Glucose or fat as a nonprotein energy source? A controlled clinical trial in gastroenterological patients requiring intravenous nutrition.

The best nonprotein energy source for routine use in patients receiving intravenous nutrition (IVN) for short periods of time is not known. In particular the relative merits of glucose and fat remain controversial. The present study was undertaken to determine if a quantitative difference in the ability to retain nitrogen could be documented between these two energy sources. In a prospective study of two comparable groups of 16 gastroenterologic patients who received IVN for 2 wk the changes in body weight, fat, water, and protein that occurred were measured. The only difference in the IVN between the groups was the nonprotein energy source. Group I received hypertonic glucose alone (49.2 +/- 7.9 kcal/kg day), and group II received an intravenous fat emulsion (60% of the nonprotein energy) in addition to hypertonic glucose (51.5 +/- 5.0 kcal/kg/day). Significant weight gain occurred in both groups (p < 0.001). In group I this was acounted for by gains of water (p < 0.02) and fat (p < 0.01) but not of protein. Patients receiving glucose together with fat (group II) gained protein (p < 0.02), but the gains of fat and water were not significant. Our study shows that protein repletion was achieved with an intravenous fat emulsion over a 2-wk period and the problems of water retention which occurred in the patients fed with glucose alone was not present. The results suggest that the fat in conjunction with glucose may be more effective as an energy source than equicaloric amounts of glucose alone in the type of patients we have studied.