Over the past few years, nutrition studies have drawn some unexpected conclusions regarding dietary fat. Eating a low-fat, low-cholesterol diet may not necessarily be the best way to prevent heart disease and maintain good overall health.

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Recent studies have shown that the type of fat may be much more important than the amount of fat. Certain types of fats are unhealthy and the right amounts of some fats actually can be healthy.

What makes a fat good or bad is how the fat affects the level of cholesterol in the bloodstream. Saturated fats and trans fats (the "bad" fats) increase the risk for developing certain diseases, including heart disease. Mono-unsaturated fats and poly-unsaturated fats (the "good" fats) can lower the risk for heart disease and other diseases.

Saturated Fats

Saturated fats are found in most animal-based foods and a few plant-based foods. Meat, poultry, seafood, eggs, and dairy products such as cheese, milk, and ice cream (except skim or no-fat dairy products) all contain saturated fats. Coconut oils, palm oils, and palm kernel oils also contain saturated fat. The American Heart Association (AHA) recommends that people over the age of 2 years limit their intake of saturated fat to less than 7 percent of their total daily calories.

Saturated fats from animal sources increase the level of both "bad" (LDL) cholesterol and "good" (HDL) cholesterol in the bloodstream. It is unclear whether plant-based saturated fats (e.g., coconut, palm, and palm kernel oil) have this same affect on blood cholesterol.

Drinking skim (no-fat) milk and avoiding products that contain tropical oils can help reduce the amount of saturated fat in the diet. Choosing lean meats and low-fat dairy products, and removing the skin from chicken and turkey before eating, are also good ways to reduce saturated fat intake.

While shopping, use the Nutrition Facts label to choose products with the least amount of saturated fat. Based on a 2000 calorie per day diet, saturated fat should be limited to 20 grams or less per day. As an example, 3 ounces of extra lean ground beef has 2.6 grams of saturated fat while 3 ounces of regular ground beef has 6.1 grams of saturated fat. Whole milk has about 3 times the amount of saturated fat as low-fat (1%) milk.

Mono-unsaturated & Poly-unsaturated Fats

Mono-unsaturated and poly-unsaturated fats, which can help improve cholesterol levels, are found in nuts, seeds, and certain plant oils. Mono-unsaturated fats (from canola, peanut, and olive oils) and polyunsaturated fats (from corn, sunflower, and soybean oils) help decrease "bad" (LDL) cholesterol and increase "good" (HDL) cholesterol. Unsaturated fats can account for 20 to 35 percent of the daily calorie intake (e.g., 400-700 calories in a diet consisting of 2000 calories per day).

Trans Fats

Trans fats are considered the most harmful type of fat in the diet. Hydrogenated and partially hydrogenated oils contain trans fat. These fats raise "bad" cholesterol and lower "good" cholesterol. Trans fats are typically found in French fries, peanut butter, microwave popcorn, cookies, chips, and crackers. In general, avoid foods made with hydrogenated and partially hydrogenated oils.

In November 2013, the U.S. Food and Drug Administration (FDA) stated that partially hydrogenated oils (PHOs)—the primary source of artificial trans fat in processed foods—are not "generally recognized as safe." Although artificial trans fat consumption has declined over the past several years, the current intake remains a substantial public health risk.

The FDA and other health organizations concluded that trans fat provides no known benefits and there is no safe level of consumption. It is recommended that people consume as little trans fat as possible. Additional research is being conducted and other determinations are forthcoming.

In June 2015, the FDA finalized its determinations—stating that food manufacturers will have 3 years to remove PHOs from products. Within this compliance period, companies must reformulate food products without partially hydrogenated oils or petition the FDA to allow their specific use. According to the FDA, many companies will eliminate PHOs from their products ahead of the compliance date.

Updated by Remedy Health Media

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 14 Feb 2007

Last Modified: 28 Sep 2015