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Victoria Maynard
HUN3230 Section 81944
Triglycerides and Cardiovascular Disease
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Lipids are organic structures found in all sorts of living things, including the human body.
Triglycerides, also known as triacylglycerol, are one of the most common lipids found in food. A
triglyceride is made up of a glycerol backbone and three fatty acid chains. The glycerol backbone
is an alcohol composed of three carbon atoms. Attached to each carbon atom on the glycerol
backbone are the chains of carbon acids, the fatty acids. The level of saturation, length, and
shape of the chain all help classify triglycerides. If there are no double bonds and each carbon is
saturated with hydrogen’s it is classified as a saturated fatty acid. Butter is a prime example of a
saturated fatty acid. If there is a single double bond it is a monounsaturated fatty acid and more
than one double bond makes it a polyunsaturated fatty acid. Salmon, cashews, and olive oil are
high in monounsaturated fatty acids while tuna, safflower oil, and walnuts are high in
polyunsaturated fatty acids. Along with the level of saturation, the length of the fatty acid chain
varies. Fatty acids are categorized into three lengths: short (>6 carbons), medium (6-12 carbons),
and long (14< carbons). Shape also affects fatty acids. Saturated fatty acids are able to stack
together tightly while unsaturated fatty acids cannot because of the double bonds. Unsaturated
fatty acids can occur in cis or trans shape. Cis and trans describe the positioning of the hydrogen
atoms around the carbon double bond when discussing lipids. If the hydrogen is on the same side
it is cis, if it is on the opposite side it is trans. Cis fatty acids are typically found in nature while a
majority of trans fatty acids are commercially produced. One process where hydrogen is added to
fatty acids to break double bonds is hydrogenation. If only some of the double bonds are broken
the fat produced is called partially hydrogenated. An example of partially hydrogenated fatty
acid is palm kern oil. The placement of double bonds and the length of the fatty acid chain both
determine the function of the fatty acid in the body.1(174-178)
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Because triglycerides are not soluble in water bile form the gallbladder and digestive
enzymes from the pancreas aid in digestion. Little triglyceride digestion occurs in the mouth, but
lingual lipase secreted by tongue cells mixes with saliva to digest some triglycerides. From the
mouth triglycerides travel to the stomach where they are mixed and broken down into smaller
pieces. Gastric lipase also digests some triglycerides in the stomach. From the stomach
triglycerides travel to the small intestine. The small intestine has the capacity to digest a large
amount of triglycerides and although the process of digestion actually begins in the mouth and
stomach a majority of triglyceride digestion takes place in the lumen of the small intestine.2 The
liver produces bile, which is stored in the gallbladder. When triglycerides enter the small
intestine bile gets released from the gallbladder by CCK and breaks them into smaller pieces.
The pancreas produces lipid-digesting enzymes, pancreatic lipase and colipase, which get
released into the small intestine to break triglycerides down to monoglycerides and fatty acids.
Micelles then take the end products of lipid digestion and transport them to the enterocytes of the
small intestine. Components from micelles reform triglycerides within the enterocyte and
repackage them as chylomicrons for transport into the lymphatic system. Short and medium
chain fatty acids do not have to be reformed back into triglycerides and repackaged as
chylomicrons, they can travel into the blood stream bound to phospholipids or transport proteins.
Triglycerides within chylomicrons are released throughout the body with the help of lipoprotein
lipase, which is found on the outside of cells. When chylomicrons come in contact with cells,
lipoprotein lipase breaks apart triglycerides in the core of chylomicrons and allows individual
fatty acids to move into the cell. Chylomicrons fill up with cholesterol, phospholipid, and protein
as body cells are taking up the fatty acids. What is left of the chylomicron is the chylomicron
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remnant, which is removed from the blood by the liver. The liver then recycles the contents of
the chylomicron remnants. 1(183-185)
Triglycerides are transported by the chylomicron to cells in the body for energy.
Triglycerides participate in key metabolic functions such as energy storage, thermal insulation
and as deposit for essential and non-essential fatty acids. Triglycerides are major fuel sources
when at rest and during physical activity. The exact amount of energy coming from triglycerides
during rest and physical activity will depend on how much fat is in your diet. Essential fatty
acids are important in the prevention of DNA damage, fighting infection, and fetal growth.
Triglycerides also provide protection to the body by keeping it healthy and functioning properly.
