Oral administration of lipid oil-in-water emulsions performed with synthetic or protein-type emulsifiers differentially affects post-prandial triacylglycerolemia in rats

In this study, we compared the impact of administration of size-calibrated lipid emulsions prepared with either synthetic or natural emulsifiers on the post-absorptive plasma triacylglycerol responses in rats. We did this using four types of size-calibrated (10 μm diameter) and metastable (3 days) emulsions with 20% of an oleic acid-rich sunflower oil and 1% of either synthetic emulsifiers (Tween 80 or sodium 2-stearoyl-lactylate) or two proteins (β-lactoglobulin or sodium caseinate). An oral fat tolerance test was performed in fasted rats by oral administration of each of these formulations in continuous or emulsified forms. Kinetic parameters (AUC 0-inf. , AUC 0-6h , C max , T max , and T 1/2 ) for the description of the plasma triacylglycerol responses were calculated. AUC 0-6h and AUC 0-inf. calculated for the protein groups were significantly lower than those of the control and the synthetic groups. These lower values were associated with significant decreases in the C max , exacerbated by the emulsion form and with marked decreases in the T max as compared to the control group. T 1/2 values were differentially affected by the lipid administration forms and by the nature of the emulsifiers. As compared with the control group, T 1/2 was largely increased in the sodium stearoyl-2-lactylate group, but on the contrary, largely lowered in the casein group. We concluded that the use of proteins as natural emulsifiers in lipid emulsions decreased the magnitude of post-prandial triacylglycerolemia for the same amount of ingested lipids, when the emulsion size is controlled for. Proteins could be a promising alternative to the widespread use of synthetic emulsifiers in the food industry.