Results from a parallel design, randomized trial indicated that hemoglobin A1c (HbA1c), a marker of long-term presence of excess glucose in the blood, was significantly lower following the three months of the low glycemic-load diet with a canola oil–enriched bread supplement, compared with a whole-grain diet with a whole-wheat bread supplement, according to findings published in Diabetes Care.
“This study shows the advantage of using canola oil in type 2 diabetes to improve both blood cholesterol and blood glucose control by reducing the glycemic load (GI multiplied by the amount of carbohydrate in the diet), especially in those at highest risk of diabetes complications,” said lead researcher Professor David Jenkins from the University of Toronto.
“These findings are timely since diabetes is expected to double in the next 20 years and means of preventing it and its complications are major concerns of governments and the general public.”
The study’s findings were welcomed by the Canola Council of Canada, which sponsored the study along with the Government of Canada. “The ability of canola oil to help control blood glucose in people with type-2 diabetes adds to existing evidence of several health benefits, including CVD risk reduction,” said Shaunda Durance-Tod, MSc, R.D., CanolaInfo manager, Canola Council of Canada.
“Further studies are now warranted on the effect of canola oil in a Mediterranean-type diet on glycemic control, blood fats and weight loss in type-2 diabetes.”
The Canadian scientists recruited 141 type-2 diabetics being treated with oral anti-hyperglycemic agents. Participants were randomly assigned to one of two groups: a low Glycemic load diet with canola oil–enriched bread supplement (31 g canola oil per 2,000 kcal) or a whole-grain diet with a whole-wheat bread supplement.
Results showed that, for the 119 participants who completed the three month trial, HbA1c units decreased by an average of 0.47% in the canola group, compared with 0.31% in the whole grain diet. The difference between the groups was statistically significant, said the researchers. Participants at increased risk for adverse effects from type-2 diabetes, such as those with high blood pressure, derived the greatest benefits, they added.
Cardiovascular disease risk, as measured by the Framingham risk score for CVD, was reduced in both groups, with greater reductions in the canola oil group.
“The reduction of glycemic load by increasing the intake of MUFA and ALA (e.g. canola oil) to displace dietary carbohydrates and reduce the glycemic load improved glycemic control, particularly in participants at high risk for diabetes complications, and reduced LDL-cholesterol, a feature not seen with similar low-GI diets,” wrote the researchers.
“By contrast, whole-grain cereals appear to improve vascular reactivity, possibly helping to explain their benefit in CVD risk reduction.”
Source: Diabetes Care
Published online ahead of print, doi: 10.2337/dc13-2990
"Effect of Lowering the Glycemic Load with Canola Oil on Glycemic Control and Cardiovascular Risk Factors: A Randomized Controlled Trial"
Authors: DJ.A. Jenkins, C.W.C. Kendall, V. Vuksan, et al.