Some vegetable oils that we consider part of a healthy diet actually increase the risk of heart disease. Health Canada should rethink dietary cholesterol-lowering requirements, according to the Journal of the Canadian Medical Association.
Replacing saturated fats from animal sources with polyunsaturated vegetable oils has become a common practice because they can lower serum cholesterol levels and help prevent heart disease.
In 2009, Health Canada’s Food Administration, after reviewing published data, granted a request from the food industry to address the challenge of reducing the risk of heart disease through advertising for vegetable oils and foods containing these oils. The label now reads: “Reducing the risk of cardiovascular disease by lowering blood cholesterol.”
“Careful evaluation of recent evidence, however, shows that despite their claimed health benefits, vegetable oils rich in omega-6 linoleic acid but relatively poor in omega-3 α-linolenic acid cannot justify it,” Dr. Richard writes. Bazinet from the Department of Nutritional Sciences at the University of Toronto and Dr. Michael Chu from the Department of Cardiac Surgery at the Health Research Institute in London.
Corn and safflower oils, which are rich in omega-6 linoleic acid but low in omega-3 α-linolenic acid, have not been found to benefit heart health, according to recent findings. The authors cite a study published in February 2013: “Replacing saturated fat in the diet of the control group with safflower oil (rich in omega-6 linoleic acid but low in omega-3 α-linoleic acid) led to a significant reduction in cholesterol levels (they fell by about by 8% -13%). However, mortality rates from cardiovascular disease and coronary heart disease have increased significantly.”
In Canada, omega-6 linoleic acid is found in corn and sunflower oil, as well as foods such as mayonnaise, margarine, chips, and nuts. Canola and soybean oils, which contain both linoleic and α-linolenic acids, are the most common oils in the Canadian diet. “It is unclear whether oils rich in omega-6 linoleic acid but low in omega-3 α-linolenic acid can reduce the risk of heart disease. We believe that foods rich in omega-6 linoleic acid but poor in omega-3 α-linolenic acid should be excluded from the list of cardioprotectors,” the authors conclude.