Trans fat is man-made fat formed by artificially “transforming” polyunsaturated liquid fats (corn, soybean, safflower, sunflower, and cottonseed oils) to solid fats. Trans fats are entirely man-made (e.g. they do not exist anywhere in nature) and are the worst possible type of fat one can consume. While trans fat is technically still a type of polyunsaturated fat, the body cannot make use of them. Additionally, they inhibit the body’s ability to utilize healthy polyunsaturated fats like omega-3s.
Plain and simple, avoid trans fats altogether. It is considered by many doctors to be the worst type of fat you can eat.
How Do Trans Fat Affect Health?
Trans fats are bad for the heart. The consumption of them increases the risk of coronary heart disease1 by contributing to increased levels of unhealthy LDL cholesterol and decreased levels of healthy HDL cholesterol. Additionally, trans fat promotes inflammation, an overactivity of the immune system that has been linked to heart disease, stroke, and diabetes.2 They also contribute significantly to weight gain. To reduce the risk of heart problems and unintended weight gain, avoid products containing them.
Where Is Trans Fat Found?
Trans fats are found in margarine and hydrogenated vegetable oils. Trans fats can also be found in many foods including fried foods like doughnuts, and baked goods including cakes, pie crusts, biscuits, frozen pizza, cookies, crackers, and margarines and other spreads. If a food label reads “hydrogenated” or “partially hydrogenated,” the food contains it. Additionally, any food fried in polyunsaturated vegetable oils will contain them.
Cooking at home with polyunsaturated oils at high temperatures may also produce trans fats. Therefore, it is advisable to cook with monounsaturated oils, like olive oil, or even a saturated fat, like butter, because it does not transform into a trans fat.
1. Food and Nutrition Board IoMotNA. Dietary Reference Intakes for Carbohydrates, Fiber, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). National Academic Press; 2005.
2. Mozaffarian D, Pischon T, Hankinson SE, et al. Dietary intake of trans fatty acids and systemic inflammation in women. Am J Clin Nutr. Apr 2004; 79 (4): 606-612.