The good fats: There are two types of PUFAs, omega-6s, which are found primarily in vegetable oils such as safflower, sunflower, corn, flaxseed and canola oils, and omega-3s, specifically DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), two long-chain PUFAs found primarily in fatty fish, and short-chain ALA (alpha-linolenic acid) that comes primarily from plant-based sources like flax.
The bad fats: Saturated fatty acids are found mainly in animal sources such as meat and poultry, whole or reduced-fat milk and butter. These fats should be consumed in limited amounts. Trans fatty acids are found in vegetable shortening, some margarines, snack foods, cookies and other foods that are made with hydrogenated or partially hydrogenated oils. These fats should be avoided all together.
Both the American Heart Association and the World Health Organization have recognized the association between consuming both PUFAs, but especially omega-3 fats, to optimize heart health.