212
Fortisip Multi Fibre (200ml milkshake) – with  5g fibre to help bowel function300371212
Fortijuice (200ml juice) – avoid in diabetes (contains sugar)3006780
Nestlé Resource Energy (200ml milkshake)300 421110
Nestlé Build Up soup (49g sachet)200 2776.9
Nutricia PreOp (200ml clear drink) – 2 taken 2 hours pre-op for major elective operations1002500

Additional micronutrients to consider

  • Vitamin supplements
    • Sanatogen multivitamin tablets
    • Oral Vitamin B Compound Strong + thiamine 
    • Pabrinex (IV equivalent of oral Vitamin B Compound Strong + thiamine) – consider using IV for first 3 days before changing to oral if patient has anorexia nervosa, chronic alcoholism or very high refeeding risk
  • Electrolyte supplements (replace if low) 
    • Potassium 
    • Phosphate
    • Magnesium 

Enteric feeds

Enteric feeds may be required when oral intake is likely to be absent for >5-7 days and gut is functioning 

Administration methods

  • Fine-bore nasogastric (NG) tube – for short-term use
  • Nasojejunal (NJ) tube – if problems with gastric reflux or delayed gastric emptying
  • Percutaneous gastrostomy/jejunostomy tube – for longer-term feeding, i.e. >4-6 weeks, or if there is a mechanical swallowing obstruction
  • May be inserted:
    • Endoscopically: percutaneous endoscopic gastrostomy/ jejunostomy (PEG/J) – most
    • Radiologically: radiologically inserted gastrostomy (RIG) – if patient cannot swallow
    • Surgically – if having other surgery, tube may be placed at the same time

Matching requirements

  • Most feeds contain 1kcal/ml and are nutritionally complete (hence, 30ml/kg/day will match requirements, but start slower in patients at risk of re-feeding syndrome – see below)
  • Reduce feed if they are also eating (deduct their oral intake of calories)
  • Exact feed choice is influenced by nutritional requirements, absorption/motility abnormalities, diarrhoeal loss, and presence of liver/renal impairment

Types of feed

  • Polymeric feeds (polypeptides), e.g. Nutrison, Nutrison Multifibre – most commonly used
  • Pre-digested feeds (small peptides) – better absorbed, for maldigestive patients, patients with short gut or pancreatic insufficiency
  • Disease-specific and pharmaco-nutrient feeds – for patients with liver/renal impairment 

Administration options

  • Boluses (e.g. 200-400ml over 15-60 minutes at regular intervals) – more physiological but can cause dumping syndrome
  • Intermittent infusion (breaks of 6 or more hours depending on requirements) – most commonly used
  • Continuous infusion – used for very ill patients

Giving drugs via enteric tubes

  • Use solutions where possible
  • Some tablets can be crushed and some capsules can be opened (check with pharmacist)
  • Tablets which cannot be crushed: modified release tablets, enteric coated tablets

Parenteral nutrition

Parenteral nutrition may be required in intestinal failure (acute or chronic) and is given via central venous line

  • Parenteral nutrition (PN) – if also feeding patient by other methods
  • Total parenteral nutrition (TPN) – only IV feeding

Re-feeding syndrome

  • Feeding malnourished patients can cause an insulin surge and activation of cellular membrane pumps. This can drop various serum electrolyte levels (especially K+, PO43-, Mg2+), which can lead to arrhythmias and death.
  • Risk factors
    • 1 or more: BMI ≤15, weight loss >15% over 3-6 months, poor intake for >10 days, low electrolytes
    • 2 or more: BMI <18.5, weight loss >10% over 3-6 months, poor intake for >5 days, alcohol excess
  • In anyone who is at risk:
    • Start feeding at 10kcal/kg/day (5kcal/kg/day if very malnourished) and build up gradually to meet requirements over ~1 week
    • Check K+, PO43-, Mg2+ at least daily at first
    • Check capillary glucose several times per day
    • Monitor fluid balance and restore circulatory volume (although be cautious of dextrose/glucose containing fluids)
    • Give supplements
      • Oral Vitamin B Compound Strong and thiamine (consider 3 days IV Pabrinex first if very high risk) 
      • Multivitamin supplement
      • Electrolyte supplements 
  • Management
    • Continue low level of feed 
    • Aggressively replace all low electrolytes IV (K+, PO43-, Mg2+)
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