Submitted to: Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/23/2013
Publication Date: 6/7/2013
Citation: Richard, C., Couture, P., Desroches, S., Lichtenstein, A., Lamarche, B. 2013. Effect of an isoenergetic traditional Mediterranean diet on apolipoprotein A-I kinetic in men with metabolic syndrome. Nutrition. 12:76. Interpretive Summary: The dietary pattern referred to as the Mediterranean diet (MedDiet) has been associated with positive health outcomes. One factor that may contribute the beneficial effect of this dietary pattern is the way high-density lipoprotein-cholesterol (HDL-C), the ‘good’ cholesterol, is metabolized in the body. Or it may also be due to changes in body weight that frequently accompany a shift from a Western type diet to MedDiet. The objective of this study was to investigate the effect of the MedDiet in the absence of changes in body weight on apolipoprotein (apo) A-I metabolism. Apo A-I is the major protein in HDL. All participants in this study were men who were diagnosed with metabolic syndrome, defined as having three or more of the following; high triglyceride concentrations, low HDL-C concentrations, high waist circumference, high blood pressure and/or high fasting glucose concentrations. Participants were first provided with a Western-type diet for 5 weeks in amounts to minimize changes in current body weight, and then a MedDiet type at the same energy (calorie) level for an additional 5 weeks. During the last week of each diet period participants received a single bolus dose of a harmless radioactive supplement to track the metabolism of apoA-I. The response of HDL-C concentrations to the MedDiet was mixed compared with the period when the participants were given the Western type diet. Blood concentrations of apoA-I and pool size were significantly lower after the MedDiet period. ApoA-I production rate tended to be reduced These data indicate that compared to a Western type dietary pattern, a MedDiet produces a variable response in HDL-C concentrations among study subjects. Further they show that when changes in HDL-C concentrations occur, they result from changes in production rather than clearance from plasma.
Technical Abstract: The impact of the Mediterranean diet (MedDiet) on high-density lipoprotein (HDL) kinetics has not been studied to date. The objective of this study was therefore to investigate the effect of the MedDiet in the absence of changes in body weight on apolipoprotein (apo) A-I kinetic in men with metabolic syndrome (MetS). Twenty-six men with MetS (NCEP-ATP III) were recruited from the general community. In this fixed sequence study, participants’ diet was first standardized to a control diet reflecting current averages in macronutrient intake in North American men, with all foods and beverages provided under isoenergetic conditions for 5 weeks. Participants were then fed an isoenergetic MedDiet over a subsequent period of 5 weeks to maintain their weight constant. During the last week of each diet, participants received a single bolus dose of [5,5,52H3] L-leucine and fasting blood samples were collected at predetermined time points. ApoA-I kinetic was determined by multicompartmental modeling using isotopic enrichment data over time. Data were analyses using MIXED models. The response of HDL-cholesterol (C) to MedDiet was heterogeneous, such that there was no mean change compared with the control diet. Plasma apoA-I concentration (-3.9%) and pool size (-5.3%, both P'<'0.05) were significantly lower after MedDiet and apoA-I production rate tended to be reduced (-5.7%, P'='0.07) with no change in apoA-I fractional catabolic rate (FCR, -1.6%, P'='0.64). Participants among whom HDL-C concentrations were increased with MedDiet (responders: mean change in HDL-C: +9.9'+/-'3.2%, N'='11) showed significantly greater reductions in apoA-I FCR and in apoB and very-low-density lipoprotein-triglycerides (VLDL-TG) concentrations (all P'<'0.04) than those among whom HDL-C levels were reduced after the MedDiet (non-responders: mean change in HDL-C: -12.0'+/-'3.9%, N'='8). Correlation analysis revealed that only variations in apoA-I FCR (r'='-0.48, P'='0.01) and in plasma VLDL-TG (r'='-0.45, P'='0.03) concentrations were correlated with the individual HDL-C response to the MedDiet. Data from this controlled feeding study suggest that the heterogeneous response of HDL-C to MedDiet, in the absence of important weight loss, is primarily related to individual variations in apoA-I FCR and in plasma VLDL-TG concentrations.