A tale of gastric layering and sieving: Gastric emptying of a liquid meal with water blended in or consumed separately.
BACKGROUND
The process of gastric emptying determines how fast gastric content is delivered to the small intestine. It has been shown that solids empty slower than liquids and that a blended soup empties slower than the same soup as broth and chunks, due to the liquid fraction emptying more quickly. This process of 'gastric sieving' has not been investigated for liquid foods.


OBJECTIVE
To determine whether gastric sieving of water can also occur for liquid foods.


METHODS
Two groups of men participated in a parallel design (n=15, age 22.6±2.4y, BMI 22.6±1.8kg/m2, and n=19, age 22.2±2.5y, BMI 21.8±1.5kg/m2) and consumed an isocaloric shake (2093kJ, CARBOHYDRATES: 71g, FAT: 18g, PROTEIN: 34g), either in a 500-mL version (MIXED) or as a 150-mL shake followed by 350mL water (SEPARATE). Participants provided appetite ratings and were scanned using MRI to determine gastric emptying rate and volume at three time-points within 35min post ingestion.


RESULTS
Gastric emptying the percentage emptied in 35min was significantly smaller for MIXED (29±19%) than for SEPARATE (57±11%, p<0.001).


CONCLUSIONS
In the present study we show that gastric sieving can occur for liquid foods; water is able to drain from the stomach while a layer of nutrient rich liquid is retained. In indirect gastric emptying measurements, the behavior of labelling agents may be affected by the layering and confound emptying measurements.
Department of Human Nutrition, Wageningen University & Research, Wageningen, The Netherlands. Electronic address: guido.camps@wur.nl.
Guido
G
Camps
Department of Human Nutrition, Wageningen University & Research, Wageningen, The Netherlands.
Monica
M
Mars
Department of Human Nutrition, Wageningen University & Research, Wageningen, The Netherlands.
Cees
C
de Graaf
Department of Human Nutrition, Wageningen University & Research, Wageningen, The Netherlands; Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
Paul A M
PAM
Smeets
D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D005260:Female; D005746:Gastric Emptying / Q000502:physiology*; D005766:Gastrointestinal Contents; D006801:Humans; D006815:Hunger / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D062407:Meals; D012527:Satiation / Q000502:physiology; D013270:Stomach / Q000737:chemistry / Q000000981:diagnostic imaging*; D014867:Water / Q000502:physiology*; D055815:Young Adult
D014867:Water
Gastric emptying; Liquid meal; MRI; Water