Danish doctors warn that French fries and chicken, coming from the American McDonald's and KFC, may contain more trans fat than those in other countries. Steen Stender and his colleagues from Gentofte University Hospital in Hellerup, Denmark, report in a medical journal that the levels of unsaturated fatty acid, known as trans fat, may vary from country to country. While traveling for other reasons, during November 2004 and September 2005, these doctors ordered "a large serving" of French fries (171 grams) and chicken nuggets (160 grams) in 43 U.S. and international McDonald's or KFC restaurants, analyzing the food's total fat and trans fat content. These fats are found is some margarines and many processed foods made with or fried in partially hydrogenated oils. They raise the levels of "bad cholesterol", or LDL, also increasing the risk of heart disease. The foods with the highest levels of trans fat were found in McDonald's restaurants in New York, Peru, and Atlanta and in KFC restaurants from Hungary, Poland and Peru. "The cooking oil used for French fries in McDonald's outlets in the United States and Peru contained 23% and 24% trans fatty acids, respectively, whereas the oils used for French fries in many European countries contained only about 10% trans fatty acids, with some countries as low as 5% (Spain) and 1% (Denmark)," the researchers said. "McDonald's continues to work diligently on ways to reduce TFA levels in our fries," McDonald's responded in a statement. "Our reduction in the U.S. is taking longer than anticipated, as we have previously announced. However, we continue to progress in our testing and we are determined to get it right for our customers."