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There is considerable interest in manipulating the behavior of dietary emulsions in the human stomach as a means of altering satiating properties of fatty foods. However assessing this using intubation markedly disturbs normal gastric motility so a non-invasive imaging approach has a strong rationale. Two 20% sunflower oil-in-water fat emulsions test meals with different droplet sizes (termed Fine and Coarse) and intragastric behaviors were used to demonstrate, for the first time, the feasibility of carrying out magnetic resonance spectroscopy (MRS) measurements of fat emulsions fat fraction, in vivo, in the gastric lumen of six healthy volunteers. Magnetic resonance imaging (MRI) confirmed that as expected the fine emulsion remained mostly homogeneously distributed inside the stomach over the course of 3 h but the Coarse quickly creamed showing an upper layer much richer in fat. The MRS measurements showed that the Coarse emulsion had an upper layer of high lipid/water ratio compared to the lower layer. The fine emulsion fat fraction values remained stable throughout the study with no difference between upper and lower layers. It is therefore possible to quantify in vivo, in the gastric lumen, the intragastric fat fraction of oil-in-water fat emulsions using non invasive MRS techniques. Practical applications: This study shows that it is possible to quantify in vivo, in the gastric lumen, the intragastric fat fraction of oil-in-water fat emulsions using non invasive magnetic resonance spectroscopy techniques. These measurements can help improve understanding of intragastric distribution of fat, its relation to satiety, can improve the relevance of in vitro/in vivo models of fat digestion, and will ultimately aid the design of foods with desired health promoting characteristics and check their performance in vivo. Two 20% sunflower oil-in-water fat emulsions test meals with different droplet sizes and intragastric behaviours are used to demonstrate, for the first time, the feasibility of carrying out magnetic resonance spectroscopy (MRS) measurements of fat emulsions fat fraction, in vivo, in the gastric lumen of six healthy volunteers.

Background: Intragastric creaming and droplet size of fat emulsions may affect intragastric behavior and gastrointestinal and satiety responses. Objectives: We tested the hypotheses that gastrointestinal physiologic responses and satiety will be increased by an increase in intragastric stability and by a decrease in fat droplet size of a fat emulsion. Methods: This was a double-blind, randomized crossover study in 11 healthy persons [8 men and 3 women, aged 24 ± 1 y; body mass index (in kg/m2): 24.4 ± 0.9] who consumed meals containing 300-g 20% oil and water emulsion (2220 kJ) with 1) larger, 6-μm mean droplet size (Coarse treatment) expected to cream in the stomach; 2) larger, 6-μm mean droplet size with 0.5% locust bean gum (LBG; Coarse+LBG treatment) to prevent creaming; or 3) smaller, 0.4-μm mean droplet size with LBG (Fine+LBG treatment). The participants were imaged hourly by using MRI and food intake was assessed by using a meal that participants consumed ad libitum. Results: The Coarse+LBG treatment (preventing creaming in the stomach) slowed gastric emptying, resulting in 12% higher gastric volume over time (P < 0.001), increased small bowel water content (SBWC) by 11% (P < 0.01), slowed appearance of the 13C label in the breath by 17% (P < 0.01), and reduced food intake by 9% (P < 0.05) compared with the Coarse treatment. The Fine+LBG treatment (smaller droplet size) slowed gastric emptying, resulting in 18% higher gastric volume (P < 0.001), increased SBWC content by 15% (P < 0.01), and significantly reduced food intake by 11% (P < 0.05, equivalent to an average of 411 kJ less energy consumed) compared with the Coarse+LBG treatment. These high-fat meals stimulated substantial increases in SBWC, which increased to a peak at 4 h at 568 mL (range: 150–854 mL; P < 0.01) for the Fine+LBG treatment. Conclusion: Manipulating intragastric stability and fat emulsion droplet size can influence human gastrointestinal physiology and food intake.