One Type of Unsaturated Fat Increases Risk of Heart Disease, Study Shows

The conventional wisdom that unsaturated fats are harmless to the heart is wrong, according to a report in today’s New England Journal of Medicine. A 14-year study of more than 80,000 female nurses found that one type of unsaturated fat--so-called trans-unsaturated fat--actually increases the risk of heart disease. The study does support the well-established notion that the saturated fat found in red meat and dairy products is harmful.

Using data from the Nurses’ Health Study, Dr. Frank B. Hu of the Harvard School of Public Health and his colleagues found that replacing 5% of a woman’s energy intake from saturated fat with energy from two types of unsaturated fats--mono-unsaturated fat and polyunsaturated fat--reduced heart disease risk by 42%. But they also found that cutting out 2% of a woman’s intake of trans-unsaturated fat and replacing it with mono-unsaturated fat or polyunsaturated fat reduced the risk of heart disease by a hefty 53%. Trans-unsaturated fats are hardening agents found in margarines, shortening, packaged cookies, crackers and many fast foods.