Addition of different fats to a carbohydrate food: Impact on gastric emptying, glycaemic and satiety responses and comparison with in vitro digestion

In vitro, the addition of lipids to a carbohydrate food has been found to increase the digestibility of starch. In contrast, in vivo studies have shown that the addition of fat to a food can reduce the glycaemic response (GR). The aim of this study was to assess if delayed gastric emptying (GE) causes reduced GR with the addition of lipids to a carbohydrate food and if a relationship between GR and in vitro digestion of starch exists for high fat foods. Ten healthy volunteers were tested on five occasions after consuming pancakes containing 50 g of available carbohydrate and 202 kcal of sunflower oil, olive oil, butter, medium chain triglyceride (MCT) oil or a control containing no oil. GR was measured using fingerpick blood samples, satiety using visual analogue scales and GE using the C-13 octanoic acid breath test. There was a significant difference in GR between the different pancake breakfasts (p=0.05). The highest GR was observed following the control pancakes and the lowest following the olive oil pancakes. There were significant differences in GE half time, lag phase and ascension time (p<0.05) between the different pancakes with the control pancakes having the shortest GE time and the MCT pancakes the longest. There was a significant difference in satiety parameters fullness (p=0.003) and prospective consumption (p=0.050), with satiety being lowest following the control pancakes. There was a significant inverse correlation between the GR and all satiety parameters. A significant inverse correlation (p=0.009) was also observed between the digestibility of starch in vitro and GR in vivo. The paper indicates that the digestibility of starch in vitro does not predict the GR for high fat containing foods. (C) 2012 Elsevier Ltd. All rights reserved.