Oatmeal particle size alters glycemic index but not as a function of gastric emptying rate

Abstract

The aim of this study was to determine the extent to which oat particle size in a porridge could alter glucose absorption, gastric emptying, gastrointestinal hormone response, and subjective feelings of appetite and satiety. Porridge was prepared from either oat flakes or oat flour with the same protein, fat, carbohydrate, and mass. These were fed to eight volunteers on separate days in a crossover study, and subjective appetite ratings, gastric contents, and plasma glucose, insulin, and gastrointestinal hormones were determined over a period of 3 h. The flake porridge gave a lower glucose response than the flour porridge, and there were apparent differences in gastric emptying in both the early and late postprandial phases. The appetite ratings showed similar differences between early- and late-phase behavior. The structure of the oat flakes remained sufficiently intact to delay their gastric emptying, leading to a lower glycemic response, even though initial gastric emptying rates were similar for the flake and flour porridge. This highlights the need to take food structure into account when considering relatively simple physiological measures and offering nutritional guidance. The impact of food structure on glycemic response even in simple foods such as porridge is dependent on both timing of gastric emptying and the composition of what is emptied as well as duodenal starch digestion. Thus structure should be accounted for when considering relatively simple physiological measures and offering nutritional guidance.

Glycaemic, gastrointestinal, hormonal and appetitive responses to pearl millet or oats porridge breakfasts: a randomised, crossover trial in healthy humans

“…An hour later, the liquid phase was no longer visible for both meals, suggesting that gastric sieving promoted the emptying of the liquid component in the stomach contents (51) . These results with flakes are similar to those reported by Mackie et al (60) . Half gastric emptying times were also similar for SOP and PMP.…”

“…The present study assessed the nutritional composition and glycaemic, gastrointestinal, hormonal and appetitive responses of isoenergetic and isovolumetric breakfast porridge meals made from novel pearl millet flakes compared with standard, commercial oat flakes. Oats were chosen as the comparator as these are a common breakfast grain with recognised health-promoting characteristics (25,59,60) . Millet was chosen in this study as the intervention because of potential health benefits indicated by our previous work (42) .…”

“…Pearl millet showed a higher glucose peak value compared with oats, although the difference was modest. Considering that the two meals were well matched for energy and volume and that most of the other responses were very similar, one could speculate that the smaller particle size of PMP flakes compared with SOP flakes may have offered an increased surface area for digestion (28,60) . Other factors, such as total fibre content, were fairly similar; however, the grains contained different types of fibre, potentially explaining the slightly different physiological response (62,63) .…”

Glycaemic, gastrointestinal and appetite responses to breakfast porridges from ancient cereal grains: A MRI pilot study in healthy humans

“…The differences in the glycaemic response seen between these grains could be due to the processing of cereals which alters the digestion of the cereal grains; this is a considered a major determinant of the glycaemic response (Heaton, Marcus, Emmett, & Bolton, 1988;Mackie et al, 2017) and also of the impact on appetite. (Isaksson et al, 2012).…”

Plant Cell Walls: Impact on Nutrient Bioaccessibility and Digestibility

“…More sophisticated techniques allow the study in vivo of digestion and provide some information about the structure of the food within the human GIT. They are, for instance, magnetic resonance imaging (MRI), nasogastric and intestinal intubation to obtain aspirates, and ingestible sensors such as camera capsules [102][103][104][105]. However, some limitations exist with these techniques, including restriction in the number of foods that can be administrated to the volunteers, low resolution (particularly for MRI) and sampling error (appraisal of the entire digesta may not be possible and only particles of a certain size can be recovered by intubation).…”