Abstract
The effects of positional distribution of triacylglycerol (TAG) fatty acids to TAG structures in chylomicrons and VLDL, and to postprandial lipemia, were studied in 10 healthy premenopausal women using a 6-h oral fat load test and a randomized, double-blind cross-over design. Molecular level information of TAG regioisomerism was obtained with a tandem mass spectrometric method. The positional distribution of fatty acids in chylomicron TAGs was similar to the respective dietary fat; 79% of the analyzed regioisomers in palm oil and 84% of the analyzed regioisomers in transesterified oil were found in chylomicron TAGs 3 h after the oral fat loads. VLDL TAGs were equal after the two fat loads in all but one regioisomer. Similarities in the fatty acid compositions of chylomicron TAGs suggest that palmitic acid was absorbed equally from both test fats. The proportion of palmitoleic acid in the chylomicrons was increased. Fat with palmitic acid predominantly in the sn-1 and sn-3 positions caused a larger incremental area of total TAGs in plasma and reduced plasma insulin values at the beginning of the postprandial response (0–90 min) compared with fat with palmitic acid randomly distributed. The relationship between TAG molecular structures in dietary fats and in lipoproteins provides new means for understanding the effects of fatty acid positonal distribution on human lipid metabolism.—Yli-Jokipii, K., H. Kallio, U. Schwab, H. Mykkänen, J-P. Kurvinen, M. J. Savolainen, and R. Tahvonen. Effects of palm oil and transesterified palm oil on chylomicron and VLDL triacylglycerol structures and postprandial lipid response. J. Lipid Res. 2001. 42: 1618–1625.
Highlights
The effects of positional distribution of triacylglycerol (TAG) fatty acids to TAG structures in chylomicrons and VLDL, and to postprandial lipemia, were studied in 10 healthy premenopausal women using a 6-h oral fat load test and a randomized, double-blind cross-over design
The fatty acid composition of a diet has an effect on the fatty acid composition of VLDL TAGs and possibly on the positional distribution of fatty acids in VLDL TAGs [14]
The proportions of major fatty acids in chylomicron TAGs were similar after the two meals and during the course of postprandial lipemia (Table 3)
Summary
The study had a randomized double-blind cross-over design. Postprandial responses to two meals containing either palm oil or transesterified palm oil were measured over 6 h on two occasions 4 weeks apart. The energy percentages from fat, protein, and carbohydrate calculated from the 4-day food records with Micronutrica software (Version 2.5) [18] did not differ between the treatments, but the percentage of total energy from saturated fat was greater before the test with palm oil than before the test with transesterified palm oil (P ϭ 0.031). The different positional distributions influenced the melting qualities of the fats, because at 20ЊC transesterified palm oil contained 17.8% solid fat but palm oil was totally melted, as measured by pulse nuclear magnetic resonance (Bruker Minispec NMS-100, Germany). Both fats were liquid at body temperature. Fat from the cheese accounted for 1 –2% of total fat
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