On June 17th, the Food and Drug Administration ended a battle that started a quarter century ago. The FDA banned partially hydrogenated oil, the source of artificial trans fat. The food industry will ask the FDA to allow specific amounts in certain foods, but I hope the FDA permits only levels that won’t harm consumers.
Food with trans fat entered our food supply more than a century ago, when chemists found that reacting liquid oils with hydrogen turned them into more-solid fats. That led to shortenings like Crisco (which replaced lard, butter, and beef tallow) and stick margarines. After World War II, the floodgates opened. Partially hydrogenated oils were cheap and shelf stable, and companies began to use them in thousands of foods.