CRAZED ABOUT COCONUT OILTHE CATABOLIC PROCESS

What is Coconut Oil?Coconut oil is a saturated medium-chain fatty acid that has become increasingly popular in the United States due to the hype over its health benefits. Like any other saturated fat, this oil is solid at room temperature. However coconut oil has a structure composed of primarily medium-chain fatty acids, which contain 8-12 carbon atoms. Although coconut oil is a saturated fat, it does not contain trans fat or cholesterol, making it a better choice than trans fat-containing shortenings.8 There are two types of coconut oils, virgin and refined. Virgin coconut oil is high in lauric acid (C12:0), which is used for a variety of treatments including viral infections, the common cold, fever blisters, cold sores, and intestinal infections, as well as working to decrease total cholesterol:HDL-C.8.9.10. Virgin coconut oil is a healthier choice because it is produced by wet processing, rather than dry processing.11 Wet processing does not use heating or chemical refining treatments, contrary to the refined coconut oil process.11 Virgin coconut oil is obtained from fresh mature coconut kernels and has been found to have higher total phenolic content, and higher antioxidant activity than refined coconut oils.11 Some common beliefs about coconut oil include that it speeds up metabolism, provides energy, and is associated with lower risks of cardiovascular disease. Although these beliefs have not all been scientifically proven, it has been scientifically proven that the medium-chain fatty acids present in coconut oil metabolize through the body quicker and generate ATP more efficiently, when compared to long-chain fatty acids present in other fats such as butter and shortening.

How is Butter Different?Butter is made up of a combination of long-chain, medium-chain, and small-chain fatty acids, but consists primarily of long chain fatty acids. As a result, butter is absorbed differently within the small intestine than fats, like coconut oil, that are composed primarily of medium-chain fatty acids. Long-chain fatty acids require bile salts from the pancreas in order to become emulsified and further broken down for absorption. The long-chain fatty acids must combine with bile salts, monoglycerides, fatty acids, phospholipids, and cholesterol to form hydrophilic micelles.15 Once the micelles are formed, they are readily absorbed into the enterocytes. Within the enterocytes, the micelles are broken down and reassembled into long-chain fatty acids, which are then enveloped by lipoproteins to form chylomicrons. Finally, the chylomicrons can transport the long-chain fatty acids to the liver via the lymphatic system.15 This transport pathway is less efficient than that of medium-chain fatty acids because a chylomicron travel throughout the body and through the heart prior to making its way to the liver.2

Once the long-chain fatty acids reach the liver and enter the outer mitochondrial membrane of the hepatic cells, the carnitine shuttle is required in order to move the long-chain fatty acid acyl-CoAs from the intermembrane space into the matrix of the mitochondria. In the carnitine shuttle, the CPT I enzyme binds a carnitine molecule to a long-chain fatty acyl-CoA so it can be transported across the inner membrane of the mitochondrial matrix. Once inside the matrix, the long-chain fatty acyl-CoA will release the carnitine molecule using the CPT II enzyme and bind with an acyl-CoA molecule. The long-chain fatty acyl-CoA can then undergo beta-oxidation to produce energy.16

Coconut Oil Uses:12

Stir it in your coffee Sunburn careMelt it over potatoes or butternut squash Tanning oilStir it in your oatmeal Massage oil Sauté or grill with it Elbow rubSkin moisturizer Homemade toothpasteUse as makeup remover Wound careFacial/body scrub Thyroid supporterShaving lotion Aromatherapy Homemade deodorant Static reducerLip balm Overnight hair conditionerStretch mark preventative during pregnancy Salad dressingSubstitute it for butter by spreading over whole wheat toast Popcorn topping

containing less than 14 carbons have a faster stomach-emptying rate than the longer chains and a higher satiety rate, which leads to a reduced energy intake.1 Primary lipid digestion occurs in the small intestine where pancreatic lipases continue to break down the fatty acids. Unlike long-chain fatty acids, medium-chain fatty acids do not require bile salts for digestion. Therefore, the broken-down medium-chain fatty acids are absorbed directly into the hepatic portal vein and there are transported quickly, albumin-bound, to the liver.2 This differs from long-chain fatty acids, which require bile salts to esterify the fatty acids and repackage them into chylomicrons.3 The chylomicrons, also known as very-low density lipoproteins (VLDLs), carry the breakdown products of the long-chain fatty acids through the entire lymphatic system, which passes through the heart and adipose tissue prior to making its way to the liver. Consequently, the digestion, absorption, and transportation of long-chain fatty acids is much more inefficient than that of medium-chain fatty acids.

