Effects of Diets Enriched with Conventional or High-Oleic Canola Oils on Vascular Endothelial Function: A Sub-Study of the Canola Oil Multi-Centre Intervention Trial 2 (COMIT-2), a Randomized Crossover Controlled Feeding Study.

Partial replacement of saturated fatty acids (SFA) with unsaturated fatty acids is recommended to reduce cardiovascular disease (CVD) risk. Monounsaturated fatty acids (MUFA), including oleic acid, are associated with lower CVD risk. Measurement of flow-mediated dilation of the brachial artery (FMD) is the gold standard for measuring endothelial function and predicts CVD risk. This study examined the effect of partially replacing SFA with MUFA from conventional canola oil and high-oleic acid canola oil on FMD. Participants (n = 31) with an elevated waist circumference plus ≥1 additional metabolic syndrome criterion completed FMD measures as part of the Canola Oil Multi-Centre Intervention Trial 2 (COMIT-2), a multi-center, double-blind, three-period crossover, controlled feeding randomized trial. Diet periods were 6 weeks, separated by ≥4-week washouts. Experimental diets were provided during all feeding periods. Diets only differed by the fatty acid profile of the oils: canola oil (CO; 17.5% energy from MUFA, 9.2% polyunsaturated fatty acids (PUFA), 6.6% SFA), high-oleic acid canola oil (HOCO; 19.1% MUFA, 7.0% PUFA, 6.4% SFA), and a control oil blend (CON; 11% MUFA, 10% PUFA, 12% SFA). Multilevel models were used to examine the effect of the diets on FMD. No significant between-diet differences were observed for average brachial artery diameter (CO: 6.70 ± 0.15 mm, HOCO: 6.57 ± 0.15 mm, CON: 6.73 ± 0.14 mm; p = 0.72), peak brachial artery diameter (CO: 7.11 ± 0.15 mm, HOCO: 7.02 ± 0.15 mm, CON: 6.41 ± 0.48 mm; p = 0.80), or FMD (CO: 6.32 ± 0.51%, HOCO: 6.96 ± 0.49%, CON: 6.41 ± 0.48%; p = 0.81). Partial replacement of SFA with MUFA from CO and HOCO had no effect on FMD in participants with or at risk of metabolic syndrome.

Diets Enriched with Conventional or High-Oleic Acid Canola Oils Lower Atherogenic Lipids and Lipoproteins Compared to a Diet with a Western Fatty Acid Profile in Adults with Central Adiposity.

BACKGROUND: Novel oils high in monounsaturated fatty acids (MUFAs) and low in saturated fatty acids (SFAs) are an alternative to partially hydrogenated oils high in trans-unsaturated fatty acids. There is widespread use of high-MUFA oils across the food industry; however, limited knowledge of their cardiovascular impact exists. OBJECTIVES: We investigated the effects of diets containing canola oil, high-oleic acid canola oil (HOCO), and a control oil blend (diet formulated to emulate a Western fat profile) on lipids, lipoproteins, and apolipoproteins (apos), as secondary outcomes of the trial. METHODS: In a multi-center, double-blind, randomized, 3-period crossover, controlled feeding trial, men (n = 44) and women (n = 75) with a mean age of 44 y, mean body mass index (BMI; in kg/m2) of 31.7, and an increased waist circumference plus ≥1 metabolic syndrome criteria consumed prepared, weight-maintenance diets containing canola oil [17.5% MUFAs, 9.2% polyunsaturated fatty acids (PUFAs), 6.6% SFAs], HOCO (19.1% MUFAs, 7.0% PUFAs, 6.4% SFAs), or control oil (10.5% MUFAs, 10.0% PUFAs, 12.3% SFAs) for 6 wk with ≥4-wk washouts. Fasting serum lipids were assessed at baseline and 6 wk. Diet effects were examined using a repeated measures mixed model. RESULTS: Compared with the control, canola and HOCO diets resulted in lower endpoint total cholesterol (TC; -4.2% and -3.4%; P < 0.0001), LDL cholesterol (-6.6% and -5.6%; P < 0.0001), apoB (-3.7% and -3.4%; P = 0.002), and non-HDL cholesterol (-4.5% and -4.0%; P = 0.001), with no differences between canola diets. The TC:HDL cholesterol and apoB:apoA1 ratios were lower after the HOCO diet than after the control diet (-3.7% and -3.4%, respectively). There were no diet effects on triglyceride, HDL cholesterol, or apoA1 concentrations. CONCLUSIONS: HOCO, with increased MUFAs at the expense of decreased PUFAs, elicited beneficial effects on lipids and lipoproteins comparable to conventional canola oil and consistent with reduced cardiovascular disease risk in adults with central adiposity. This trial was registered at www.clinicaltrials.gov as NCT02029833.

Canola oil rich in oleic acid improves diastolic heart function in diet-induced obese rats.

Obesity is a leading cause of cardiovascular disease. It directly affects heart structure and function and contributes to heart failure. Diet is a major factor involved in the development of obesity along with genetic factors. We examined the effects of monounsaturated and polyunsaturated fatty acid-rich oils on cardiac structure and function in the diet-induced rodent model of obesity (DIO). Obese prone (OP) rats were fed a high-fat diet (HF; 55% of kcal) for 12 weeks; Sprague-Dawley rats fed commercial chow served as control. Echocardiography was performed to assess the cardiac structure and function in all rats at 12 weeks. OP rats fed the HF diet showed significant impairment in diastolic function compared to control rats. The HF diet containing high oleic canola oil significantly improved diastolic function of OP rats compared to the HF diet with lard. In conclusion, canola oil rich in oleic acid, when incorporated into an HF diet, prevents the development of diastolic dysfunction in DIO rats.