Lipids and their Importance in our Diet Western Governors University

What are Lipids

Lipids are non-polar organic molecules made up primarily of a glycerol molecule attached to a fatty acid chain. A fatty acid chain consists of carbon atom backbone with several hydrogen bonds (figure 1).One example of a fatty acid is triglyceride. A triglyceride is composed of a glycerol molecule and three fatty acid chains or tails. Lipids or fatty acids such as a triglyceride are used for energy storage by the body and get stored in specialized cells called adipose cells. These cells are then stored together in what is called adipose tissue (figure 2). How energy is produced Fats are broken down in a process called oxidation and the energy released during this process is retained in the form of adenosine triphosphate or ATP. The first step in lipid breakdown involves separating the glycerol from the fatty acid chain in a step called hydrolysis (“Lipid Catabolism”, n.d., para. 2). In the next step, the fatty acids are broken down into two carbon pieces called acetyl-CoA. Once the fatty acids chains are broken down into acetyl-CoA they can enter the kreb or citric acid cycle. This cycle, along with the electron transport chain cycle, turns each acetyl-CoA molecule into twelve ATP. This means that a single fatty acid chain consisting of sixteen carbons can be broken down into eight acetyl-CoA molecules which will each yield 12 ATP. In comparison, a single molecule of glucose only yields two acetyl-CoA molecules which makes only 24ATP. The high yield of ATP from lipids compared to the yield of ATP from glucose is what makes lipids an excellent choice for energy storage. Types of Fatty Acid There are two main types of fatty acids; saturated and unsaturated fatty acids. The main difference between the two types of fatty acids is the number of hydrogen atoms bonded to each carbon atom. This difference occurs when there is one or more double bonds among the carbon atoms. Saturated fats are fatty acids that have their carbon atom bonds 'saturated' with hydrogen atoms (figure 3). One property of saturated fatty acid is that it is solid at room temperature. One example of this is butter. Sources of saturated fats are usually from meats such as beef or chicken.

Unsaturated fats are fatty acids that have one or more double bonds between some of the carbons in the carbon chains (figure 4). This results in the fatty acid having fewer hydrogen atoms bonded to the carbons resulting in the carbon backbone of the fatty acid to be less saturated or 'unsaturated' with hydrogen atoms. One property of unsaturated fatty acids is that they are liquid at room temperature such as olive oil. Unsaturated fatty acids are also essential to our diet since it is the one type of fat that our bodies can not produce. This makes many unsaturated fatty acids 'essential' fats that we need in our diet. Sources of unsaturated fatty acids include different plant based oils such as olive oil, fish, and nuts. In comparison, our bodies can produce saturated fatty acids which makes it less desirable in our diets which means consuming to many saturated fats can lead to illness and disease such as clogged arteries, heart attacks and strokes (Dutchen, 2010). Importance of Fat Fat is one of the essential nutrients in a healthy diet and it is one of the three essential macronutrients needed by all living creatures (Colbin, 1997). Without fat our bodies would not function properly. Fats or fatty acids are at the core of every cell and allow our cells and the compartments within our cells to do specialized functions which makes us what we are. As mentioned, lipids or fats are essential to every cell, phospholipids are a type of lipid which forms the cell membrane around and within cells. These phospholipids makes it possible for several cellular activities to happen within a cell at one time since the phospholipid form bi-layer compartments in and around the cell (figure 5). Fatty acids, both saturated and unsaturated are essential to the human body. Fats store energy, provide warmth and insulate vital organs, act as messengers between cells and help start chemical reactions that help with the basic functions of our body (Dutchen, 2010). Not only cans fats be a major source of energy for our bodies but it is also essential in the daily activities of our cells and bodies. Fat is also essential for proper immune system and horomone production, and the use and storage of certain nutrients such as the fat soluble vitamins A, D, E,and K. Fats and Our Diet

We often hear that fat is the enemy and many people strive to eat fat free diets. While its true that a diet high in saturated fat is unhealthy and can lead to illness and diseases such as high cholesterol, clogged arteries, stroke, heart attacks and obesity; fat is not the enemy. Several fats, such as unsaturated fats are actually essential to the human body and cannot be made by our systems. This requires us to acquire these 'essential fats' through our diets. Deficiencies in essential fatty acids such as omega 3 and omega 6 can lead to a myriad of liver and kidney disorders, decreased immune function, depression, and dry skin (“Essential Fatty Acids”, 2010). Essentials fats are not only necessary component of our bodies to function properly, but they help combat the effects of high levels of unhealthy fats on our body. Essential fats also help reduce inflammation and disorders associated with joint pain and arthritis, as well as number of other diseases (“Essential Fatty Acids”, 2010). Fats, both saturated and unsaturated are also used in our bodies for cell processes, to make hormones and in the absorption of certain nutrients such as vitamins A, D, E, and K. Without fat in our diet we would be unable to absorb these nutrients and would soon find ourselves deficient which would lead to illness and disease. For example, vitamin D deficiencies cause and increased risk of Alzheimer, osteoporosis, depression and bone pain; while vitamin A deficiencies can lead to immune-deficiencies and night blindness (Bellows & Moore, 2012). While vitamin E deficiencies are quite rare, vitamin k deficiencies can be rather dangerous. Vitamin K helps with clotting and the creation of clotting factors. Without sufficient amounts of vitamin K individual can experience increased clotting times and bleeding (Bellows & Moore, 2012). To truly eat a healthy diet we much eat everything in moderation. To much of any one nutrient is unhealthy and this is true for fats as well. A diet low or free of fats is just as unhealthy as a diet high in fats and a nonfat diet can lead to illness and disease just a quickly as a high fat diet can. Fat free diets can also lead to weight gain and obesity. One reason a fat free diet is so unhealthy is that fats aid in the feelings of fullness and satiety. People who eat fat free diets often end up consuming more calories in the form of carbohydrates and proteins to curb their hunger (Colbin, 1997). This leads to our bodies

storing the extra calories as fat in our bodies which adds to weight gain. Another reason fat free diets are bad for you is that many fat free foods have an excess amount of carbohydrates, proteins and chemicals to make up for the lack of fat. The chemicals are not only bad for you but the excess carbohydrates and calories cause people to consume a larger amount of calories which are again turned to fat in the body. Taking into account all the processes which require fat to function; it is easy to see why fat is essential part of our diets and how a fat free diet is very detrimental to our systems.

References Bellows, L. & Moore, R. (2012) Fat Soluble Vitamins A, D, E, and K. Retrieved August 5, 2014, from http://www.ext.colostate.edu/pubs/foodnut/09315.html Colbin, A. (1997) Fat-free Food: A bad Idea. Retrieved August 4, 2014, from http://www.foodandhealing.com/articles/article-fatfreebad.htm Dutchen, S. (2010) What Do Fats Do in the Body. Retrieved August 4, 2014, from http://publications.nigms.nih.gov/insidelifescience/fats_do.html Essential Fatty Acids. (2010) Retrieved August 4, 2014, from http://www.pcrm.org/health/healthtopics/essential-fatty-acids Lipid Catabolism Summary. (n.d.). Retrieved August 4, 2014, from http://www.elmhurst.edu/~chm/vchembook/622overview.html [Untitled JPEG image of adipose cell and tissue]. Retrieved August 5, 2014, from http://medicineworld.org/stories/lead/12-2010/fat-cells-become-useful-stem-cells.html