Trans fats are a cholesterol double whammy. Also known as trans-fatty acids, they raise low-density lipoprotein (LDL, or “bad” cholesterol) and lower high-density lipoprotein (HDL, or “good” cholesterol).
Experts consider trans fat the worst type of dietary fat, contributing to heart disease by promoting low-grade inflammation in the blood vessels. Trans fats are also associated with a higher risk of developing type 2 diabetes, according to the April issue of Mayo Clinic Women’s HealthSource.
Trans fats are formed when liquid oils are made into solid fats like shortening and hard margarine. Because of their long shelf life and appealing texture, synthetic trans fats have been favored ingredients in commercially baked goods like cakes, cookies, crackers and crusts. Commercially fried foods like doughnuts and french fries also often contain trans fats.
The use of trans fats is starting to change. New York City made headlines when it banned trans fats in restaurants. Other cities are considering going trans-fat–free, and some food manufacturers are reducing or eliminating trans fats in their products.
But avoiding trans fats still takes diligence. The American Heart Association recommends limiting trans fats to less than 1% of daily calories. That’s just 20 calories (2 grams) in a 2,000-calorie daily diet. This amount can easily come from naturally occurring trans-fatty acids in dairy products and meat from cows, goats and sheep.
At the grocery store, product nutrition labels contain trans-fat information, but a product that has less than one-half gram of trans fat can be labeled as zero. Eating modest amounts of these products can easily add up to more than 2 grams of trans fats. Keys words like “shortening,” “partially hydrogenated” or “hydrogenated” indicate the food contains trans fats, even when the chart on the label indicates none.
Many restaurants continue to use trans fats for deep-fried foods. Grilled or baked foods are more likely to be trans-fat–free.