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Abstract
Objective: Saturated fats increase total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C) and are linked to coronary artery disease risk. The effect of variance in chain length of saturated fatty acids (SFA) on coronary artery disease in human postprandial lipemia is not well elucidated.
Methods: A total of 20 healthy volunteers were challenged with 3 test meals, similar in fat content (∼31% en) but varying in saturated SFA content and polyunsaturated/saturated fatty acid ratios (P/S). The 3 meals were lauric + myristic acid-rich (LM), P/S 0.19; palmitic acid-rich (POL), P/S 0.31; and stearic acid-rich (STE), P/S 0.22. Blood was sampled at fasted baseline and 2, 4, 5, 6, and 8 hours. Plasma lipids (triacylglycerol [TAG]) and lipoproteins (TC, LDL-C, high density lipoprotein-cholesterol [HDL-C]) were evaluated.
Results: Varying SFA in the test meal significantly impacted postprandial TAG response (p < 0.05). Plasma TAG peaked at 5 hours for STE, 4 hours for POL, and 2 hours for LM test meals. Area-under-the-curve (AUC) for plasma TAG was increased significantly after STE treatment (STE > LM by 32.2%, p = 0.003; STE > POL by 27.9%, p = 0.023) but was not significantly different between POL and LM (POL > LM by 6.0%, p > 0.05). At 2 hours, plasma HDL-C increased significantly after the LM and POL test meals compared with STE (p < 0.05). In comparison to the STE test meal, HDL-C AUC was elevated 14.0% (p = 0.005) and 7.6% (p = 0.023) by the LM and POL test meals, respectively. The TC response was also increased significantly by LM compared with both POL and STE test meals (p < 0.05).
Conclusions: Chain length of saturates clearly mediated postmeal plasma TAG and HDL-C changes.
ACKNOWLEDGMENTS
The contribution of each author is as follows: T.K., an accredited practicing dietitian, was responsible for data acquisition and drafting of this manuscript; C.H.T. was a graduate student participating in the implementation of the study; K.C. was responsible for statistical analyses and interpretation of data; K.S. made substantial contributions to conception and design of the study and finalization of the manuscript. None of the authors have a conflict of interest to declare. This research protocol was approved by the Ethical Approval Committee of the National University of Malaysia with the registration number FF-165-2007.
Fig. 1. (a) Plasma TAG (mean ± SEM, n = 20) concentrations over 8 hours in response to test meals containing POL, LM, or STE oil type. Repeated measures MANOVA analyzed for time × test meal interactions was significant (p = 0.002). The lipemic trend generated by the C18:0-rich STE meal was greater than that of the C16:0-rich POL (p = 0.023) or LM (p = 0.003) test meals. (b) Univariate analyses on AUC for plasma TAG was significantly higher for the STE test meal (p = 0.016) compared with the LM (>32.2%) and POL (>27.9%) test meals, whereas the difference between the POL and LM test meals (6.0%) was not significant. POL = palm olein only (♦), LM = lauric + myristic acid-rich oil obtained from blending coconut and corn oils (▪), STE = stearic acid-rich oil obtained by blending cocoa butter with corn oil (▴).
Fig. 2. (a) Plasma TC response (mean ± SEM, n = 20) over 8 hours following a standardized fat load with the POL, LM, or STE test meals. Repeated measures MANOVA analysis for time × test meal interactions was not significant (p < 0.05). An effect of time was significant from 5 to 8 hours (p = 0.026) with significantly greater plasma TC response generated by the LM compared with the POL and STE test meals (p = 0.033). (b) Univariate analyses for AUC of plasma TC was not significantly different. POL = palm olein only (♦), LM = lauric + myristic acid-rich oil obtained from blending coconut and corn oils (▪), STE = stearic acid-rich oil obtained by blending cocoa butter with corn oil (▴).
