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What is Fat and Why Are Trans Fats so Bad?
October 10, 2008
Today we are constantly bombarded with an unceasing barrage of images that portray the idea that thin is beautiful and healthy. Fat has become a vague adjective that is subject only to the user’s perception of self and others. The idea of gaining weight for most is seen as a negative consequence of improper diet and living, which should be immediately reversed. Often people who are overweight are perceived as unhappy, lazy individuals with bad coping mechanisms and complete lack of control. When people walk into convenience stores or look at a magazine more times than not they are bound to see the new weight loss drug, fad diet, or shiny equipment that promises to help shed those unwanted pounds. But what is fat? Why do we have it, if all it causes is grief? And why is it so hard to get rid of?
What is a fat and is it healthy?
Fats are classified in biology as lipids, which are molecules that are insoluble in water because of their molecular structure. Fats themselves are large molecules that are assembled from two kinds of smaller molecules: a glycerol (an –OH group with 3 carbons) and fatty acids chains (usually a 16 or 18 carbon chain attached to a carboxyl (C=O) group) giving fats their hydrophobic (Greek: water fearing) tendency. It is because of the nonpolar characteristics created by the hydrocarbon chain that water and fats, such as oil, do not mix. When a fat is made, 3 fatty acid molecules join to each glycerol by an ester linkage, which is a bond formed between the carboxyl group of the fatty acid and the hydroxyl group of the glycerol forming what can also be called a triacylglycerol. This is why fats are sometimes called triglycerides on food labels.
The term fat has received such a negative connotation amongst people living in developed countries because it is believed to cause unwanted weight gain and a poor body image, leading people to wonder if there is any reason relating to good health that a person might need fat. However, it must be understood that the major function of fat is energy storage. Fat serves as a long-term energy store that can be burned, similar to how gasoline is used to power cars. Whenever the demands of the body exceed its stores of readily available energy, such as sugars (carbohydrates), the body uses its secondary energy source: fat. The fat stores are like a bank in which fat is deposited and withdrawn according to the body’s needs, hence why weight can fluctuate with an increase or decrease in physical demand. The consumption of fats was vital throughout human development especially in instances when food was not easily attained on a daily basis.
How many types of fats are there? And where can I find them?
The length of the carbon chain, the number of single or double bonds, and the specific locations of those bonds along the carbon chain in the fatty acid molecule create the variety of fats within the biological world (Campbell and Reece, 2005). Fatty acids usually vary between 14 and 20 carbons in length. The two major divisions of fats are termed unsaturated and saturated fats. Saturated fats, usually found in animal fat, have no double bonds along the carbon chain. If just one of the carbons in the fatty acid chain, is double bonded, meaning there isn’t a hydrogen on both sides of the carbon, then the term unsaturated fat is applied. Because of the formation of a double bond in unsaturated fats, “kinks” are produced along the fatty acid chain that make the structure look bent. The more kinks a fatty acid structure has, the harder less effectively the chains can be packed together. These characteristics are the reason why saturated animal fats are usually solid at room temperature, while unsaturated fats with many double bonds are liquid at room temperature and described as oils (Karp, 2008).
Unsaturated fats can be subdivided into various groups, three of which are monounsaturated fat, polyunsaturated fat, and trans fat.
Monounsaturated fats are fats that only have one double bond along the carbon chain, while polyunsaturated fats have two or more. Polyunsaturated and monounsaturated fats are “found mainly in many fish, nuts, seeds and oils from plants. Some examples of food that contain these fats include salmon, trout, herring, avocados, olives, walnuts and liquid vegetable oils such as soybean, corn, canola, olive and sunflower.”
To understand trans fats, one must again understand fatty acid structure. Unsaturated fats can be come in two orientations: “cis” and “trans”. The cis form, which is more common than the trans form, simply means that the hydrogens that are connected to the double-bonded carbons are both on the same side of the chain. The trans term means that the hydrogens face each other on opposite sides of the fatty acid chain (http://www.americanheart.org/presenter.jhtml?identifier=532 ).
So what are trans fats exactly and where do they come from?
Trans fatty acids are normally found in small amounts in a variety of animal products such as beef, pork, lamb, and the butterfat in butter and milk. However, the trans fats that most people are familiar with are formed during the process known as hydrogenation, which is used to make things such as margarine, shortening, and cooking oils. In hydrogenation hydrogen atoms are added to a molecule. “When unsaturated fatty acids are hydrogenated, some of the hydrogen atoms are added on opposite sides of the molecule to the already attached hydrogen.” This addition causes the cis double bonds to convert to trans double bonds, making the fatty acid saturated. The foods made with these trans fatty acids are a major source of trans fats in the American diet with partially hydrogenated vegetable oils providing about three-fourths of the trans fatty acids in an American diet. The major commercial reason for making trans fats is to extend the shelf life of certain products and as a cheaper alternative to the use of animal fats. However, the consequences of such actions are profound.
