Proteins – Is more better for all?

Enteral or Parenteral – Any difference?

(Olav Rooyackers)

Clear ESPEN recommendations: Normal way of eating is best = Oral > EN > PN

If EN / PN done well, with equal calories delivered — NO significant difference in outcomes of mortality 

Small RCT by Ferrie et al: PN with higher levels of amino acids (1.2g/kg) give small improvements in different measures e.g. grip strength, muscle thickness compared to PN with lower levels of amino acids (0.8g/kg)

FEED trial: to compare effect of standard EN formula vs. EN formula with higher protein supplementation on muscle mass and strength amongst other outcomes

Both EN and PN protein supplementation likely to affect muscle in some way.

  • currently no direct comparison between EN and PN in ICU pts
  • EN protein is partly taken up by the gut; PN protein bypasses splanchnic circulation – does this feed muscles directly and is it better??
  • Liebau et al. Critically ill pts handle protein differently – the critically ill gut is ‘selfish’ and extracts more amino acids compared to the gut in healthy volunteers, though initiation of EN causes a small but detectable improvement in whole body protein balance

Small study in 14 elderly pts comparing EN and PN amino acids administration showed muscle protein synthesis was not affected by route of administration

  • note: high doses amino acids used, unclear if a difference in muscle protein synthesis stimulation would be seen at lower doses of EN and PN administration


Relation between protein intakes and frailty

(Zudin A. Puthucheary)

Frailty is a complex interplay of factors: age, comorbidity, socio-economic status

Early days of critical illness: Immobility + Illness –> muscle protein synthesis (MPS) is decreased

Ageing population – increased age of pts admitted to ICU

  • MPS rate is similar in young and old men- however the MPS RESPONSE to exercise differs with age
  • Following resistance exercise in younger men, there is faster increase in MPS, with longer duration of persistent MPS compared to older men


Comorbidities contribute to Frailty: most studies performed in COPD pts


  • By day 9 of critical illness, Age and Premorbid health become more important in determining outcome

Socio-economic status is NOT corrected for in any trials for Nutrition

  • related to disparity in nutrition
  • significant contributor to frailty
  • pts below poverty threshold unlikely to have balanced diet
  • elderly males more likely to have energy dense meals (high CHO, low protein)


Functional assessment in 12 questions on social history

Note: pts usually not asked about shopping, finances, meal prep but these relate to ‘nutritional disability’!


Should protein and energy goals be separated?

(Jan Wernerman)

Short answer: Yes, but it’s complicated

No RCTs, only circumstantial evidence


How much room do we have for nutritional volume without causing overload?

  • many commercial formulae available, commonly 25kcal/gram protein

  • for most pts admitted >1 week, needing >2500kcal, a uniform algorithm can be used
  • for outliers (length of admission, body weight, energy expenditure) consider the patient separately with individualised feeding prescription


No hard evidence that protein under- or over-feeding do harm on short and medium term basis (very little long term data)

Avoid deliberate excessive protein feeding especially in malnourished pts as they have been protein-deficient for long time and may be at greater risk of harm from protein-overfeeding

Observational data in critically ill pts: more protein feeding appears to improve survival

Monitoring protein feeding:

  • Use nutrition chart and serum urea
  • imaging muscle mass with ultrasound or CT are technically difficult to interpret due to fluctuations in muscle water content