Substitution of dietary monounsaturated fatty acids from olive oil for saturated fatty acids from lard increases LDL apolipoprotein B-100 fractional catabolic rate in subjects with dyslipidemia associated with insulin resistance: a randomized controlled trial

Background The substitution of monounsaturated acids (MUFAs) for saturated fatty acids (SFAs) is recommended for cardiovascular disease prevention but its impact on lipoprotein metabolism in subjects with dyslipidemia associated with insulin resistance (IR) remains largely unknown. Objective This study aimed to evaluate the impact of substituting MUFAs for SFAs on the in vivo kinetics of apolipoprotein (apo)B-containing lipoproteins and on the plasma lipidomic profile in adults with IR-induced dyslipidemia. Design Males and females with dyslipidemia associated with IR (n = 18) were recruited for this crossover double-blind randomized controlled trial. Subjects consumed, in random order, a diet rich in SFAs (SFAs: 13.4%E; MUFAs: 14.4%E) and a diet rich in MUFAs (SFAs: 7.1%E; MUFAs: 20.7%E) in fully controlled feeding conditions for periods of 4 wk each, separated by a 4-wk washout. At the end of each diet, fasting plasma samples were taken together with measurements of the in vivo kinetics of apoB-containing lipoproteins. Results Substituting MUFAs for SFAs had no impact on TRL apoB-48 fractional catabolic rate (FCR) (Δ = –8.9%, P = 0.4) and production rate (PR) (Δ = 0.0%, P = 0.9), although it decreased VLDL apoB-100 pool size (PS) (Δ = -22.5%; P = 0.01). This substitution also reduced LDL-C (Δ = -7.0%; P = 0.01), non-HDL cholesterol (Δ = -2.5%; P = 0.04) and LDL apoB-100 PS (Δ = –6.0%; P = 0.05). These differences were partially attributed to an increase in LDL apoB-100 FCR (Δ = +1.6%; P = 0.05). The MUFA diet showed reduced sphingolipid concentrations and elevated glycerophospholipid levels compared with the SFA diet. Conclusions This study demonstrated that substituting dietary MUFAs for SFAs decreases LDL-C levels and LDL PS by increasing LDL apoB-100 FCR and results in an overall improved plasma lipidomic profile in individuals with IR-induced lipidemia. Trial registration clinicaltrials.gov NCT03872349