Studies have shown that satiety-promoting foods, those that prolong digestion and reduce appetite, may facilitate weight loss by helping to reduce energy intake. Although caloric intake is an important determinant of gastric emptying, studies show that food form can also influence gastric emptying. For example, whole apples produce greater satiety than processed apples, but the underlying mechanisms remain unclear. When attempting to explain how the physical form of food affects satiety, it is important to not only assess changes in gastric emptying but also the changes in the small intestine and colon. These organs provide important feedback mechanisms whereby intestinal signals alter gastric emptying and satiety even after the meal has left the stomach.
A recent study by Robin Spiller (University of Nottingham) and colleagues provides new information regarding the impact of physical forms of food and digestive events in the small intestine and colon using magnetic resonance imaging (MRI) scans. In a 3-way crossover, randomized, controlled trial, 18 healthy adults underwent serial MRI scans on 3 occasions after consuming portions of either whole apples, apple puree, or apple juice. Food portions were of equal caloric equivalency and volume, although fiber content differed. Gastric emptying as well as small bowel and colonic contents were measured at baseline and at 45-minute intervals post-meal ingestion. Fullness and satiety were also assessed at each time point.
Study results published in The Journal of Nutrition showed that the physical form of fruit alters digestive processing and that whole apples were associated with significantly higher satiety scores compared to juice. More specifically, whole apples had significantly slower gastric emptying when compared with puree and liquid forms of apples. Whole apples also increased the water volume in the small and large intestine from 2-4 hours after the meal, long after the stomach was empty. This intestinal phase may be important in reducing total daily intake and avoiding snacking, something which should be tested in future studies. The research team concluded whole fruit is likely to have greater health benefits than processed apples, both on appetite and colonic function. In addition to delayed gastric emptying, whole apples may also enhance satiety and reduce subsequent food consumption, which is key to successful weight reduction. A corresponding editorial by Guido Camps (Wageningen University) provides further insights regarding the puzzle of gastric emptying.
Reference Krishnasamy S, Lomer MCE, Marciani L, Hoad CL, Pritchard SE, Paul J, Gowland PA, Spiller RC. Processing Apples to Puree or Juice Speeds Gastric Emptying and Reduces Postprandial Intestinal Volumes and Satiety in Healthy Adults, The Journal of Nutrition, Volume 150, Issue 11, November 2020, Pages 2890–2899, https://doi.org/10.1093/jn/nxaa191.
Camps G. The Stomach, the Mouth, or the Food? The Puzzle of Gastric Emptying, The Journal of Nutrition, Volume 150, Issue 11, November 2020, Pages 2852–2854, https://doi.org/10.1093/jn/nxaa290.
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