Liquid at room temperature, these plant- and fish-derived fats can lower cholesterol when they replace saturated fat in the diet.
Credit: Randy Mayor; Leigh Ann Ross

Sources: Vegetable oils like safflower, sunflower, soybean, corn, and sesame oils. Sunflower seeds; soybeans; fatty fish like tuna, mackerel, and salmon; and most nuts are also rich in these fats.

What you need to know: Unsaturated fats garner the most attention when it comes to heart health, and the polyunsaturated type is a good replacement for saturated fat in the diet, says Julia Zumpano, RD, of the Cleveland Clinic's department of preventive cardiology. She also points out that fatty fish like salmon and tuna contain their own special variety of polyunsaturated fats called omega-3 fatty acids. These specific fats appear to keep the heart healthy, even when consumed in small amounts. (One cooked six-ounce salmon fillet offers about 1.6 grams of omega-3 fats, more than an adequate daily amount for these omega-3 fats.) What's more, certain nuts, oils, and greens offer another type of omega-3 fats. A small 2007 study from Penn State finds that eating plant sources of these omega-3 fats, such as flaxseed and English walnuts, likely helps keep bones strong.

Cooking strategies: Use small amounts of nuts and their oils in cooking, says Harvard cardiologist Dariush Mozaffarian, MD, DrPH. Toast nuts and seeds to intensify flavor, and sprinkle them on top of a salad or dish to get the most textural and flavorful impact. A little sesame oil drizzled over fish or a stir-fry adds a nutty tone without excessive calories. And eat more fish. "If you eat only one fatty fish meal per week, that's enough to reap much of the benefits of omega-3s."