Comparison of proprietary elemental and whole-protein diets in unconscious patients with head injury

Forty men who had sustained head injury were randomly assigned to one of five groups to receive 0.2 g nitrogen/kg body weight/day as either an elemental or a whole-protein diet. Three proprietary elemental and two whole-protein diets were compared. The mean daily nitrogen intake was below 0.2 g/kg in all groups, and was significantly lower in the groups receiving elemental compared with whole-protein diets. Energy intake was significantly different only between one group receiving an elemental and one receiving a whole-protein diet. Mean daily urinary nitrogen excretion was significantly lower in the groups receiving elemental diets, and mean daily nitrogen balance was negative in all groups except one receiving a whole-protein diet. Reduced nitrogen intakes occurred particularly with the elemental diets, which often provoked reflex vomiting or gastric stasis. The need to introduce diets at reduced strength made a negative balance almost inevitable, but nutritional balance seemed to be more readily achieved with the whole-protein diets. More work is needed to assess the relative merits of these proprietary diets compared with tube feeds prepared in hospitals.