When It Comes to Fats, Limit the Worst - Trans Fats

If it seems as if the recommended guidelines for healthful eating keep changing all the time….well, they do. The reason: In just the past few years, research into how diet can affect health and prevent disease has expanded almost as fast as the obesity rate in the United States. During the past year, the National Academy of Sciences' Institute of Medicine (IOM) announced national dietary guidelines that recommend more fats in the diet but fewer carbohydrates.

More fats for an already too-fat population? Yes, but more of the good fats - including lean fish and poultry, nuts, and olive, peanut and canola oils - and far less of the bad fats. Bad fats include the saturated fats from certain meats, butter, cream and some oils that can raise cholesterol levels and increase the risk of heart disease; plus one other fat that has shot to the top of the bad foods list - trans fatty acids, or trans fats. Government health authorities are so concerned over the health consequences of trans fats, they will soon require their content be listed on those familiar Nutrition Facts food labels.

"Sometimes it's a struggle for patients and their physicians to keep up with the ever-changing dietary guidelines," admits Joan M. Neuner, MD, MPH, Assistant Professor of Medicine (General Internal Medicine) at the Medical College of Wisconsin. "Patients are understandably confused. But I try to tell them that nothing dramatic has really changed. In general, science keeps returning to the overall principle - that Americans are eating too many calories and not getting enough exercise."

Dr. Neuner noted that when she graduated from medical school 10 years ago, US researchers were just beginning to observe the rise in obesity and related conditions like diabetes and heart disease. At the same time, as computers began proliferating, the lives of American adults and children were becoming increasingly sedentary. Men and women were working longer hours, families were spending more time commuting. And food manufacturers were rapidly churning out more convenience foods to meet the rising demand. Suddenly, the obesity rates began to soar.

"It's amazing," Dr. Neuner says. "We knew obesity was on the rise, but no one expected it to skyrocket so quickly." That's one reason so much nutrition research is being published - including a great deal about the new interest in trans fats.

What Are Trans Fats?
What are trans fats anyhow? (Late-night comedian Jay Leno recently quipped that it sounds like an airline: "Next time, fly trans fat," he joked.) Actually, trans fats are man-made fats that occur in foods when manufacturers use hydrogenation, a process in which hydrogen is added to vegetable oil to turn it into a more solid fat.

Trans fats are found in vegetable shortening, some margarines (especially stick margarines), crackers, candies, cookies, snack foods, fried foods, baked goods, salad dressings, and other processed foods harried Americans have been buying in recent years. A story in the Dec. 1, 2003, issue of Newsweek estimates trans fats are now found in more than 40% of foods on grocery shelves. "They show up in fresh foods, making croissants flaky and pie crusts crumbly. But they're also what's keeping that decade-old Twinkie at the back of your pantry soft," the magazine said.

'Trans Fats Are Bad': Tommy Thompson
"Trans fats are bad fats. The less trans fat you and I eat, the healthier we will be," Health and Human Services Secretary Tommy Thompson said on July 9 when he announced that the US Food and Drug Administration (FDA) had issued a regulation requiring manufacturers of processed foods and some dietary supplements to list the trans fat content on the Nutrition Facts panel included on food and supplement labels. The regulations are mandatory beginning in 2006. It is the first significant change on the Nutrition Facts panel since it was established in 1993.

Like saturated fats from animal products, trans fats can raise cholesterol levels and increase the risk of heart disease. Even worse, trans fats can also raise triglycerides and lower the level of the so-called good cholesterol, or the high-density lipoproteins (HDLs), while increasing the levels of the bad cholesterol, or LDLs, the low-density lipoproteins.

Under the new FDA regulations, after Dec. 31, 2005, consumers will be able to find trans fats listed on food labels directly under the line for saturated fat. Many foods contain several different kinds of fat - including saturated, polyunsaturated, monounsaturated and trans fat. What do they all mean?

Saturated fat: Found in eggs, butter, meat, poultry, chocolate, coconut, palm oil and lard.
Polyunsaturated fat: Found in some vegetable oils such as safflower, corn, sunflower, soy and cottonseed oils.
Monounsaturated fat: The "good" fat, found in fish and lean poultry, avocados, nuts, and olive, peanut and canola oils.
Trans fat: Found in many margarines and shortenings, and in commercial baked goods and fried foods.

Fats Are Essential to Health
First, it's important to note that, under the most recent recommendations from the National Academy of Sciences' Institute of Medicine, fats should make up between 20% and 35% of your daily dietary intake, mostly from the so-called good fats. Fats are an essential part of a daily diet; they aid the absorption of many essential vitamins, help maintain the structure and function of cell membranes and help boost your body's immune system. Too much fat, of course, can increase your risk of heart disease, diabetes and obesity. Under the guidelines, the recommended daily intake of carbohydrates has been lowered, from 55% to 45%.

How much trans fat should you eat a day? "The guidelines don't tell us specifically," Dr. Neuner says. "The IOM guidelines do say to limit saturated fat to 10% a day, but nothing about trans fat." (The FDA Fact Sheet What Every Consumer Should Know About Trans Fatty Acids merely says that no research is currently underway to determine the daily limit. It adds, however: "It is true and accurate to say that the less saturated fat, trans fat and cholesterol consumed the better. Trans fat, while pervasive in many of the foods we eat, is not 'essential' to any healthy diet.")

To find out if a food contains trans fats, look for the term hydrogenated or partially hydrogenated in the list of ingredients on the food label. If they are part of the recipe, use sparingly.

And even though manufacturers are not required to list trans fats on their Nutrition Facts labels until 2006, some, such as Frito-Lay, have already begun to do so voluntarily. Manufacturers of foods that are low in saturated fat and trans fat have begun marketing around their products' health benefits. Consumers should be cautious, however, Dr. Neuner says.

Read Labels Carefully
"Many foods contain several kinds of fats," Dr. Neuner says. "Read the labels carefully. I'd be suspicious unless I had all the information." Some foods, such as Newman's Own popcorn, claim they contain no trans fats - but they do contain palm oil, a saturated fat.

Now that Americans are told to add more fats to their diets but avoid or sharply limit the saturated and trans fats found in so many favorite foods, what's next? Stick with the basics, Dr. Neuner recommends.

"This really isn't such a sea change from what we already know," she says. "We'll continue to refine the details, but the main message is the same: Eat fewer calories and get more exercise. Be cautious with processed foods, and choose more fruits and vegetables as snacks as often as possible."

Barbara Abel
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.