Background and AimsEnergy and protein provision for critically ill patients who receive oral nutrition often falls below recommended targets. We compared characteristics and nutrition processes during hospital stay (within and post‐intensive care unit [ICU] stay) of those who received oral nutrition as the sole nutrition source to those who first commenced enteral (EN) or parenteral nutrition (PN) within an Australian or New Zealand (ANZ) ICU.MethodsMulticentre, observational study of routine nutrition care in 44 hospitals across ANZ, including adult patients within ICU admitted for at least 48 h. Those receiving oral nutrition as the sole source of nutrition (with or without oral nutrition supplements) were included in the ‘oral nutrition’ group and those who first received EN and/or PN in the ICU as the ‘EN/PN group’. The primary outcome was median daily energy delivery in ICU. Data are presented as number (%) or median [interquartile range].ResultsOf the 409 patients enroled, median [IQR] age was 64 [51–74] years and 257 patients (62%) were male. APACHE II score, use of invasive ventilation and hospital length of stay (LOS) were all lower in those receiving oral nutrition (n = 200) compared to those receiving EN/PN (n = 209). In ICU, 63 (31.5%) and 169 (81%) (p < 0.001), patients who were receiving oral nutrition and in the EN/PN group received a nutrition assessment, respectively. Oral nutrition supplements were provided for 40 (20%) patients in the oral nutrition group and 31 of 94 (33%) of those receiving oral nutrition in the EN/PN group (p = 0.019). Energy and protein intake in ICU for the oral nutrition group was 716 [597–1069] kcal/day and 37 [19–46] g/day versus 1158 [664–1583] kcal/day and 57 [31–77] g/day for those receiving EN/PN (p = 0.020 energy, p = 0.016 protein). Quantification of oral nutrition was attempted in 78/294 (27%) patients in ICU and completed on 27/78 (36%) occasions. On the ward, attempts were made for 120/273 (44%) patients, with 60/120 (50%) complete.ConclusionPatients who received oral nutrition as the sole nutrition source in ICU had lower illness severity, rates of nutrition assessment and provision of oral supplements compared to those who first received EN/PN. Quantification of oral nutrition was often incomplete for all patients in ICU and on the ward.