Adipose tissue, the primary spot where energy is stored, cushions to body from injuries and fat
under the skin acts as insulation to help retain body heat. The good flavors and textures of foods
are contributed by fats and fats make you feel full.1(189)
Triglyceride has long been the lipid measure in the evaluation of cardiovascular risk.
Cardiovascular disease also called heart disease includes numerous problems, many of which are
related to a process called atherosclerosis.3 Atherosclerosis is a condition that develops when
plaque builds up in the walls of the arteries. This buildup narrows the arteries, making it harder
for blood to flow through. High triglycerides may contribute to hardening of the arteries or
atherosclerosis, which increases the risk of heart disease.3 High triglycerides are often a sign of
other conditions that increase the risk of heart disease and stroke as well, including obesity.
Evidence from prospective studies of triglyceride association with cardiovascular disease
supports a stronger link with cardiovascular disease risk in people with lower levels of HDL and
LDL and that have type 2 diabetes.4 Around 600,000 people die of heart disease in the United
States every year.5
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The American Dietetic Association and the Dietitians of Canada state that dietary fat for
the adult population should provide 20% to 35% of energy, emphasize a reduction in saturated
fatty acids and trans fatty acids, and an increase in n-3 polyunsaturated fatty acids.6 A diet high
in fruits and vegetables, whole grains, legumes, nuts, lean protein, and fish will help achieve the
dietary recommendations.6 The Dietary Reference Intake (DRI) report on macronutrients
recommended that saturated fatty acid and trans fatty acid be as low as possible. Consuming a
diet filled with essential nutrients is important to focus on while trying to decrease the intake of
saturated and trans fatty acids.7 The American Heart Association’s (AHA) Diet and Lifestyle
Recommendations recommended that saturated fatty acid intake be 7% of calories, and that trans
fatty acids be 1% of calories.8 Recommendations can be given by dieticians in order to help
clients.
Dieticians play a big role in the risk for cardiovascular disease related to food intake and
lifestyle choices. For clients that are overweight or obese losing weight can help lower
triglycerides. Cutting back on calories, limiting the amount of cholesterol in your diet, and
choosing healthier fats are all way to help lower triglycerides. It is the role of dieticians to make
sure clients understand food labels and rules for food labeling. For example, in the United States,
if a food contains less than 0.5 grams of trans fat a serving, it can be labeled trans-fat-free.3
Educating clients will better help them shop and buy food on their own. Physical activity along
with monitoring eating will help lower triglycerides. Physical activity not only lowers
triglycerides, it also improves HDL.
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Reference 1
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References
1. Thompson J, Monroe M, Vaughn L. Lipids: Essential Energy Supplying Nutrients. In:
Lindelof S, ed. The Science of Nutrition. Pearson; 2014: 174-189.
2. Gropper S, Smith J. Lipids. In: Williams P, ed. Advanced Nutrition and Human
Metabolism. Belmont, CA: Yolanda Cossio; 2013:146-147.
3. Mayo Clinic. Triglycerides: Why do they matter?. http://www.mayoclinic.com/health/
triglycerides. Published September 28,2012. Accessed October 3,2013.
4. Criqui MH, Heiss G, Cohn R, Cowan LD, Suchindran CM, Bangdiwala S, Kritchevsky S,
Jacobs DR Jr., O'Grady HK, Davis CE. Plasma triglyceride level and mortality from
coronary heart disease. N Engl J Med. 1993; 328: 1220–1225.
5. Kochanek KD, Xu JQ, Murphy SL, Miniño AM, Kung HC. Deaths: final data for
2009.
[PDF-2M] National vital statistics reports. 2011;60(3).
6. Kris-Etherton P, Innis S. Position of the American dietetic association and dietitians of
Canada: Dietary fatty acids. Journal Of The American Dietetic Association [serial
online]. n.d.;107(9):1599-1611. Available from: Science Citation Index, Ipswich, MA.
Accessed October 3, 2013.
7. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat,
Fatty acids, Cholesterol, Protein and Amino Acids. Washington, DC: National
Academies Press; 2002.
8. Lichtenstein AH, Appel LJ, Brands M, Carnethon M, Daniels S, Franch HA, Franklin B,
Kris-Etherton P, Harris WS, Howard B, Karanja N, Lefevre M, Rudel L, Sacks F, Van
Horn L, Winston M, Wylie-Rosett J. American Heart Association Nutrition Committee,
Diet and Lifestyle Recommendations Revision 2006: A Scientific Statement from the
American Heart Association Nutrition Committee. Circulation. 2006; 114:82-96.