Hydrogenated oils are oils that have been put through a horrid hydrogenation process to make them either semi-hard or hard, like margarine and shortening. They're also called TransFats. The hydrogenation process renders these oils extremely harmful to the body. Basically, they are guilty of what butter and lard has been accused of for years now--hardening of the arteries. There're quite a few topics on the subject if you'd like to search the forum.