 Few Canadians know much about trans fats, though
most have heard of them.
Reports in the mid 1990s revealed that margarine contains these sinister fats and may not be preferable to butter after all. They’re in most processed and fast foods as well. In the US in 1994 Harvard researchers concluded that trans fats were responsible for over 30,000 annual deaths from heart disease. Other scientists debate these fears.
What They Are / Why They’re Added to Food
Manufacturers hydrogenate (add hydrogen to) corn, soybean, and other unsaturated oils to make them more solid and stable. This makes polyunsaturated and monounsaturated fatty acids more saturated, giving margarines, shortening, and puddings a creamy consistency, and prolongs the shelf life of crackers, cakes, cookies, chips, popcorn, chocolate, and other foods containing the semi-solid oils. Less likely to turn rancid, hydrogenated oils are also often used for deep-frying fast foods. Some un-saturated fatty acids are chemically transformed into trans fats.
The Bad News
Regular unsaturated fats lower blood cholesterol. However, trans fats act more like saturated fats – raising total and LDL (bad) cholesterol. Trans fats also lower protective HDL (good) cholesterol, making them worse than saturated fats. Increasing the risk of diabetes, they may also increase the risk of heart disease by boosting blood triglyceride levels and impairing blood vessel dilation. A 1993 study of nearly 90,000 women found that the risk of heart disease increased 50% among those who ate the most foods high in trans fats (especially margarine). Two recent Dutch studies also found increased coronary risk from high trans fat consumption.
How Much Trans Fat Do We Eat?
Trans fats provide an estimated 4% or more of our total daily calories. No one really knows. A large order of fries or a donut can put you over the average. Also, food manufacturers often change the types of oils and their degree of hydrogenation, so it’s impossible to track. Consumption of hydrogenated oils has increased over the last 15 years as food makers continually use more.
Don’t Trust Food Labels
Foods containing partially hydrogenated oil contain more trans fats, but labels don’t specify how much. Since hydrogenated oils often replace saturated fats, trans fats remain invisible on nutrition labels, as trans fats are not counted as saturated fat. Currently, foods containing trans fats are even permitted to make heart-healthy claims like “no cholesterol” and “low saturated fat.”
A Final Note
Eating small amounts of margarine (or butter, which contains no trans fats) is OK. However, try less, or switch to a healthier type. The more solid the vegetable oil, the more artery-damaging trans fats it has. Soft (tub) margarines contain more unaltered polyunsaturated fats, which help lower blood cholesterol. “Diet” margarines are softest – and less than half the fat. Liquid “squeeze” margarines are also preferable.
Processed and fast foods containing partially hydrogenated oils supply more than two-thirds of the trans fats in our diet. Cut back! Trans fats are only one of the nutritional strikes against them. |
