Palmitic acid in the sn-2 position of dietary triacylglycerols does not affect insulin secretion or glucose homeostasis in healthy men and women

BACKGROUND/OBJECTIVES: Dietary triacylglycerols containing palmitic acid in the sn-2 position might impair insulin release and increase plasma glucose.

SUBJECTS/METHODS: We used a cross-over designed feeding trial in 53 healthy Asian men and women (20-50 years) to test this hypothesis by exchanging 20% energy of palm olein (PO; control) with randomly interesterified PO (IPO) or high oleic acid sunflower oil (HOS). After a 2-week run-in period on PO, participants were fed PO, IPO and HOS for 6 week consecutively in randomly allocated sequences. Fasting (midpoint and endpoint) and postprandial blood at the endpoint following a test meal (3.54 MJ, 14 g protein, 85 g carbohydrate and 50 g fat as PO) were collected for the measurement of C-peptide, insulin, glucose, plasma glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1, lipids and apolipoproteins; pre-specified primary and secondary outcomes were postprandial changes in C-peptide and plasma glucose.

RESULTS: Low density lipoprotein cholesterol was 0.3 mmol/l (95% confidence interval (95% CI)) 0.1, 0.5; P <0.001) lower on HOS than on PO or IPO as predicted, indicating good compliance to the dietary intervention. There were no significant differences (P=0.58) between diets among the 10 male and 31 female completers in the incremental area under the curve (0-2 h) for C-peptide in nmol.120 min/l: GM (95% CI) were PO 220 (196, 245), IPO 212 (190, 235) and HOS 224 (204, 244). Plasma glucose was 8% lower at 2h on IPO vs PO and HOS (both P <0.05).

CONCLUSION: Palmitic acid in the sn-2 position does not adversely impair insulin secretion and glucose homeostasis.