Calories: Early nutritional support in the critically ill


There are two main ways to way to feed seriously ill patients who cannot eat for themselves: either directly into the bloodstream (the intravenous or parenteral route) or into the stomach (via a tube inserted through the mouth, nose or through the skin of the abdomen – the enteral route). It is not known which is best, particularly during the first few days of a serious illness. The aim of this study was to investigate which route is best for patients who have just been admitted to an intensive care unit of the UK NHS. We also measured the costs of each method.


A total of 2400 patients from 33 NHS hospitals took part in the study. Their feeding route was chosen at random. A total of 1200 patients were fed intravenously (the parenteral route) and 1200 patients were fed into the stomach (the enteral route).


There was no significant difference between the groups in the number of patients who died at 1, 3 or 12 months. Patients who received nutritional support via the stomach had more vomiting and more diarrhoea. At 12 months, the overall costs of intravenous feeding were £28,354 per patient and £26,775 for feeding via the stomach. The additional costs of intravenous feeding were not justified by better outcomes.


The results of the study support continuing to feed seriously ill patients via the stomach when this is possible.

Who led the study?

  • Professor Kathy Rowan, ICNARC
  • Professor Michael Mythen, University College Hospital, London

This study was funded by the National Institute for Health Research (NIHR) – Health Technology Assessment (HTA) Programme (Project: 07/52/03)


Harvey SE, Parrott F, Harrison DA, Sadique MZ, Grieve RD, Canter RR, McLennan BK, Tan JC, Bear DE, Segaran E, Beale R, Bellingan G, Leonard R, Mythen MG, Rowan KM. A multicentre, randomised controlled trial comparing the clinical effectiveness and cost-effectiveness of early nutritional support via the parenteral versus the enteral route in critically ill patients (CALORIES). Health Technol Assess 2016; 20(28):1-144.

Sadique Z, Grieve R, Harrison D, Rowan K. Cost-Effectiveness Of Early Parenteral Versus Enteral Nutrition In Critically Ill Patients. Value Health 2015; 18(7):A532.

Harvey SE, Parrott F, Harrison DA, Mythen M, Rowan KM. The CALORIES trial: statistical analysis plan. Crit Care Resusc 2014; 16(4):248-54.

Harvey SE, Parrott F, Harrison DA, Bear DE, Segaran E, Beale R, Bellingan G, Leonard R, Mythen MG, Rowan KM. Trial of the route of early nutritional support in critically ill adults. N Engl J Med 2014; 371(18):1673-84.