Ask the Nutritionist: Figuring Out Fats

I’ve heard over and over again that trans fat is bad for us. What I’m not sure of is what it is. And why is it bad?

Trans fat is formed when unsaturated oils are put through a chemical process called hydrogenation. That makes the oils solid at room temperature—think margarine or vegetable shortening. Hard fat is necessary to achieve specific characteristics in certain foods. For example, without a hard fat, crackers would be soft, pies and croissants would lose their flakiness, and foods would go rancid more quickly.

Not all hard fats are trans fats though; some are saturated fats (the kind found in butter and cocoa butter, palm and coconut oils). But several years ago, the food industry moved away from using saturated fat because of its association with increased LDL (“bad” cholesterol) levels. In making this switch, the industry unknowingly created a fat that has turned out to be even worse for health: trans fat. In recent years, scientists have discovered that trans fatty acids not only raise LDL levels, they lower HDL (“good” cholesterol)—increasing your risk factors for heart disease.

The new US Dietary Guidelines flatly state that people should minimize their intake of trans fat while still maintaining a healthful diet.

What sorts of foods contain trans fat?

Most of the trans fat that we eat is found in fast food and highly processed foods such as cookies, crackers, chips, doughnuts and french fries. Minute quantities occur naturally in dairy products and meats. If you’re worried about whether a product contains trans fat, look on the ingredients label for the term “partially hydrogenated.” Partially hydrogenated oil is trans fat. Unfortunately, you won’t be able to tell from the label how much trans fat is in your food. At least, not yet. As of January 1, 2006, the US Food and Drug Administration (FDA) will require nutrition labels to list the grams of trans fat in all processed foods. There are already a growing number of products labeled “no trans fat.”

Because manufacturers will be forced to put trans fat info on nutrition labels next year, many companies—in an effort to show how healthy their foods are—are working on new formulations that will be free of this fat. For instance, Nabisco is producing Triscuits and several varieties of Oreos that are free of trans fat, and Frito-Lay has managed to zap every gram of trans fat in Tostitos.

Many companies have already switched from trans fatty acids to healthier, monounsaturated oleic acids (found in sunflower, olive and canola oils). But some manufacturers in the baking industry are having a hard time finding a healthful substitute and may return to traditional saturated fats such as butter or tropical oils. So even if a food is free of trans fat, don’t assume it’s healthful. Check the label.

Some consumer groups and scientists are lobbying to reduce—or even ban— trans fat in our foods and to force restaurants to disclose their use of trans fat in cooking. McDonald’s relies on trans fat to cook its famous french fries. Though the company has promised to stop, it hasn’t found a replacement yet.

So far, the FDA is resisting a ban. A report from the National Academy of Sciences’ Institute of Medicine states, “Because they are not essential and provide no known health benefit, there is no safe level of trans fatty acids, and people should eat as little of them as possible while consuming a nutritionally adequate diet.”

I have diabetes, but so far I’ve been able to control it with diet and exercise. I want to avoid the large quantities of beans and breads often found in vegetarian recipes. How can I get the protein I need and still keep the carbs low?

It’s terrific that you’re controlling your diabetes with diet and exercise. But as a diabetic, regardless of what the low-carb gurus say, you don’t need to avoid high-carbohydrate foods such as legumes and breads. In fact, just that actually helps manage diabetes and even reduces the incidence of it.

Beans and other legumes are full of healthful complex carbohydrates that only negligibly increase blood glucose. Legumes are also full of protein, fiber and antioxidants—important protectors against heart disease and cancer. Whole grains contain nutrients such as vitamin E and magnesium, which may help improve insulin resistance, says Joanne Slavin, professor of food science and nutrition at the University of Minnesota, St. Paul. Research tells us that people who eat more whole grains are slimmer and are less likely to have diabetes and heart disease than people who swear off these healthful carbs.

Glucose (sugars used by the brain and body for energy) is carried to the cells by insulin. Diabetics either have a deficiency of insulin (type 1 diabetes) or a resistance to insulin (type 2), which causes high blood glucose levels. The most important natural ways to keep blood glucose in check and minimize medications are to maintain a healthy weight and to exercise— physical activity helps clear glucose from the blood stream.

Extremely high-protein, low-carb diets are risky for diabetics because they’re so high in cholesterol and saturated fat—both invite heart disease, the leading cause of death for people with diabetes.