Vegetable oils not as healthy as we think

Not all vegetable oils are as healthy as they seem, new research suggests. An analysis in the Canadian Medical Association Journal (CMAJ) has found that some vegetable oils may actually increase the risk of heart disease.

The authors have suggested that Health Canada reconsider cholesterol-lowering claims on food labelling in light of the analysis.

In 2009, Health Canada’s Food Directorate approved a request from the food industry to apply a heart disease risk reduction claim on vegetable oils and foods containing these oils. The label suggests the products offer “a reduced risk of heart disease by lowering blood cholesterol levels”.

“Careful evaluation of recent evidence, however, suggests that allowing a health claim for vegetable oils rich in omega-6 linoleic acid but relatively poor in omega-3 α-linoleic acid may not be warranted,” wrote Dr Richard Bazinet, Department of Nutritional Sciences, University of Toronto and Dr Michael Chu, Lawson Health Research Institute and Division of Cardiac Surgery, Western University, London, Ontario.

According to recent evidence, corn and safflower oil - which are rich in omega-6 linoleic acid but contain almost no omega-3 α-linoleic acid - are not associated with heart health benefits.

In a recent study, one group of participants (the intervention group) replaced saturated fat with sources of safflower oil or safflower oil margarine, while the control made no changes to saturated fat intake. The study organisers found that the intervention group had significantly decreased serum cholesterol levels relative to the control group. However, rates of death from all causes of cardiovascular disease and coronary artery disease significantly increased in the intervention group.

“It is unclear whether oils rich in omega-6 linoleic acid but low in omega-3 α-linoleic acid also reduce this risk,” the authors wrote. “We suggest that the health claim be modified such that foods rich in omega-6 linoleic acid but poor in omega-3 α-linoleic acid be excluded.”