Health Tips - Dietary Fats
Dietary Fats Guide
Dietary fats are chemical compounds composed of carbon, hydrogen, and oxygen, and are found in a variety of foods, including animal products, seeds, nuts, and vegetables. The amount and type of dietary fat that should be present in a healthful diet has been the source of tremendous controversy in recent years.
Dietary fat supplies 9 calories per gram (compared to 4 calories per gram from carbohydrates and protein) and aids in the absorption and transport of the fat-soluble vitamins ( vitamin A, vitamin D, vitamin E, and vitamin K) and other fat-soluble nutrients. Fat improves the taste and feel of food and provides a sense of satiety; dietary fat also provides essential fatty acids that the body cannot synthesize on its own, but requires for many normal physiological processes. Eating too much of the wrong kinds of fat increases the risk of obesity, heart disease, and cancer. As a result, nutritionists and physicians often recommend that people reduce their total fat, saturated fat, and trans fat intake.
Dietary fats are divided into four main categories: saturated fats, monounsaturated fats (MUFAs), polyunsaturated fats (PUFAs), and trans (or hydrogenated) fats. These fats are distinguished by the structure of the fatty acids they contain. Fatty acids are made up of carbon atoms arranged in chains of varying length, to which a variable number of hydrogen and oxygen atoms are joined. The structure of the carbon chain may or may not include a double bond between the carbon atoms; a chain containing double bonds will hold fewer hydrogen atoms than a chain containing only single bonds. Foods often contain a mixture of different fatty acids, but can be categorized by the fatty acids most prevalent in the food.
Saturated Fats (coconut, palm, tropical oils; butter; lard)
Saturated fats contain large amounts of saturated fatty acids. Saturated fatty acids are so named because they are saturated with hydrogen, meaning they have only single bonds between carbon atoms, leaving no room in their chemical structure for additional hydrogen atoms. Saturated fats are typically solid at room temperature.
Monounsaturated Fats (almond, avocado, canola, olive, peanut oils)
Monounsaturated fats contain large amounts of monounsaturated fatty acids (MUFAs). MUFAs are so-named because, due to the presence of one double bond in the carbon chain, the fatty acid is not saturated with hydrogen. Monounsaturated fats are typically liquid at room temperature, but solidify when refrigerated
Polyunsaturated Fats (corn, flaxseed, hemp, pumpkin seed, safflower, sesame, sunflower oils)
Polyunsaturated fats contain large amounts of polyunsaturated fatty acids (PUFAs). Polyunsaturated fatty acids are so-named because, due to the presence of two or more double bonds, there are places along the carbon chain where the fatty acid is not saturated with hydrogen. Polyunsaturated fats are liquid at room temperature, and remain in liquid form even when refrigerated or frozen. Polyunsaturated fats are divided into two families: the omega-3 fats and the omega-6 fats.
Trans-Fats (hydrogenated vegetable oils, margarine, partially-hydrogenated oils, vegetable shortening)
Trans fats are produced through hydrogenation, a chemical process by which hydrogen is added to unsaturated fatty acids. Hydrogenation converts the unsaturated bonds in the oil into saturated bonds, creating a solid, spreadable fat with increased shelf life. Hydrogenation gets rid of some double bonds, but incompletely transforms others. These double bonds are transformed from the natural cis configuration to the trans configuration. Research indicates that eating trans fats is associated with an increased risk for heart disease.