Fat has gotten a bad rap—but things are beginning to change. Many people don’t know it, but fat is an essential nutrient. It is not only a significant energy source but also provides insulation for nerves and helps with the absorption of fat-soluble vitamins, like vitamins E and A. In addition, certain types of fat—such as omega-3s and monounsaturated fatty acids—have heart health benefits.
Fat building blocks
Fat is made up of fatty acids. There are three main types of fatty acids found in foods: monounsaturated, polyunsaturated, and saturated fatty acids—these names simply refer to the basic structure of the fat. The different fatty acids combine into triglycerides, which is how fat is found in the foods we eat. Take olive oil for example; even though it’s famous for being high in monounsaturated fat, it still contains a small percentage of polyunsaturated fat and saturated fat. The same is true for the fat in other foods, as well.
Types of fats
The important thing to remember about different types of fat is how they affect your body, because not all fats are the same.
- Polyunsaturated fat is usually liquid at room temperature and comes mainly from plant foods, especially their oils. For example, soybean, corn, sunflower, peanut, and sesame oils are all rich in polyunsaturated fat. Studies show that eating more polyunsaturated fats and less saturated fats can help to lower cholesterol levels.
- Omega-3s are a special kind of polyunsaturated fat with numerous health benefits, omega-3s are considered essential fatty acids because we must get them in our diet. They are found in both plant and animal foods. Plant sources include flax oil and seeds, walnuts, canola oil, hemp seeds and oil, and soybean oil. Animal sources are fish such as salmon, lake trout, tuna, herring, mackerel, and sardines. Several brands of eggs and other foods enriched with omega-3s are also now available.
- Monounsaturated fat is usually a liquid at room temperature and tends to have a neutral effect on cholesterol levels, which can help to keep the heart healthy. Avocados, canola oil, and olive oil are terrific sources of monounsaturated fat.
- Saturated fat tends to be solid at room temperature and when eaten in excess can raise cholesterol levels. Animal fat (except most fish), butter, margarines, tropical oils, and many packaged snack products are key sources of saturated fat.
- Trans fat forms when vegetable oils are chemically altered in the process of partial hydrogenation and has been associated with an increased risk for coronary heart disease. A high intake of trans fat seems to increase the levels of both total and LDL cholesterol (the lousy kind) while lowering the level of HDL cholesterol (the happy kind)—the exact opposite of your goals for a healthy heart. The majority of trans fat comes from foods containing partially hydrogenated oils such as margarine, baked goods, fried fast food, cookies, chips, and donuts. New labeling laws require manufacturers to list the amount of trans fat on nutrition facts labels, so read labels.
Quantity versus quality
When you see how the different types of fat can either help or hurt your health, it becomes clear that the quality of the fats you choose is equally if not more important than the quantity you eat. Just keep in mind that fats provide 9 calories per gram, so keep your portions under control. The Institute of Medicine (IOM) recommends getting 20 to 35% of your calories from fat per day.
Changing your oil
- Avoid buying chemically extracted vegetable oils, which have reduced nutrient value, color, and aroma.
- Instead, choose expeller-pressed oils or cold-pressed oils (expeller- and cold-pressing are chemical-free processes in which the oil in a seed or nut is forced out under pressure).
- Store expeller- or cold-pressed oils in the refrigerator so they stay fresh.
- Discard rancid oil—you can tell if oil is rancid by smelling it, it will smell off, even bitter.