Ultrasonography assessment of gastric emptying for different emulsion microstructures was superior to acetaminophen marker method

Gastric emptying (GE) influences postprandial metabolism, including satiety and is partially mediated by food structure. Tools for routine GE assessment and suitable for a range of food structures in metabolic studies are warranted. This study compared GE results from the acetaminophen absorption (plasma concentration) versus ultrasonography (US, gastric antrum area) methods when 15 healthy men consumed four oil-in-water emulsions differing in lipid physical state and emulsifier acid stability, meaning gastric phase behaviours differed. Plasma acetaminophen was only correlated with antrum measurements for the intragastrically stable emulsion with liquid lipid droplets (P = 0.041, r = −0.69). The US results support the role of colloidal stability in delaying GE and the images showed different gastric phase behaviours. In contrast, acetaminophen solubility confounded the results when the emulsions were susceptible to acidic flocculation. US antrum measurements (but not the acetaminophen results) were also correlated with participant subjective satiety (P < 0.0001), supporting the close mediation of satiety perception by antral distention. Overall, US was superior to the acetaminophen method for assessing GE. It was easily implemented, provided visual insights into gastric phase behaviour, and predicted subjective satiety responses, allowing us to relate food structure and changes therein during digestion to metabolic response.