Dear Doctor Column, May 22, 2006

Cutting Harmful Fats for a Healthier Diet

Lately, I’ve noticed the labels on some foods such as potato chips and cookies note the products contain “no trans fats.” Are trans fats different from saturated fats? Why are trans fats so bad, and should I totally eliminate them? If so, what’s the best way to do this?

Answer:

With many Americans concerned about their weight and striving to improve their health through a better diet, there is a new focus on trans fatty acids, or trans fats. In January 2006, the Food and Drug Administration (FDA) began requiring all food manufacturers to list the amount of trans fats in foods along with other nutritional information.

Updated nutritional labels display the total fat content of the food, with the proportion of saturated fat and trans fat listed directly below. Saturated fat and trans fat are not the same, though both raise levels of low density lipoprotein (LDL) cholesterol, the unhealthy type of cholesterol that can accumulate on artery walls and contribute to atherosclerosis and heart disease. In contrast, scientists believe high density lipoprotein (HDL) carries cholesterol away from the arteries and back to the liver, which removes it from the body. Some experts also think HDL helps removes excess cholesterol from arterial plaque, slowing the buildup that can cause heart attack and stroke.

Saturated fat occurs naturally primarily in animal products, and important sources include red meats and full-fat dairy products. Tropical oils such as coconut and palm oil also are saturated fats. Most trans fats are created artificially, although small amounts are found naturally in a few foods. Generally, trans fats are formed through a chemical process called hydrogenation, which adds hydrogen to liquid vegetable oil (forms of monounsaturated or polyunsaturated fat), changing it into a form that is solid at room temperature. This process of hydrogenation prolongs the shelf life of foods. Trans fat not only increases LDL cholesterol levels, it also lowers levels of beneficial HDL cholesterol. Trans fats are found frequently in margarines, crackers, candies, baked goods, cookies, snack foods, fried foods, salad dressing, and a number of other highly processed foods.

Both American Heart Association and the latest US Dietary Guidelines recommend limiting total daily fat intake to 20% to 35% of your daily dietary calories, with 10% or less coming from saturated fat. Trans fat consumption should be kept as low as possible. According to the new FDA regulation, food labels may list the trans fat content of the product as 0 if it contains less than 0.5 grams of trans fat per serving. But even these small amounts of trans fat can add up quickly, especially if you tend to eat more than one serving, which is easy to do with foods such as chips, crackers, and candies.

Check the ingredient list on food labels, looking for the terms “shortening,” “hydrogenated vegetable oil,” or “partially hydrogenated vegetable oil.” If you see any of these ingredients, the food contains trans fat. The closer the ingredient is to the beginning of the list, the more of it is present in the food. Fast foods establishments are not required to report trans fat content of their products, but their foods tend to contain high levels of this harmful substance. McDonald’s recently made headlines when a new testing method revealed a large serving of its French fries contains 8 grams of trans fat, not the 6 grams the company previously claimed.

Cutting down on saturated and trans fat will improve your diet in several ways: foods that are high in these fats also tend to be high in calories and often in sodium as well, and many have little nutritional value. Here are some strategies for reducing saturated and trans fat in your diet:

• Use food labels to make heart-healthy choices. For saturated fat and cholesterol, check the percent daily value, listed as %DV on labels – 5% or less is low, while 20% or more is high. This is based on a daily 2000-calorie diet. If you consume fewer than 2000 calories a day, you will need to use a lower standard.
• While there is not yet enough evidence to establish a recommended daily limit for trans fat intake, remember that US Dietary Guidelines and other health organizations recommend getting as little as possible. Choose foods with a low combined amount of saturated fat, trans fat, and cholesterol.
• Replace saturated and trans fats with healthier fats. You need some fat in your diet to maintain health, and moderate amounts of monounsaturated and polyunsaturated fats do not raise LDL cholesterol and do provide some benefits. Sources include olive oil, canola oil, soybean oil, corn oil, sunflower oil, some fatty fish such as salmon, nuts, and avocados.
• Choose vegetable oils and soft margarines (liquid, tub, or spray) rather than solid shortening, hard margarine, and animal fats, including butter.
• Consider fish. Most fish are lower in saturated fat than meat. Some fish, such as mackerel, sardines, and salmon, also contain omega-3 fatty acids, which offer some protection against heart disease.
• Choose lean meats such as skinless chicken and lean beef and pork with the visible fat trimmed. Broil or bake meats instead of frying.
• In restaurants, ask which fats the chef is using to prepare your food.
• When cutting harmful fats, don’t overlook dietary supplements such as energy and nutrition bars. These products must now also list trans fat content on the supplements facts label.

Source: FDA

For more information on trans fats, visit the FDA site.