Fig. 3. (a) Plasma HDL-C (mean ± SEM, n = 20) concentrations over 8 hours in response to test meals containing POL, LM, or STE test fats. Repeated measures MANOVA analyzed for time × test meal interactions was significant (p = 0.003) and comparisons between meals was significant between the STE and POL (p = 0.023) meals and the STE and LM (p = 0.005) meals but not between the LM and POL meals. (b) AUC for plasma HDL-C (means ± SEM, n = 20) as analyzed by univariate analysis was not significantly different from baseline except at 2 hours (p = 0.055), for which the STE meal was 14.0% greater compared with the LM (p = 0.005) and 7.6% greater compared with the POL (p = 0.023) meals. POL = palm olein only (♦), LM = lauric + myristic acid-rich oil obtained from blending coconut and corn oils (▪), STE = stearic acid-rich oil obtained by blending cocoa butter with corn oil (▴).
Fig. 4. (a) Plasma LDL-C (mean ± SEM, n = 20) concentrations over 8 hours in response to test meals containing POL, LM, or STE test fats. Repeated measures MANOVA analyzed for time × test meal interactions were not significant (p > 0.05). (b) No significant difference for plasma LDL-C AUC (mean ± SEM, n = 20) was noted between test meals (p > 0.05). POL = palm olein only (♦), LM = lauric + myristic acid-rich oil obtained from blending coconut and corn oils (▪), STE = stearic acid-rich oil obtained by blending cocoa butter with corn oil (▴).
Fig. 5. Fatty acid composition (FAC) of triacylglycerol (TAG) in triacylglycerol-rich lipoproteins (TRL) (mean % ± SEM, n = 20) in response to test meals containing POL, LM, or STE test fats. Statistical analyses were corrected for baseline values and significance reported at p < 0.05 for time × meal interactions. (a) Percentage C12:0+C14:0 increased significantly after LM meal compared with the POL and STE meals (p < 0.05), whereas comparisons between POL and STE were not significantly different (p > 0.05). (b) Percentage C16:0 increased significantly after the POL meal compared with the LM and STE meals (Fig. 5. Continued.) (p < 0.05), whereas comparisons between LM and STE were not significantly different (p > 0.05). (c) Percentage C18:0 increased significantly after the STE meal compared with the POL and LM meals (p < 0.05), whereas comparisons between POL and LM were not significantly different (p > 0.05). (d) Percentage C18:1 increased significantly after the POL meal compared with the STE and LM meals (p < 0.05), whereas comparisons between STE and LM were not significantly different (p > 0.05). POL = palm olein only (♦), LM = lauric + myristic acid-rich oil obtained from blending coconut and corn oils (▪), STE = stearic acid-rich oil obtained by blending cocoa butter with corn oil (▴).
Fig. 6. Fatty acid composition (FAC) of plasma cholesteryl esters (CE) (mean % ± SEM, n = 20) in response to test meals containing POL, LM, or STE test fats. Statistical analyses were corrected for baseline values and significance reported at p < 0.05 for time × test meal interactions. (a) Percentage C12:0+C14:0 increased significantly after the LM meal compared with the POL and STE meals (p < 0.05), whereas comparisons between POL and STE were not significantly different (p > 0.05). (b) Percentage C16:0 increased significantly after the POL meal compared with the LM and STE meals (p < 0.05), whereas comparisons between LM and STE were not significantly (Fig. 6. Continued.) different (p > 0.05). (c) Percentage C18:0 increased significantly after the STE meal compared with the POL and LM meals (p < 0.05), whereas comparisons between POL and LM were not significantly different (p > 0.05). (d) Percentage C18:1 was significantly greater after the POL and STE meals compared with the LM meal (p < 0.05), whereas comparisons between POL and STE were not significantly different (p > 0.05). POL = palm olein only (♦), LM = lauric + myristic acid-rich oil obtained from blending coconut and corn oils (▪), STE = stearic acid-rich oil obtained by blending cocoa butter with corn oil (▴).
Table 1. Fatty Acid Composition of the Test Fats and Test Meals*
Notes
Supported by a grant from the Ministry of Science, Technology and Innovations, Kuala Lumpur, Malaysia (E-Science Grant No. 06-01-02-SF0313).
None of the authors have a conflict of interest to declare.