In vivo imaging of intragastric gelation and its effect on satiety in humans.
ABSTRACT Previous studies indicated that physical characteristics of food influence satiety, but the relative importance of the oral, gastric, and intestinal behaviors of the food is unclear. The aim of this study was to investigate the satiating effects of 2 types of alginates, which gel weakly or strongly on exposure to acid, compared with guar gum whose viscosity is unaffected by acid. Subjects (n = 12; 3 men, 9 women) ingested a 325-mL sweetened, milk-based meal replacer beverage on 4 separate occasions, either alone as a control or including 1% by weight alginate or guar gum. Intragastric gelling, gastric emptying, and meal dilution were assessed by serial MRI while satiety was recorded for 4 h. MR images showed that all of the meals became heterogeneous in the stomach except for guar, which remained homogeneous. The alginate meals formed lumps in the stomach, with the strong-gelling alginate producing the largest volume. Although gastric emptying was similar for all 4 meals, the sense of fullness at the same gastric volume was significantly greater for all 3 viscous meals than for the control. Compared with the control meal, the strong-gelling alginate (P = 0.031) and guar (P = 0.041) meals increased fullness at 115 min, and the strong-gelling alginate decreased hunger by the 115-min (P = 0.041) and 240-min (P = 0.041) time points. Agents that gel on contact with acid may be useful additions to weight-reducing diets. We hypothesize that this effect is due to distension in the gastric antrum and/or altered transport of nutrients to the small intestine in the lumps.
Article: Intragastric layering of lipids delays lipid absorption and increases plasma CCK but has minor effects on gastric emptying and appetite.[show abstract] [hide abstract]
ABSTRACT: Intestinal intubation studies have demonstrated that lipids induce satiety, but the contribution of lipid processing by the stomach on satiety remains poorly understood. In this explorative, randomized, placebo-controlled, crossover study we tested whether delayed lipid absorption, increased cholecystokinin (CCK), decelerated gastric emptying (GE), and increased satiety can be achieved by controlling lipid distribution in the stomach. Six healthy men were intubated nasogastrically. Two treatments were performed and repeated in duplicate. In the oil-on-top treatment (OT), subjects received a fat-free liquid meal (LM, 325 ml, 145 kcal) followed by intragastric infusion of 4 g of high-oleic-acid rapeseed oil (4.6 ml, 36 kcal) labeled with 77 mg glyceryl-[(13)C]trioleate. In the emulsion treatment (EM, control), 4 g of labeled rapeseed oil was incorporated into the LM (325 ml, 181 kcal); 4.6 ml of saline was infused as a control. In OT and EM a second LM was consumed at time t = 270 min. Plasma (13)C-C18:1, CCK and satiety were measured over 480 min. GE was determined by the paracetamol absorption test. OT delayed oleic acid absorption shown by an increased lag time of absorption (EM: 37 +/- 7 min; OT: 75 +/- 10 min; P < 0.01) and time at maximum concentration (EM: 162 +/- 18 min; OT: 280 +/- 33 min; P = 0.01). OT released more CCK than EM (P = 0.03), including increased CCK after the second meal. OT accelerated initial GE until 30 min postprandial. OT showed a tendency (P = 0.06) to suppress hunger and increase satiety and fullness 120-270 min postprandially. The results demonstrate that low amounts of lipids, when separated from the aqueous phase of a meal, delay lipid absorption and increase CCK. An escalating-dose study should determine whether this could have implications for the development of weight-control foods.AJP Gastrointestinal and Liver Physiology 04/2009; 296(5):G982-91. · 3.43 Impact Factor
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ABSTRACT: The aim of this paper is to describe and discuss relevant aspects of the assessment of physiological functions – and related biomarkers – implicated in the regulation of appetite in humans. A short introduction provides the background and the present state of biomarker research as related to satiety and appetite. The main focus of the paper is on the gastrointestinal tract and its functions and biomarkers related to appetite for which sufficient data are available in human studies. The first section describes how gastric emptying, stomach distension and gut motility influence appetite; the second part describes how selected gastrointestinal peptides are involved in the control of satiety and appetite (ghrelin, cholecystokinin, glucagon-like peptide, peptide tyrosin-tyrosin) and can be used as potential biomarkers. For both sections, methodological aspects (adequacy, accuracy and limitation of the methods) are described. The last section focuses on new developments in techniques and methods for the assessment of physiological targets involved in appetite regulation (including brain imaging, interesting new experimental approaches, targets and markers). The conclusion estimates the relevance of selected biomarkers as representative markers of appetite regulation, in view of the current state of the art.Obesity Reviews 11 (2010) 3.
Nutrition Journal 10/2009; · 2.48 Impact Factor