Characterisation with stable isotopes of the presence of a lag phase in the gastric emptying of liquids

Gastric emptying of non-nutrient liquids usually lacks the presence of an initial delay phase (lag phase), and so it has been considered to be monoexponential with an initial rapid phase followed by a slower emptying phase. However a lag phase in the gastric emptying of liquids can be found if there is a high caloric density in the liquid meal. To characterise with stable isotopes the presence of a lag phase in the gastric emptying of non-solid meals. Healthy volunteers ingested a low caloric liquid meal (345 KJ/ 200 mL) (LCLM), a high caloric liquid meal (1135 KJ/180 mL) (HCLM) or a semisolid meal (1403 KJ/500 mL) (SSM). Test meals were labelled with 13C-acetate. Breath samples were collected for 13CO2 measurement and data were fitted to a power exponential function. Non-solid meals can have different behaviour related to the initial emptying. The presence of a lag phase in the gastric emptying of liquids was not masked by the processing of the tracer previous to its detection in breath. While the LCLM and SSM showed a rapid initial emptying phase (no lag phase), the HCLM has an initial slow emptying phase. The slower gastric emptying of the HCLM compared to the SSM was related to the presence of a lag phase in the gastric emptying of the HCLM. The 13C-acetate breath test is very accurate to identify and study the lag phase if present of liquid meals.