Effect of Lowering the Glycemic Load With Canola Oil on Glycemic Control and Cardiovascular Risk Factors: A Randomized Controlled Trial

Abstract

OBJECTIVEDespite their independent cardiovascular disease (CVD) advantages, effects of a-linolenic acid (ALA), monounsaturated fatty acid (MUFA), and low-glycemicload (GL) diets have not been assessed in combination. We therefore determined the combined effect of ALA, MUFA, and low GL on glycemic control and CVD risk factors in type 2 diabetes. RESEARCH DESIGN AND METHODSThe study was a parallel design, randomized trial wherein each 3-month treatment was conducted in a Canadian academic center between March 2011 and September 2012 and involved 141 participants with type 2 diabetes (HbA 1c 6.5%-8.5% [48-69 mmol/mol]) treated with oral antihyperglycemic agents. Participants were provided with dietary advice on either a low-GL diet with ALA and MUFA given as a canola oil-enriched bread supplement (31 g canola oil per 2,000 kcal) (test) or a whole-grain diet with a whole-wheat bread supplement (control). The primary outcome was HbA 1c change. Secondary outcomes included calculated Framingham CVD risk score and reactive hyperemia index (RHI) ratio. RESULTSSeventy-nine percent of the test group and 90% of the control group completed the trial. The test diet reduction in HbA 1c units of 20.47% (25.15 mmol/mol) (95% CI 20.54% to 20.40% [25.92 to 24.38 mmol/mol]) was greater than that for the control diet (20.31% [23.44 mmol/mol] [95% CI 20.38% to 20.25% (24.17 to 22.71 mmol/mol)], P = 0.002), with the greatest benefit observed in those with higher systolic blood pressure (SBP). Greater reductions were seen in CVD risk score for the test diet, whereas the RHI ratio increased for the control diet. CONCLUSIONSA canola oil-enriched low-GL diet improved glycemic control in type 2 diabetes, particularly in participants with raised SBP, whereas whole grains improved vascular reactivity.

Extra-Virgin Olive Oil Reduces Glycemic Response to a High–Glycemic Index Meal in Patients With Type 1 Diabetes: A Randomized Controlled Trial

“…This is also supported by the favorable glycemic effects shown for the MUFA-rich canola oil (26). The influence of the degree of fat unsaturation on postprandial glucose and insulin responses has been evaluated in healthy people (16,27) and patients with type 2 diabetes (17) with no univocal results, with the inconsistencies mainly related to differences in the experimental design.…”

Food Consumption and its Impact on Cardiovascular Disease: Importance of Solutions Focused on the Globalized Food System

“…Replacing saturated fat with monounsaturated or polyunsaturated fat reduces low-density lipoprotein cholesterol (LDL-C) and preserves HDL-C (109). Further, canola oil, as part of a low-glycemic index diet, improves glycemic control and blood lipids in type 2 diabetes (138). Trans -fatty acids increase CHD risk compared with other macronutrients, with strong evidence of adverse effects of small amounts of trans -fats on lipids (109,139) and CVD risk (140,141).…”

Main Properties of Canola Oil Components: A Descriptive Review of Current Knowledge

“…Recent animals trials confirm this specific propriety, proving that canola oil has a better effect on pressure, compared to other vegetables oils [50]. Moreover, it has been demonstrated that the supplementation of canola oil, rich of MUFA and α-linolenic acid (ALA), improve glycemic control in diabetic patients with high systolic blood pressure [51].…”