Fatty acid regio-specificity of triacylglycerol molecules may affect plasma lipid responses to dietary fats—a randomised controlled cross-over trial

BACKGROUND/OBJECTIVES: Hypercholesterolaemic effects of saturated fatty acids (SFA) may be influenced not only by the chain length, but also by their specific location within the triacylglycerol (TAG) molecule. We examined the hypothesis that dietary fats rich in SFA, but containing mostly unsaturated fatty acids in the sn-2 position with most SFA in sn-1 and -3 (palm olein [PO] and cocoa butter [CB]) will have similar serum lipid outcomes to unsaturated olive oil (OO). SUBJECTS/METHODS: Thirty-eight participants (20–40 yr, 18.5– ≤ 27.5 kg/m(2)) completed a 4-week randomised 3 × 3 crossover feeding intervention, preceded by 2-week run-in and separated by 2-week washout periods. Background diet contained 35 percentage of total energy (%E) fat, 18%E protein, 48%E carbohydrates, differing in test fats only (palm olein (PO), CB, OO; 20%E). Total cholesterol (TC)/high density lipoprotein cholesterol (HDL-C) ratio and related variables; TC, HDL-C, low density lipoprotein cholesterol (LDL-C), TAG, apoA1, ApoB, ApoA1 (apolipoprotein A1)/ApoB (apolipoprotein B), lipoprotein (a) (Lp(a)), NEFA, LDL sub-fractions, were assessed pre- and post-intervention. Data were analysed using mixed effects longitudinal models with a P-value < 0.05 considered significant. RESULTS: Changes in plasma fatty acids (P < 0.05) confirmed compliance; C18:1 increased with OO compared to PO and CB; C16:0 decreased with OO and C18:0 increased following CB. No differences were seen for TC/HDL-C (mean [95%CI] change for PO, 0.08[0.00, 0.15] mmol/L; CB, 0.06 [−0.05, 0.16] mmol/L; and OO, −0.01 [−0.15, 0.13] mmol/L; P = 0.53] or any other parameter including LDL sub-fractions. OO decreased IDL-A compared to PO (−2.2 [−4.31, −0.21] mg/dL, P = 0.03). CONCLUSION: In healthy young participants, plasma lipid responses to PO and CB, enriched in SFA but having primarily unsaturated fatty acid in the sn-2 position of TAG, did not differ from OO.