Trans fat is a type of dietary fat. Of all the fats, trans fat is the worst for your health. Too much trans fat in your diet increases your risk for heart disease and other health problems.

Trans fats are made when liquid oils are turned into solid fats, like shortening or margarine. These are called partially-hydrogenated oils (PHOs).

Because of the health risks from these fats, the United States Food and Drug Administration (FDA) has banned food manufacturers from adding PHOs to foods.

Although the food industry has greatly reduced the use of trans fat in recent years, this type of fat may still be found in many fried, packaged, or processed foods, including:

• Anything fried and battered
• Shortening and stick margarine
• Commercially baked cakes, pies, and cookies
• Refrigerated dough

Animal foods, such as red meats and dairy, have small amounts of trans fats, which is not cause for concern in its natural form. Most trans fats are artificially made and come from processed foods.

Trans fatty acids; Partially hydrogenated oils (PHOs); Cholesterol - trans fats; Hyperlipidemia - trans fats; Atherosclerosis - trans fat; Hardening of the arteries - trans fat; Hypercholesterolemia - trans fat; Coronary artery disease - trans fat; Heart disease - trans fat; Peripheral artery disease - trans fat; PAD - trans fat; Stroke - trans fat; CAD - trans fat; Heart healthy diet - trans fat

Your body does not need or benefit from trans fats. Eating these fats increases your risk for health problems.

Cardiovascular disease risk:

• Trans fats raise your LDL (bad) cholesterol.
• They lower your HDL (good) cholesterol.
• High LDL along with low HDL levels can cause cholesterol to build up in your arteries (blood vessels). This increases your risk for heart disease and stroke.

Weight gain and diabetes risk:

• Many high-fat foods such as baked goods and fried foods have a lot of trans fat.
• Like all fats, trans fat contains 9 calories per gram. Consuming a lot of fat can lead to unwanted weight gain. Excess weight increases the risk for diabetes, heart disease, and other health problems.

Your body does not need trans fat. You should avoid it or eat as little as possible.

Here are recommendations from the 2020-2025 Dietary Guidelines for Americans:

• You should get no more than 25% to 30% of your daily calories from fats.
• You should limit saturated fat to less than 10% of your daily calories.
• You should use nutrition facts labels to select foods with no trans fat whenever possible.

All packaged foods have a nutrition label that includes fat content. Food makers are required to label trans fats on nutrition and some supplement labels. Reading food labels can help you keep track of how much trans fat you eat.

• Check the total fat in one serving.
• Look closely at the amount of trans fat in a serving.
• Look for the words "partially hydrogenated" in the ingredient list. It means oils have been turned to solids and trans fats. Manufacturers can show 0 grams of trans fat if there are less than 5 grams per serving; often a small serving size shows 0 grams of trans fat, but it still might be in there. If there are multiple servings in a package, then the whole package may contain several grams of trans fat.
• When tracking trans fat, make sure you count the number of servings you eat in one sitting.
• Many fast-food restaurants use solid oils with trans fat for frying. Often they provide nutrition information on their menus. If you do not see it posted, ask your server. You also may be able to find it on the restaurant's website.

Trans fats are found in many processed and packaged foods. Note that these foods are often low in nutrients and have extra calories from both fat and sugar:

• Cookies, pies, cakes, biscuits, sweet rolls, and donuts
• Breads and crackers
• Frozen foods, such as frozen dinners, pizza, ice cream, frozen yogurt, milkshakes, and pudding
• Snack foods
• Fast food
• Solid fats, such as shortening and margarine
• Nondairy creamer

Not all packaged foods have trans fats. It depends on the ingredients that were used. That is why it is important to read labels.

While it is fine to treat yourself to high-fat foods occasionally, it is best to avoid food with trans fats completely.

You can cut trans fat by substituting healthier foods for less nutritious options. Replace foods high in trans and saturated fats with foods that have polyunsaturated and monounsaturated fats. Here is how to get started:

• Use safflower or olive oil instead of butter, shortening, and other solid fats.
• Switch from solid margarine to soft margarine.
• Ask what type of fats foods are cooked in when you eat out at restaurants.
• Avoid fried, packaged, and processed foods.
• Replace meats with skinless chicken or fish a few days a week.
• Replace whole-fat dairy with low-fat or nonfat milk, yogurt, and cheese.

Hensrud DD. Diet and nutrition. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 13.

Mozaffarian D. Nutrition and cardiovascular and metabolic diseases. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 29.

US Department of Health and Human Services; Food and Drug Administration. Trans fat. www.fda.gov/food/food-additives-petitions/trans-fat. Updated April 30, 2024. Accessed May 21, 2024.

US Department of Health and Human Services; US Department of Agriculture. 2020 - 2025 Dietary Guidelines for Americans. 9th Edition. www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf. Accessed June 11, 2024.