Trans Fats,
The Lowdown

Ross Hume Hall, Ph.D.
biochemistry, nutrition,  food technology.

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Prostate Cancer
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Supplement or Not



Saturated fat and cholesterol are supposed to be the culprits in heart disease. Yet health authorities and food companies may be missing a more serious culprit, trans fats. 

And it would be so easy for the food industry to abolish trans fats from the American diet. So why doesn't it?

Denny Lynch, vice president for communications for Wendy’s, was exasperated. The fast-food industry had just completed an expensive changeover of the fat used in deep-fat fryers, from beef fat to vegetable fat. They changed to vegetable fat under pressure from health and nutrition activists.

The activists claimed beef fat with its high content of saturated fatty acids clogs arteries and damages hearts. But now a study at the School of Public Health, Harvard University established a link between the vegetable fat used in fryers to increased risk of heart disease. The New York Times (March 5, 1993, p A10) quotes Lynch, " I wish someone would tell us the right piece of research to go with."

The vegetable fat used in deep fat fryers contains trans fats an unnatural fat formed during refining. The presence of the trans fats was well known before the fast-food industry made the switch. Moreover, researchers already suspected eating the trans fats was unhealthy. Nevertheless, the fast-food industry went ahead with the switch.

Trans Fats Linked to Heart Disease, Breast Cancer

What upset Lynch and other executives in the industry was the new study linked trans fats not only to heart disease but also to breast cancer. A study of European women found that women eating a diet high in trans fats had three times the rate of breast cancer as women eating a diet low in those fats. To be fair, this kind of study is a correlation not necessarily a cause and effect relation.

Dutch researchers found that just one month of eating margarine (rich in trans fats) reduces the normal flexibility of arteries by one third. (Journal Arteriosclerosis, Thrombosis and Vascular Biology,  July, 2001)

Nevertheless, trans fats raise a hefty public health issue. Deep-fried foods are popular, eaten in huge quantities. People love the deep-fried taste. But with the taste, they get a lot of fat. Forty-four percent of the calories of a French fry, comes from absorbed fat. Up to half of that absorbed fat can be trans, a fat now declared dangerous to one’s health.

What’s going on? Is the new research right? Is the refined vegetable oil with trans fat as harmful as beef fat (mostly saturated fat)? Let’s look at the issue from two perspectives: that of the food industry and that of the consumer.

Hydrogenation Produces Trans Fats

A neighbor who does periodic gardening chores for us also works as a part time cook in a local chain restaurant. He tells me that most of the cooking is done in a deep-fat fryer. Restaurants run deep fat fryers from morning to late at night, day after day. I was curious as to how often they changed the oil in the fryer and asked him

"About every 40 days," he said

"Their must be some loss of oil as it absorbs to the food."

"Sure," he said. "But we just top up the fryer every night."

The beef fat, restaurants once used, is practically all saturated fat, solid at room temperature. But at the temperature of a commercial fryer, the beef fat turns liquid. Beef fat holds up reasonably well to days-on-end cooking. Vegetable oil with its high content of unsaturated fat is another matter.

At the searing 355° F (180° C) temperature of the fryer, vegetable oil breaks down, producing toxic byproducts that cause off-tastes and discolor the cooked food. So in making the switch to vegetable oil in their fryers, the restaurant industry needed a quick solution. The answer—hydrogenation.

Hydrogenation, as the name implies, adds hydrogen to the unsaturated fatty acids of the oil. The hydrogenated vegetable oil resists breakdown in a deep-fat fryer. The industry can run deep-fat fryers, as our neighbor mentioned, more than a month between oil changes.

While the food industry gets a benefit from hydrogenation, the consumer gets a distinct disbenefit. Hydrogenation creates those nasty trans fats.

Deep-fried foods are not the only source of trans fats. Hydrogenated vegetable oils have a long shelf life, a factor important to the food industry. The hydrogenated fats are, thus, used extensively in cooking and salad oils, shortenings, crackers, baked goods and frozen meals. Because trans fats occur in so many food products, An average American eats anywhere from 11 to 28 grams a day. The government has determined that for health’s sake a woman should limit herself to 18-20 grams a day of saturated fat. What the government doesn’t tell you is that the trans fat counts as saturated fat.

Thus it’s easy to use up your daily limit of saturated fat through the trans fats, leaving nothing for butter, meat, and other sources of saturated fat. What it really means is that Americans actually eat far more saturated fat than they think they are eating.

Trans Fat Linked to Multiple Health Problems

The health issue, however, remains murky in the sense trans fat does not poison. It doesn’t make you sick to the stomach. Bodily harm may come over the long term and is related to how much of the trans fat a person consumes. But no one knows what amount, if any, is safe.

Mary Enig, a respected researcher, formerly of the University of Maryland, has studied the effects of trans fats on health. In addition to heart disease and breast cancer links, she lists the following negative effects of trans fats.

Interfere with normal function of essential fatty acids

Decrease testosterone and increase abnormal sperm (in animals)

Interfere with pregnancy

Lower quality of breast milk

Decrease insulin response (not good for diabetics)

Change the fat makeup of adipose tissue by incorporating the unnatural trans fats

How do you know if a food product contains trans fats? Nutrition labels do not help. Although, the Food And Drug Administration (FDA) is currently wrestling with a proposal to mandate disclosure of the amount of trans fat in a food product.

Food labels at the moment list amounts of total fat and saturated fat. Manufacturers, as an option, may list monounsaturated and polyunsaturated fats, but are under no obligation to list trans fats.

The whole issue of trans fats is dumb, unnecessary. The vegetable oil industry can easily make vegetable oils suitable for deep-fat fryers that do not contain trans fats. The industry, however, is not noted for taking any lead on matters of health. Until public pressure mounts, consumers of French fries, potato chips and countless other fried foods will continue to get their daily dose of trans fats.


Here are two easy ways to spot trans fats:

1) Any deep-fried food is loaded with those artery clogging trans fats (includes potato chips and similar snack foods).

2) Read between the lines of nutrition labels. If you see the word(s) hydrogenated or partially hydrogenated, it means the food contains trans fats.

© 2001, Ross Hume Hall. All rights reserved.
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