Dose, composition, and side effects of feeds

Vivian Imbriotis | June 22, 2026

Feeding can be performed enterally (via the GI tract) or parenterally (intravenously, bypassing the GI tract).


Parenteral feeds

Dose - calculated to meet nutritional requirements (predictive eqn or indirect calorimetry). Empirically:

  • Energy 25kcal/kg/day
  • Protein 1.5g/kg/day
  • 30% of remaining energy from fats (~1g/kg/day)
  • 70% remaining energy from CHOs (~4g/kg/day)
  • Water 30ml/kg/day

Composition

  • 2L bag foiled to protect from UV
  • 1000 kcal/L
  • Hyperosmolar ~2000mOsm/L
  • Glucose 100-175g/L
  • Protein (as amino acid solution containing all 9 essential amino acids) 35-50g/L
  • Fats (as intralipid from soybean oil) 25-50g/L
  • Electrolytes: Na 35mM, K 30mM, Mg 5mM, PO4 10mM
  • Vitamins: added to RDI (Fat soluble ADEK, water soluble C, B complex)
  • Trace elements: added to RDI (copper, iodine, zinc etc)

Adverse effects

  • Refeeding syndrome
  • LFT derangement
  • Trace element deficiency
  • Hyperglycaemia, hypercholesterolaemia, hypertriglyceridemia (can \(\to\) pancreatitis)
  • Catheter related sepsis (most TPN requires central access)


Enteral feeds

Dose - calculated to meet nutritional requirements (predictive eqn or indirect calorimetry). Empirically:

  • Energy 25kcal/kg/day
  • Protein 1.5g/kg/day
  • 30% of remaining energy from fats (~1g/kg/day)
  • 70% remaining energy from CHOs (~4g/kg/day)
  • Typically 40-80ml/hr

Composition

  • 1L bags, 1-2kcal/ml
  • 80% water
  • Protein (caesin) - 15% of calories (35-50g/L); high-protein formulation up to 100g/L
  • CHOs (maltodextrin) 60% calories (100-175g/L)
  • Fats (sunflower/canola oil) 30% of calories (25-50 g/L)
  • isoosmolar (can be concentrated up to 600mOsm/L)
  • Vitamins added to RDI (fat soluable - ADEK, water soluble - C and B-complex)
  • Minerals (Na 2mmol/kg/day, K 1mmol/kg/day, Ca/Mg/PO4 all 0.1mmol/kg/day)
  • Trace elements to RDI (Copper, iodine, zinc, etc)

Adverse effects

  • Acute: refeeding syndrome, hyperglycemia, hypertrigyceridaemia, diarrhoea, nausea
  • Mid-term: micronutrient deficiency, over- or under-feeding as requirements change
  • Chronic: malnutrition, obesity, metabolic syndrome, sarcopenia, reduced quality of life