Fractionating oil is a process most often used on palm and palm kernel oil that involves heating the oil, then cooling it quickly so that it breaks up into fractions (hence the name). The fractioned oil is then passed through a filtration process, during which it's separated into liquid palm olein and solid palm stearin components. Don't worry if you're confused (we are too!). The key thing is that the filtration process separates out most of the liquid part of the oil, leaving a high concentration of solid fat behind.
Fractionated oil is great in preventing the chocolate coating on candy and protein bars from melting, but unfortunately it's not so kind to your waistline or health: "Palm kernel oil is about 80 percent saturated fat and leads to increased LDL (bad) cholesterol," says Christine Gerbstadt, M.D., R.D., a spokesperson for the Academy of Nutrition and Dietetics. So avoid both fractionated and regular palm kernel oil.
Palm fruit oil, however, has less saturated fat and some vitamin E (a player in maintaining a healthy immune system and metabolism), so it's better for you, but still not as healthy extra-virgin olive, canola, avocado, or almond oils, all of which are made up of a majority of mono- or polyunsaturated fats and have medium or high smoke points, making them safe to cook with.