Are trans fats that bad? Why?
Multiple clinical studies have shown that the more trans fats a person consumes, the higher their potential for a myriad of heart-related problems. Currently, scientists are trying to understand exactly why this happens, but the most prevalent theory is that, the enzymes that are used to breakdown fats into energy are better matched for fats in the cis form. Thus, trans fats remain in the blood for much longer durations making it more likely for fats to clog arteries with plaque. In other words, the human body is thought to burn cis fats more effectively than trans fats preventing future buildup problems. Furthermore, scientists have proven that trans fatty acids and saturated fats are shown to raise the amount of LDL (low density lipoprotein, also known as bad cholesterol). However, not only do trans fatty acids raise LDL cholesterol levels more than saturated fats, but they also lower HDL (high density lipoprotein, also known as good cholesterol) thereby increasing the risk of heart disease and diabetes (http://www.americanheart.org/presenter.jhtml?identifier=532 ).
In the case of diabetes, a meta-analysis was performed that found, “in a groups of people in whom insulin sensitivity is of great concern, trans fatty acids exacerbated marker of the diabetic state…[However,] the literature on trans fatty acids, insulin resistance, and type 2 diabetes is not only conflicting...[but] limited in scope. The findings of this review suggest that high intakes of trans fatty acids in young, healthy, lean women and men have no significant effect on insulin sensitivity. In contrast, being overweight, having type 2 diabetes, and consuming higher amounts of trans fatty acids could cause or exacerbate insulin resistance (Odegaard & Pereira, 2006)”.
In another study done on the relationship between coronary artery disease and the presence of trans fatty acids in adipose tissue. “After adjustment for hypertension, smoking, triglyceride, and adipose tissue polyunsaturated fatty acids, levels of total trans fatty acids were associated with an increase risk of coronary artery disease.” The higher risk was partially attributed to the increase in LDL that was directly caused by the trans fats. However, “the exact mechanisms of the adverse effects of [trans fatty acids] are not yet established…(Ghahremanpour & Firoozrai & Darabi & Zavarei & Mohebbi, 2008)
What is being done about trans fats?
The problems associated with trans fats have become such an issue that public health mandates have been taken in order to decrease access to trans fats in several developed nations. Trans fats are considered by most to be the worst source of fat to consume because of the extremely adverse repercussions of its consumption to an individual’s health. It is because of such that states such as New York legally mandated the use of trans fats in restaurants to be below half a gram per serving by July 1, 2008. According to the New England Journal of Medicine “trans fats make up 2.6% of the American’s daily calorie intake, ...[equating to about] 6 grams daily for a person consuming 2000 calories per day.” In response to the evidence against the use of trans fats, “manufacturers such as Frito-Lay, Kraft, and Campbell’s reformulated popular brand chips, cookies, and crackers.” Walter Fehr, a plant breeder and geneticist of Iowa Sate had spent decades trying to and succeeding in the development of an ultra-low-linolenic soybean strain. He stated that “food companies showed no interest in his beans until the FDA announced that it would require trans fat labeling. Now there’s a market for as much low-linolenic soybean oil as processors can produce…” (Okie, 2007)
Conclusions: Is there a good fat? And how safe is it to limit fats in a diet?
According to the American Heart Association, total fat intake should be limited to less than 25 to 35 percent of the total calories consumed per day. The AMA goes on to state that consumption of polyunsaturated and monounsaturated fats may help lower blood cholesterol level when used in place of trans fats and saturated fats. It is also suggests to keep trans fat intake below 1 percent of the total calories consumed. Meaning, in the typical diet of 2,000 calories per day, a person is to consume no more than 2 grams of trans fat. In the case of saturated fat, the American Heart Association states that “saturated fat is the main dietary cause of high cholesterol” thus, should be limited in the consumption of products that contain it (http://www.americanheart.org/presenter.jhtml?identifier=532) .
Thus, according to the research and literary data collected, the healthiest fats are monounsaturated and polyunsaturated trans fats. By keeping “total fat intake between 25 and 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids”, a person can receive the necessary amounts of “good” fats without causing themselves injury. Trans fats are definitively linked to future health problems and should be avoided. The idea of consuming fat may initially seem to be adverse to one’s health. However, all things must be taken in moderation. With proper diet and exercise, a person would find that fats are not the end all of a good figure or a moderate level of fitness. They are essential to a person’s body in order to maintain proper function and form.
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