Comparisons of the effects on satiety and eating behaviour of infusion of lipid into the different regions of the small intestine.

Abstract

SUMMARY Food intake and feelings of hunger and fullness were monitored in paired studies carried out in two groups of six healthy non-obese male volunteers during infusion of isotonic solutions of either a 50% corn oil emulsion or saline into the jejunum or into the ileum. Infusion of the lipid emulsion at a rate of 1-2 ml/min (4.9 kcal/min) into either the ileum or the jejunum significantly reduced the period of eating (p<0-01) and the quantity of food consumed (p<0O01), but neither affected the rates of drinking or the amount of fluid consumed. Infusion of the lipid emulsion into the jejunum also significantly reduced the sensations of hunger before the meal (p<005), and the rate of ingestion (p<0-01). Ileal infusion did not influence these indices. The results suggest that jejunal and ileal infusion of lipid reduces the size of the meal that could be consumed possibly by inhibiting gastric emptying. The alleviation of hunger before ingestion and the slower rate of eating, however, suggests that jejunal lipid activates an additional mechanism that influences the appetite centre in the hypothalamus directly.The mechanisms that regulate food intake and satiety in man are poorly understood, though on the basis of experiments carried out in rats, it has been suggested that food intake may be terminated by stimulation of nutrient receptors within the gastrointestinal tract.' In support of this hypothesis we have previously observed that infusion of lipid emulsion into the ileum reduced the amount of a meal consumed by normal volunteers2 whereas intravenous infusion of a similar lipid emulsion did not influence eating behaviour.2 The effect of ileal lipid on satiety is compatible with mediation by changes in gastric volume as it was associated with a delay in gastric emptying2 and a reduction in the capacity for food with no change in the rate of eating. In support of this idea, studies in rats have shown suppression of food intake during distension of the stomach with a balloon.3 It is possible however, that satiety and Address for correspondence: Dr N W Read, Sub-Department of Human Gastrointestinal Physiology and Nutrition, Royal Hallamshire Hospital, Sheffield, S10 2JF.Received for publication 11 September 1987. delayed gastric emptying after ileal infusion of lipid could be mediated by the central nervous system. Experiments in animals, however, suggest that the interaction of nutrients with receptors in the upper small intestine may reduce food intake by an action that is independent of gastric distension. Instillation of nutrients into the duodenum inhibits food intake in rats and monkeys equipped with gastric fistulae and triggers behaviour identical to that which occurs after a meal even though there is no food in the stomach.4T he aim of the study was to investigate possible satiety mechanisms triggered by receptors in the upper small intestine, by comparing the effects of infusion of lipid into the jejunum and ileum of normal human subjects on eating behaviour feelings of hunger and fullness. Methods S...

Effect of ileal fat perfusion on satiety and hormone release in healthy volunteers

“…This results in delivery of calories to the ileum of 0.6 kcal min À1 and 1.8 kcal min À1 for the 3 and 9 g of oil in total, respectively, both being much lower than the 4.9 kcal min À1 in the studies by Welch et al 8,12 The 3 g ileal fat resulted in a reduction in appetite and an increase in satiety. This effect was comparable with that induced by the 9 g of ileal fat.…”

“…22 A function of the ileal brake in the physiological regulation of gastrointestinal motility and secretion has been proposed. 23 The effect of lipids administered into the small intestine on satiety and food intake in humans has been studied previously by Welch et al 8,12 These authors demonstrated that infusion of fat in the ileum caused a reduction in food intake in healthy volunteers.…”

“…Evidence for a direct effect of the ileal brake on satiety and food intake in humans is limited to two publications from the same research group. 8,12 An ileal infusion of 370 kcal of lipids resulted in a significant reduction in hunger with a net decrease in caloric intake of 711 kcal. It should be noted that the amounts of fat used in these studies were high (41 g), and no studies have been performed on the satiating effect of ileal brake activation by very small amounts of fat.…”

Dose–response effects of a novel fat emulsion (Olibra™) on energy and macronutrient intakes up to 36 h post-consumption

“…Although current research suggests that fat is the least satiating of the macronutrients (Rolls & Hammer, 1995), the issue remains unresolved (Welch et al, 1988;de Graaf et al, 1992;Blundell et al, 1996). It is possible that methodological differences between study designs may have contributed to this controversy (Rolls et al, 1988;de Graaf et al, 1992).…”

“…Furthermore, different physicochemical properties of fats could influence their satiating properties. These include fatty acid chain length (Bach et al, 1996;Stubbs & Harbon, 1996;Van Wymelbeke et al, 1998), degree of fatty acid unsaturation (Shimomura et al, 1990;Lawton et al, 1997;Kamphuis et al, 2001), degree of emulsification (Welch et al, 1985(Welch et al, , 1988 and emulsion stability (Armand et al, 1992). In this context it has recently been shown that a fat emulsion (Olibra TM ) formulated from palm oil and oat oil fractions significantly decreased energy and macronutrient intakes in lean, overweight and obese subjects up to 36 h post-consumption (Burns et al, 2000(Burns et al, , 2001.…”