The 20th century saw big changes in human food supplies. The most dangerous ingredient which was added to food for the first time in human history was industrially produced trans fats in partially hydrogenated oils. These were introduced during the early twentieth century, and by the 1980s consumption of partially hydrogenated oils with trans fats grew to a sizable 8% of all calories consumed by Americans. It was widely used in cookies, crackers, chips, margarines and shortenings as well as fried, frozen and baked goods.