Impact of Food Combination on Starch Digestion and Gastric Processing

Overview

The results of our in vitro studies strengthen the hypothesis that the contribution of salivary alpha-amylase to starch digestion has been underrated and that this enzyme can play an important role in this process. As a result, its inhibition could constitute an opportunity to reduce the glycemic response elicited by starch-rich foods. The main goal of this study is to verify whether inhibiting salivary alpha-amylase upon the consumption of starchy foods, can have an impact on the postprandial glycemic response, and/or satiety.

The main objective of this work was to test the impact of adding black tea or lemon juice to a starch-rich meal on postprandial plasma glucose concentrations and on energy intake in healthy humans. This study was divided into two parts. The objective of part 1 was to determine the effect of pairing a starch-rich food with water, black tea or lemon juice on postprandial plasma glucose and energy intake in healthy humans. This study was conducted in semi-controlled conditions. The three test meals (equal portions of bread (100 g) and 250 mL of either water, black tea or lemon juice) were consumed as breakfast (after a 10-h fast) on independent days and in a randomised order. Capillary blood glucose concentrations were self-monitored using the finger-prick method at pre-defined time-points during 180 min. Ad libitum energy intake was assessed 3 hours later. The main objective of part 2 was to investigate whether the gastric emptying patterns remain, or not, the same when a bread meal is paired with water, tea, and lemon juice. Blood glucose response and satiety perceptions were also monitored. The test meals were similar to those in branch 1, except that the meals were supplemented with 20 peas, which the subjects were asked to swallow at the end (with half of the beverage provided) without chewing. These peas conferred a distinct contrast in MRI scans and could be used as stomach motility and gastric mixing tracers in MRI images. Capillary blood glucose concentrations were determined using the finger-prick method at pre-defined time-points during 180 min. Visual analogue scales were used to assess satiety-related perceptions. Volunteer recruitment was conducted independently for each part of the study and volunteers were allowed to participate in one part of the study only. Data collected in each part of the study was analysed independently.