Quick Facts

Trans fat is the most unhealthy and dangerous common nutrient in the American diet. Even in small amounts, artificial trans fat from partially hydrogenated vegetable oils can be deadly:
Adding just a single gram of trans fat to your daily diet raises your risk of coronary heart disease by 20%.
As many as 100,000 deaths by coronary heart disease would be avoided every year if Americans ate less trans fat.
Gram for gram, trans fat is far worse for your cholesterol and cardiovascular health than saturated fat.
High trans fat consumption raises your risk of type 2 diabetes by about 40% over low trans fat consumption.
High trans fat consumption raises women’s risk of breast cancer by about 75% over low trans fat consumption.
There is no nutritional reason to eat any artificial trans fat whatsoever. It is best to avoid artificial trans fat completely.
The Deadly Effects of Trans Fat: Heart Disease
After decades of research, the link is clear. Trans fat causes coronary heart disease (CHD), the leading cause of death for both men and women in the United States.

The American Heart Association concludes, “trans fats raise your bad (LDL) cholesterol levels and lower your good (HDL) cholesterol levels. Eating trans fats increases your risk of developing heart disease.” The U.S. Department of Health and Human Services and the U.S. Department of Agriculture agree, writing, “The relationship between trans fatty acid intake and LDL cholesterol is direct and progressive, increasing the risk of cardiovascular disease.”

Trans fat narrows and hardens your arteries, constricting blood flow to your heart and causing cardiac arrest.

Per calorie, artificial trans fat raises the risk of heart disease more than any other nutritive product, including saturated fats like beef fat. Just small amounts of trans fats can have a large impact on your health. In fact, researchers estimate that removing trans fat equivalent to 2% of daily calories from the American diet would prevent approximately 30,000 premature coronary deaths per year, and evidence suggests the number may be closer to 100,000 deaths.

Further Reading:

The American Heart Association provides basic information about trans fats on its official website.
“The negative effects of trans fats and what to do about them” reviews the health effects of trans fats and recommends a complete ban. Published by Atherosclerosis, 2009, written by Professor Fred Kummerow of the University of Illinois.
“Trans Fatty Acids and Cardiovascular Disease” provides an in-depth scientific review of the dangers of eating trans fats. Published by the New England Journal of Medicine, 2006, written by Professor Dariush Mozaffarian of the Harvard School of Public Health.
In her 2009 editorial for Annals of Internal Medicine, “Safer Fats for Healthier Hearts: The Case for Eliminating Dietary Artificial Trans Fat Intake,” former director of the U.S. Center for Disease Control and Prevention (CDC) Dr. Julie Gerberding argues that the FDA should be prepared to ban all artificial trans fats.
The Deadly Effects of Trans Fat: Diabetes
Trans fat can cause type 2 diabetes because it disrupts the body’s glucose and insulin regulation system. When trans fats take the place of natural fats in your cell membranes, insulin receptors on cell walls malfunction, elevating blood glucose levels and stimulating further release of insulin. Over time, this condition leads to diabetes.

Further Reading:

“Diet, Lifestyle, and the Risk of Type 2 Diabetes Mellitus in Women” by Frank B. Hu followed 84,941 female nurses over 16 years and found that consumption of trans fat leads to a higher risk of developing type 2 diabetes. Published in the New England Journal of Medicine, 2001.
In “Dietary fats and prevention of type 2 diabetes,” Ulf Riserus gives an overview of the scientific literature on the relationship between types of dietary fat and diabetes risk. Published in Progress in Lipids Research 2009.
The Deadly Effects of Trans Fat: Cancer
Besides heart disease and diabetes, trans fat is a carcinogen that causes high rates of breast, prostate, and colorectal cancer. Various studies have shown that men and women who consume the most trans fat have a 58-100% greater risk of developing one of these cancers than those who consume the least trans fat.

Further Reading:

“A Prospective Study of Trans-Fatty Acid Levels in Blood and Risk of Prostate Cancer” by Jorge E. Chavarro is a detailed study into the relationship between trans fat in the body and men’s risk for prostate cancer. Published by the journal Cancer Epidemiology, Biomarkers, and Prevention, 2008.
“Association between Serum trans-Monounsaturated Fatty Acids and Breast Cancer Risk” by Veronique Chajes finds that higher levels of trans fat in the bloodstream raise women’s risk of breast cancer. Published in the American Journal of Epidemiology, 2008.
“Intake of conjugated linoleic acid fat, and other fatty acids in relation to postmenopausal breast cancer,” by Laura Voorrips, find that trans fatty acid intake increases the incidence of breast cancer. Published in The American Journal of Clinical Nutrition, 2002.
Partially hydrogenated vegetable oil looked like a wonder product when it was first invented, but now we know it is a killer.