Effects of aging and gastric lipolysis on gastric emptying of lipid in liquid meal.

Lipid delays gastric emptying, and aging is associated with changes in gastric motor function and transit. However, little is known about the effect of lipid on gastric emptying time in the elderly. To determine the effect of aging on lipid gastric emptying, we used electrical impedance tomography (EIT) to study gastric emptying of liquid meals with or without lipid in five young (23.0 +/- 0.6 years, mean +/- SEM) and six elderly (73.3 +/- 1.6 years) healthy male volunteers. These subjects drank 400 ml of non-lipid soup (triglycerides, 0 g) or lipid soup (triglycerides, 24.6g) in liquid test meals. To study the effect of lipolysis in the stomach, a liquid test meal containing 240mg of lipase in the lipid soup was also administered. Plasma cholecystokinin (CCK) concentration was measured by specific radioimmunoassay before and 30 min after the ingestion of a test meal. The gastric emptying time of the lipid soup was longer in the elderly than in the young subjects, and the time was significantly longer for lipid soup than for nonlipid soup (P < 0.05) in both the young and elderly subjects. Gastric emptying time for non-lipid soup was not significantly different between the elderly and young subjects. The administration of lipase shortened the gastric emptying time for lipid in both the elderly and the young subjects. Basal CCK concentration was significantly higher in the elderly than in the young subjects. However, there was no relationship between gastric emptying time and plasma CCK concentration after the ingestion of a test meal in the subjects overall. In conclusion, the delaying effect of lipid on gastric emptying is increased in the elderly, and the administration of lipase accelerates the emptying of lipid from the stomach.