I'm not sure I'm answering your question, but I found this link on the Atkins site:

http://atkins.com/Archive/2001/12/15-513651.html

If you go to the Atkins site and at the top in the search box, type in Trans it comes up with just pages and pages of information which might answer your question too.

And I found these quotes in DANDR.

"Do not cook polyunsaturated oils, such as corn, soybean and sunflower oil, at high temperatures or allow to brown or smoke"

"Margarine should be avoided, not because of its carbohydrate content, but because it is usually made of trans fats (hydrogenated oils) which are a serious health hazard. (Some non-hydrogenated margarines are available in health food stores)."

Julie