Digestion and absorption of 2 fat emulsions with different droplet sizes in the human digestive tract

Background: The extent of fat emulsification affects the activity of digest ive lipases in vitro and may govern digestion and absorption of dietary fat . Objective: We investigated the effect of the fat globule size of 2 enteral emulsions on fat digestion and assimilation in humans. Design: Healthy subjects received intragastrically a coarse (10 mu m) and a fine (0.7 mu m) lipid emulsion of identical composition in random order. G astric and duodenal aspirates were collected throughout digestion to measur e changes in fat droplet size, gastric and pancreatic lipase activities, an d fat digestion. Blood lipids were measured postprandially for Eat assimila tion. Results: Despite an increase in droplet size in the stomach (2.75-6.20 mu m ). the fine emulsion retained droplets of smaller size and its lipolysis wa s greater than chat of the coarse emulsion (36.5% compared with 15.8%; P < 0.05). In the duodenum, lipolysis of the fine emulsion was on the whole hig her (73.3% compared with 46.3%). The overall 0-7-h plasma and chylomicron r esponses given by the areas under the curve were not significantly differen t between the emulsions, but the triacylglycerol peak was delayed with the fine emulsion (3 h 56 min compared with 2 h 50 min). Conclusions: Fat emulsions behave differently in the digestive tract depend ing on their initial physicochemical properties. A lower initial fat drople t size facilitates fat digestion by gastric lipase in the stomach and duode nal lipolysis. Overall fat assimilation in healthy subjects is not affected by differences in initial droplet size because of efficient fat digestion by pancreatic lipase in the small intestine. Nevertheless, these new observ ations could be of interest in the enteral nutrition of subjects suffering from pancreatic insufficiency.