November 12, 2013
Heart Disease Risk From ‘Healthy’ Vegetable Oils
April Flowers for redOrbit.com - Your Universe Online
A new study, published in the Canadian Medical Association Journal reveals that some vegetable oils that claim to be healthy might actually increase the risk of heart disease. Due to the results, the research team is now calling for Health Canada to reconsider cholesterol-lowering claims on food labeling based on their findings.
It has become common practice to replace saturated animal fats with polyunsaturated vegetable oils because the polyunsaturated oils can reduce serum cholesterol levels and help prevent heart disease. Health Canada's Food Directorate reviewed published evidence in 2009, approving a request from the food industry to apply a heart disease risk reduction claim on vegetable oils and foods containing these oils. A "reduced risk of heart disease by lowering blood cholesterol levels" is suggested by the label.
"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-linolenic acid may not be warranted," write 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.
Corn and safflower oil are rich in omega-6 linoleic acid, but contain almost no omega-3 α-linolenic acid. These oils are not associated with beneficial effects on heart health, according to recent studies. The current research team cites a prior study published earlier this year, "… in which the intervention group replaced saturated fat with sources of safflower oil or safflower oil margarine (rich in omega-6 linoleic acid but low in omega-3 α-linoleic acid). They found that the intervention group had serum cholesterol levels that were significantly decreased (by about 8%-13%) relative to baseline and the control group, which is consistent with the health claim." The rates of death, however, from all causes of cardiovascular disease and coronary artery disease significantly increased in the treatment group.
Omege-6 linoleic acid is found in mayonnaise, margarine, chips and nuts, as well as the corn and safflower oil. In Canada, the most commonly used forms of oil are canola and soybean, which contain both linoleic and α-linolenic acids.
The researchers say, "It is unclear whether oils rich in omega-6 linoleic acid but low in omega-3 α-linolenic acid also reduce this risk. We suggest that the health claim be modified such that foods rich in omega-6 linoleic acid but poor in omega-3 α-linolenic acid be excluded."