Soybean oil, the most abundant vegetable oil in the world, represents about two-thirds of the edible oil consumed in the United States. Oils from common soybean varieties are high in polyunsaturated fatty acids, providing health benefits, but they are easily oxidized and develop objectionable flavors and odors when heated extensively. Partially hydrogenating the oil makes it more stable against oxidation but also results in formation of trans fatty acids, which present coronary health risks.