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CRAZED ABOUT COCONUT OIL
THE CATABOLIC PROCESS
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
By:
Alana Misiura
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, mediumchain 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.
Allison Foster
Ivy Haines
Alex Liddy
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.
Medium Chain Triglycerides.
Triglycerides.
http://triglycerides.me/triglyceri
de/medium-chain-triglycerides/.
Accessed October 20, 2014.
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 acylCoAs 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 betaoxidation 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.
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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 betaoxidation to produce energy.16
Coconut Oil Effective in Treating Diabetes. CoconutOil.com. http://coconutoil.com/diabetes/. Accessed October 20, 2014.
Coconut Oil Uses:12
Stir it in your coffee
Melt it over potatoes or butternut squash
Stir it in your oatmeal
Sauté or grill with it
Skin moisturizer
Use as makeup remover
Facial/body scrub
Shaving lotion
Homemade deodorant
Lip balm
Stretch mark preventative during pregnancy
Substitute it for butter by spreading over whole wheat toast
Sunburn care
Tanning oil
Massage oil
Elbow rub
Homemade toothpaste
Wound care
Thyroid supporter
Aromatherapy
Static reducer
Overnight hair conditioner
Salad dressing
Popcorn topping
Figure 1. Fatty Acid Composition of Coconut Oil and Butter17.18