The health scourge of the 2000s, trans fats were invented for a practical purpose. In the late 1800s, people began adding hydrogen to oils like vegetable oil to increase the shelf life of foods. But modern studies found that the combination, which does not occur naturally, had unforeseen health consequences, contributing to a rise in bad cholesterol and increasing the risk of heart disease. Manufacturers like McDonald's raced to remove trans fats from their foods, and in 2006, food manufacturers in the U.S. were required to label the amount of trans fats included in their products.