In 1957, a fledgling nutrition scientist at the University of Illinois persuaded a hospital to give him samples of arteries from patients who had died of heart attacks.
When he analyzed them, he made a startling discovery. Not surprisingly, the diseased arteries were filled with fat — but it was a specific kind of fat. The artificial fatty acids called trans fats, which come from the hydrogen-treated oils used in processed foods like margarine, had crowded out other types of fatty acids.