Acute Effects of Sn-1 and Sn-3 Palmitic Acid-Rich or Stearic Acid-Rich Fats on Postprandial Markers of Cardiovascular Risk, Insulinemic Response, and Gut Hormones in Human Volunteers

Abstract

Dietary fat when consumed reduces hunger and impairs food intake by eliciting satiety signals and these signals are evoked by entry of triacylglycerol after hydrolization to fatty acids into the small intestine. 1,3-dipalmitoyl-2-oleoyglycerol (POP-), 1,3-distearoyl-2-oleoylglycerol (SOS-) and 1,2,3-triolein (OOO-) type of fats have different melting characteristics that may affect postprandial blood lipids, gut hormone concentrations, insulinemic response and selected cardiovascular disease markers in human volunteers. The main objective of this study is to compare the effects of edible fats with either palmitic acid (16:0) (palm mid-fraction) or stearic acid (18:0) (shea stearin) predominantly at the sn-1 and sn-3 positions on postprandial lipemia and gut hormone concentrations.

A randomized, double-blind crossover (3 × 3 arms) orthogonal Latin-square design was used on 36 healthy adults (18 males, 18 females; mean age = 23 years). Each subject received 3 different test muffins (each containing 53 g of test fat) in random order separated by 2 weeks over a 6-week period. The test fats of different melting points were palm mid- fraction (PMF; POP-rich), shea stearin (SS; SOS-rich) and high- oleic sunflower oil (HOSF; OOO-rich) During a postprandial test, each subject was provided with a test muffin plus milkshake (total 3.67 MJ or 876 kcal) in the morning and blood samples were collected at half-hourly intervals until 4.0 hours. No significant difference (p>0.05) was observed between the 3 test meals for postprandial responses in plasma TC, Lp(a), apo(B), NEFA, GLP-1, PYY, ghrelin, VAS, PAI-1, IL-6, TNF-α, glucose, insulin and satiety (VAS scores). Plasma TAG peaked at about 4 hours; levels in the PMF- and HOSF- subjects were significantly higher (p<0.05) compared with SS-subjects after 90 minutes. PMF and HOSF exerted a higher postprandial GIP response (p<0.05) as compared to SS. Plasma C-peptide levels, as a measure of insulinemic response, rose sharply 5.5- folds in all groups, peaking after 90 minutes; levels in the SS group declined at a faster rate (p<0.05) than in the PMF- and HOSF- groups.

The POP- and OOO- fats induced similar effects on all the biochemical/physiological outcome measures investigated. In contrast, the SOS- type fat (shea stearin) induced a slower rise (p<0.05) in postprandial TAG and GIP levels and a faster return of plasma C-peptide levels to baseline.