How Bad Are Trans Fats?

Some of the most worrisome fats in human diets are the trans fatty acids found in shortening, margarine and processed foods such as cookies and crackers. Although trans fats have been removed from many foods, they are still present in a variety of baked goods and other products.
Researchers have been concerned that eating foods with trans fats could raise blood sugar and insulin levels. Harvard scientists have analyzed the results from seven trials and found that trans fats did not raise blood sugar but do send total and LDL cholesterol soaring. Good HDL cholesterol dropped significantly. These negative effects on blood fats suggest that it still makes sense to search for foods without trans fatty acids to protect your heart.
[American Journal of Clinical Nutrition, November, 2012]