Emulsion Droplet Crystallinity Attenuates Postprandial Plasma Triacylglycerol Responses in Healthy Men: A Randomized Double-Blind Crossover Acute Meal Study

Abstract

Background: The presence of triacylglycerol (TAG) cystallinity is assumed to influence digestibility and postprandial lipemia (PPL), although studies to date are limited.

Objective: This study aimed to investigate whether the presence of solid fat compared with undercooled liquid oil, specifically, plays a role in determining PPL by comparing emulsion droplets differing only in terms of physical state.

Methods: Ten percent palm stearin and 0.4% sorbitan monostearate emulsions were tempered to contain identically sized, charged, and shaped (spherical) undercooled liquid (LE) compared with partially crystalline solid (SE; mean ± SEM: 33.2% ± 0.03% solid fat at 37°C) droplets. Fifteen healthy fasting adult men (mean ± SD age: 27.5 ± 5.7 y; BMI: 24.1 ± 2.5 kg/m2) consumed 500 mL of each emulsion on separate occasions and plasma TAG concentrations, particle size of the plasma chylomicron-rich fraction (CMRF), and fatty acid (FA) composition of the CMRF-TAG were serially determined in a 6-h postprandial randomized double-blind crossover acute meal study. Changes from baseline values were analyzed by repeated-measures ANOVA.

Results: An earlier (2 compared with 3 h, P < 0.05) significant rise, a 39.9% higher mean postprandial TAG change from baseline (P = 0.08), and higher peak concentration (mean ± SEM: 1.47 ± 0.19 compared with 1.20 ± 0.15 mmol/L, P = 0.04) and iAUC (1.95 ± 0.39 compared with 1.45 ± 0.31 mmol/L × h, P = 0.03) values were observed for LE compared with SE. The compositions of the CMRF-TAG FAs shifted toward those of the ingested palm stearin by 4 h but did not differ between SE and LE (P = 0.90). Nor were there differences in postprandial changes in CMRF particle size (P = 0.79) or nonesterified FAs (P = 0.72) based on lipid physical state.

Conclusions: Despite their identical compositions and colloidal properties, differences in lipid absorption were observed between SE and LE in healthy adult men. This is direct evidence that TAG physical state contributes to PPL, with the presence of solid fat having an attenuating influence.This trial was registered at clinicaltrials.gov as NCT03515590.

Keywords: acute meal study; chylomicron-rich fraction; emulsions; healthy men; plasma triacylglycerol response; postprandial lipemia; solid fat content.