Low-fat diets are widely recommended as a way to avoid weight gain and promote good health. So it's easy to forget that some fats are necessary for your body to function normally. What matters most is the type of fat you eat, and some of the healthiest types are found in cooking oils that are filled with vitamins and essential fatty acids.
Identification
Most cooking oils come from the seeds of various plants that are crushed and pressed to remove the oil. They are usually liquid at room temperature, although certain types, like coconut and palm oil, may be more solid at room temperature. According to William Sears, M.D., Associate Clinical Professor of Pediatrics at the University of California, Irvine, School of Medicine, most of the oils sold in the supermarket have been processed with potentially toxic substances that improve shelf life and make oil cheap to produce. This is the case unless the product is labeled "unrefined."
Types
Unsaturated fats, found mostly in plant foods, are often called good fats because they play a number of beneficial roles in promoting good health. There are two types: monounsaturated fats, found in high concentrations in canola, peanut and olive oils; and polyunsaturated fats, found in large concentrations in sunflower, corn, soybean and flaxseed oils. Saturated fats are called bad fats, because too much of these fats can contribute to cardiovascular disease, according to the Harvard School of Public Health. Cooking oils that fall into the saturated fat category include coconut and coconut oil, palm oil and palm kernel oil. Trans fatty acids are the unhealthiest type of all, and any oil can be made into this form by heating it in the presence of hydrogen gas, which creates a solid hydrogenated vegetable oil. One tablespoon of any type of cooking oil contains about 120 calories.
Fatty Acids
Omega-3 and omega-6 are types of essential fatty acids that your body can't make on its own. You need to get them from your diet. Many nutrition experts believe that before the advent of processed foods, humans consumed omega-3 and omega-6 fatty acids in equal amounts. Omega-3 fatty acids are linked to a host of beneficial health effects, from helping prevent cancer cell growth to lowering cholesterol and triglycerides in your blood. Omega-6 fatty acids are important for brain health, but can increase inflammation when not balanced with omega-3s. Some oils, like canola, have an almost equal balance of these two types of fatty acids.
Other Nutrition
About 60 percent of vitamin E in your diet comes from vegetable oil or products made with vegetable oils, including sunflower, safflower, canola, olive and wheat germ oils. One tablespoon of olive oil provides 10 percent of the recommended daily value for vitamin E, as established by the USDA. Wheat germ oil has 135 percent of the daily value of vitamin E. Some vegetable oils also contain high levels of vitamin K, particularly olive, canola and soybean oil, with the latter providing 25 micrograms per tbsp. The Daily Value of vitamin K is set at 65 micrograms for women and 80 for men.
Significance
Fats and oils supplied Americans with 45 percent of their calories in the 1960s, but only 13 percent of people were obese, and less than one percent had type 2 diabetes, according to the Harvard School of Public Health. Today, Americans consume only 33 percent of calories from fats and oils, yet 34 percent are obese and 8 percent have a form a diabetes, mostly type 2. The total amount of fat isn't the problem, says Harvard researchers, it's the type of fat that matters. The bad saturated and trans fatty acids increase your risk of heart disease. Good monounsaturated and polyunsaturated fats have heart-protective effects, stabilize blood sugar levels, provide raw materials for making hormones and contribute to a healthy immune system.
Considerations
Cooking at high temperatures can damage oils, according to Dr. Sears. To preserve the nutrients in the oils, it's best to heat them just below boiling and never to the smoking point, which negatively affects the fatty acid content, as well as the taste. You shouldn't use unrefined oils for frying, but they are safe for simmering.
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