The direct transport of the medium-chain fatty acid constituents to the liver allows the fatty acids to be used in a multitude of processes. The first possible process is called beta-oxidation, which is the process of breaking down fatty acid acyl-CoAs into acetyl-CoA molecules to be used in the citric acid cycle for the production of energy. The medium-chain fatty acids can freely penetrate the mitochondrial membrane, whereas the long-chain fatty acids are required to use the carnitine shuttle system to enter the mitochondria. The implication of this factor is that there is a limit as to how many long-chain fatty acids can enter the mitochondria for beta-oxidation if there is a shortage in any of the shuttle components. Theses components includes the carnitine palmityl transferase (CPT) I and II. Once these fatty acid acyl-CoAs are in the matrix of the mitochondria, they are oxidized to produce acetyl-CoA molecules that are used to produce ATP.2 Medium-chain fatty acids work similarly in beta-oxidation as carbohydrates do in glycolysis to produce immediate ATP, whereas long-chain fatty acids are not as efficiently used because of the required shuttle system. The second possible process is called peroxisomal beta-oxidation. This oxidative process occurs in peroxisomes and is a backup system if mitochondrial beta-oxidation is overloaded.4 In this system, fatty acid chains are gradually shortened and sent through the beta-oxidation cycle to eventually produce ATP, though at a much more inefficient rate than mitochondrial beta-oxidation.5 This system is preferential towards medium-chain fatty acids than long-chain fatty acids. It is even suggested that this fat-catabolic pathway may increase thermogenesis and therefore increase total energy expenditure.2

The final possible process is known as omega-oxidation. This process occurs as a backup for beta-oxidation when the pathways are blocked.6 It occurs in the microsomes and in the cytosol of the hepatic cells and produces dicarboxylic acids, which are excreted in the urine.7 It has been found that fatty acid chains consisting of 10 and 12 carbon atoms have a higher affinity for omega-oxidation than any other chain length. Hence, medium-chain fatty acids have another backup system if beta-oxidation pathways are blocked, whereas long-chain fatty acids do not, and are therefore more likely to be stored as fat.2

Overall, since medium-chain fatty acids are more efficiently transported to the liver, they will be used first in the catabolism of fatty acids for energy. Furthermore, the three possible pathways of oxidation – mitochondrial beta-oxidation, peroxisomal beta-oxidation, and omega-oxidation – all have a higher affinity for medium-chain fatty acids. This means that medium-chain fatty acids will be more readily used than long-chain fatty acids. The implications of this are increased storage of long-chain fatty acids and any medium-chain fatty acids that are not needed for energy production. Since coconut oil is composed primarily of medium-chain fatty acids, it is more efficiently used for energy and less likely to be stored as fat compared to lipids containing primarily long-chain fatty acids.

Metabolism of Coconut Oil Coconut oil consists primarily of saturated medium-chain triglycerides, which are composed of 8-12 carbon atoms. Once ingested, a small amount of digestion begins in the mouth with the aid of lingual lipase. Digestion continues in the stomach with the aid of gastric lipase, which removes fatty acids from the fatty acid chains. These lipases are preferential in that they break down small- and medium-chain triglycerides before breaking down the longer chain triglycerides, which contain 14 or more carbon atoms. Fatty acid chains

Coconut Oil Effective in Treating Diabetes. CoconutOil.com. http://coconutoil.com/diabetes/. Accessed October 20, 2014.

Medium Chain Triglycerides. Triglycerides. http://triglycerides.me/triglyceride/medium-chain-triglycerides/. Accessed October 20, 2014.

Figure 1. Fatty Acid Composition of Coconut Oil and Butter17.18

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By: Alana Misiura Allison Foster Ivy Haines Alex Liddy