The purpose of this paper is to provide an overview of the different types of fatty acids. There are several classes of naturally occurring fatty acids. There are the saturated fatty acids, the monounsaturated fatty acids, the polyunsaturated fatty acids and the essential fatty acids. We will also discuss another type of fatty acid that is not naturally occurring, the trans-fatty acid.
Saturated fats are the simplest fatty acid. They come in different lengths. They are divided into two groups:
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Short-chain fatty acids remain in liquid form for longer periods of time and are partially soluble in water. They have a chain length from three to twelve carbons. Tropical oils such as coconut and palm oil are made up of short-chain fatty acids.
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Long-chain fatty acids are solid fats that have a melting point higher than body temperature, remain solid at room temperature and are insoluble in water (i.e. butter, cheese, and beef tallow). (Nutrition Educator Handbook, pg. 234)
The longer chain saturated fatty acids range from 14 to 24 carbons, and they are myristic acid (14 carbons), palmitic acid (16 carbons), stearic acid (18 carbons), arachidic acid (20 carbons), behenic acid (22 carbons), and lignoceric acid (24 carbons).
The term saturated in fats and oil terminology means "no double bonds".
The second and third class of fatty acids are the monounsaturated and polyunsaturated types. Structurally, the monounsaturated fatty acids have one (mono) double bond, while the polyunsaturated fatty acids have more than one.
Monounsaturated fatty acids are unsaturated fatty acids that remain liquid at room temperature. Monounsaturated fatty acids are found in 14, 16, 18, 22, and 24 carbon lengths, the most common being the 18-carbon monounsaturated oleic acid. The best known source of oleic acid in oil has been olive oil, although there are oils from foods such as avocado and nuts such as hazelnut that have inherently higher levels of oleic acid than olive oil. (Enig, 2005; p. 36) Other sources of oleic acid are almond, canola, walnut, and seed oils.
Studies suggest that diets with a higher proportion of monounsaturated fats in their diet have a lower incidence of heart disease and breast cancer. (Nutrition Educator Handbook, 2005: pg. 234)
The polyunsaturated fatty acids are usually found in 18, 20, and 22 carbon lengths. The most well-known are the omega-6 fatty acids — linoleic, gamma-lindenic, and arachidonic acids — and the omega‑3 fatty acids — alpha-linolenic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Thus, the polyunsaturated fats contain the two fatty acids that have been categorized as "essential", i.e. linoleic acid and alpha-linoleic acid.
These two fatty acids are considered essential because our bodies cannot manufacture them. They must be obtained from our diet. These are healthy fats our bodies require. Many people are deficient in these healthy fats because of society's phobia of fat. Much of our population are eating unhealthy fats while being deficient in these fats that are absolutely necessary for good health.
Polyunsaturated omega-3 fatty acids are found in flax, pumpkin seeds, walnuts, green leafy vegetables and cold‑water fish. More and more research is confirming the importance of the omega-3s and their ability to prevent heart disease. "The Nurse's Health Study in 1984 showed that women who consumed more omega-3s were about half as likely to die from a fatal heart attack." (Nutrition Education Handbook, 2005; p.235)
The polyunsaturated omega-6 fatty acids are found in safflower, sesame, sunflower, soy, canola, and corn oils, as well as meats and chicken.
Having a balance of both omega-3s and Omega-6s is considered important for achieving optimal health.
Fat is crucial to our survival. It is our greatest source of energy, it builds and maintains healthy cells, it insulates and protects our organs and tissues, it enables us to absorb our fat-soluble vitamins, it maintains our skin and hair, it is necessary for the production and quality of hormones, prostaglandins, cholesterol, and it is required for digestive function.
The crucial role fats play in our health and survival is undermined by the last class of fatty acids we will discuss, the trans-fatty acid.
These are the non-naturally-occurring fatty acids to which I referred at the beginning of this paper. They are synthetic mutations of fat created by the food industry to make foods last longer on the shelf. Trans fats occur in most processed food, such as commercial cakes, pies, crackers, bread, chips, snack foods, and salad dressings.
Trans-fatty acids are a type of fat molecule produced by a process called partial hydrogenation, which rearranges the hydrogen atoms in an unsaturated fatty acid to produce a fat that is solid at room temperature. This process changes the molecular structure of the unsaturated fatty acid from having their hydrogen atoms at the site of the double bond paired on the same side to having one of the hydrogen atoms in the pair moved to the other side of the chain. Thus, the word trans, meaning across.
This is a less expensive fat to use in the manufacturing of many foods. "Unfortunately, when these trans-fatty acids are incorporated into the cell membrane, they are missing the hydrogen pairs needed for chemical reactions to occur. The result is dysfunction and chaos on the cellular level." (Price, 2005; p. l)
Trans fats only cause harm. They disrupt and block normal and healthy metabolic function.
In conclusion, I want to reiterate that our bodies cannot survive without fat. Also, it must be understood that some fats are healthier than others. Not all fats are created equal.
A diet with a high proportion of saturated fat from animal sources (meat, butter, lard) has been found to be less healthy than a diet rich in plant-derived monounsaturated fat from, for example, olive oil. Also, it is now understood that the human body cannot function properly without the two essential polyunsaturated fatty acids — linoleic and alpha-linoleic. They are truly "essential to normal cell structure and body function. Both essential fatty acids function as components of nerve cells, cell membranes, and the hormone-like structures known as prostoglandins." (Murray, 1996: pg. 237)
Eating for health requires that we know what is healthy and what is not. Our understanding of the different classes of fats and fatty acids, and their benefits — or lack of benefits in the case of the trans fatty acids — will enable us to be more helpful to our future clients and ourselves.
Bibliography
Enig, Ph.D. Mary. Know Your Fats. Silver Springs: Bethesda Press, 2000.
Murray, N.D., Michael. Encyclopedia of Nutritional Supplements. New York: Three Rivers Press, 1996.
Nutrition Educator Handbook, Bauman College: 2005.
Price, Weston. "All About Trans Fats". The Weston A Price Foundation Wise Traditions. 2005. (a flier) |