Characterization of emulsions and lipolysis of dietary lipids in the human stomach.
Fasting subjects were intragastrically intubated and received a coarsely emulsified test meal. Gastric aspirates were collected after 1, 2, 3, and 4 h. During digestion in the stomach, unemulsified lipids (> or = 100 microns) represented a minor fraction. A significant amount of the large 70- to 100-microns lipid droplets disappeared, and fine 1- to 10-microns droplets were generated. The median lipid droplet diameter significantly decreased (21.9 vs. 52.9 microns) after 1 h and kept intermediate values for longer periods of time. The emulsion surface area was 100-120 m2/l and was basically provided by 1- to 100-microns droplets. Lipolysis catalyzed by gastric lipase primarily occurred within the first hour of digestion (11.9%). Smaller droplets were enriched in triglyceride lipolytic products. The free fatty acid concentrations were in the range of 5.6-8.2 mM over 1-4 h. The present finding demonstrates for the first time that in the human stomach most dietary lipids are present in the form of emulsified droplets, in the range of 20-40 microns, and that gastric lipolysis can help to increase emulsification in the stomach.
Armand
M
M
Institut National de la Santé et de la Recherche Médicale U. 130, Marseille, France.
Borel
P
P
Dubois
C
C
Senft
M
M
Peyrot
J
J
Salducci
J
J
Lafont
H
H
Lairon
D
D
D004041:Dietary Fats / Q000378:metabolism*; D004655:Emulsions; D005223:Fats / Q000737:chemistry*; D005753:Gastric Mucosa / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000378:metabolism; D008066:Lipolysis; D013395:Sucrose / Q000378:metabolism; D014018:Tissue Distribution; D014280:Triglycerides / Q000378:metabolism
D004041:Dietary Fats; D004655:Emulsions; D005223:Fats; D014280:Triglycerides; D013395:Sucrose; D008049:Lipase