Meal Energy Density as a Determinant of Postprandial Gastrointestinal Adaptation in Man

Abstract

The relationships between the meal energy density and postprandial gastric emptying, intestinal propulsion and absorption, and pancreaticobiliary secretions were investigated. Nine different 300-ml liquid test meals with energy densities ranging from 2.5 to 7.2 MJ 1^-1 were studied by means of a multiple-indicator dilution technique. The higher the energy density of the meal, the slower the gastric emptying of the test meal marker (P < 0.01). Despite slowing of gastric emptying of the meal marker the higher the energy density of the meal, the more energy was emptied to the duodenum during the 1st h after meal intake (P<0.01). The small-intestinal transit time for the mid-portion of the meal correlated positively with energy density of the test meal (P < 0.05). Despite the prolonged time for transit through the jejunal test segment after meals with high energy density, the fractional absorption of energy varied only 50-70%, with no correlation to the energy density of the meal. As a consequence, more energy passed unabsorbed from the test segment to lower parts of the intestine after meals with high energy density (P < 0.05). We conclude that the energy density of a liquid meal is a strong determinant for the subsequent gastrointestinal adaptation. This relates not only to gastric emptying but also to intestinal transit and absorption of nutrients. The early onset of regulation suggests a role for the gastrointestinal tract in modulating the availability of systemic energy, which might be of importance for short-term regulation of food intake.

Key Words:

• Amylase
• energy density
• gastric emptying
• gastric secretion
• intestinal absorption
• intestinal motility