Mayo Clinic Staff. ‘‘Traveler’s Diarrhea.’’ MayoClinic.com,
June 15, 2005.http://www.mayoclinic.com/health/
travelers-diarrhea/DS00318
University of Texas Houston, Ericsson, ed. ‘‘Traveler’s
Diarrhea.’’ BC Decker Inc., 2007 (CD-ROM)
Tish Davidson, A.M.Triglycerides
Definition
Triglycerides are a form of fat, consisting of three
molecules (‘‘tri’’) of a fatty acid combined with one
molecule of the alcohol glycerol. Triglycerides serve as
the backbone of many types of lipids (fats). Triglycer-
ides are produced by the liver as well as are ingested as
part of the diet. Fats in foods are digested and changed
to triglycerides.
Purpose
Triglycerides have several purposes in physiol-
ogy. Triglycerides travel through the circulatory sys-
tem and are either utilized immediately or are stored in
adipose tissue, thereby serving as the most abundant
form of stored energy in the body. Triglycerides can
serve as this important storage medium because of
their hydrophobicity, which allows them to be stored
as droplets, without contact withwatermolecules.
Often a typical human body may contain several
months of fuel stored in the form of triglycerides.
When physiological conditions dictate the need to
use the triglycerides, hormones or a neurotransmitter
signal their release. This release may be in response to
exercise, stress, or fasting. An enzyme called lipase
breaks down the triglyceride molecule into a glycerol
molecule and three fatty acids before release from the
adipose tissue. These breakdown products are trans-
ported within the circulatory system to the tissues that
need them for energy.
In addition to serving as a source of energy, tri-
glycerides carry the fat-soluble vitamins(including
vitamin K, an important nutrient in normal blood
coagulation). Triglycerides also provide thermal insu-
lation and contribute to the structure of membranes
by the formation of a lipid bilayer.
Triglycerides combine with a bloodproteinto
form chemicals referred to as high-density and low-
density lipoproteins. These lipoproteins contain cho-
lesterol, another substance related to fats.
Description
It is not yet clear whether high triglyceride levels
act as a predictor of the risk for heart disease and heart
attacks, especially in persons with normal levels of
cholesterol. Some health care professionals feel that
elevated triglycerides are a marker for other risk fac-
tors that do impact the risk of heart disease, that is,
high levels of triglycerides are usually associated with
low levels of high density lipoproteins, usually referred
to as the ‘‘good’’ cholesterol.
However, there are some indications that high
triglycerides may serve as a predictor for heart disease,
especially in women. In a study involving postmeno-
pausal women (aged 48 to 76 years old) conducted by a
research group from the Center for Clinical and Basic
Research in Ballerup, Denmark, it was found that
women who had an enlarged waist and elevated levels
of triglycerides had almost a five-fold increased risk of
fatal cardiovascular events compared to women with-
out those traits. The women at risk deposited fat cen-
trally in their intra-abdominal compartment, rather
than in their hips, thighs, and buttocks.
The mechanism of how triglycerides might affect
heart health is not fully known, but it appears that ele-
vated levels of triglycerides may allow increased blood clot
formation and may slow the natural breakdown of clots
after they have formed. However, high levels of triglycer-
ides may mean an increased risk of diabetes, and very high
levels of triglycerides may increase the risk of inflamma-
tion of the pancreas, resulting in pancreatitis.
Triglyceride levels are evaluated through blood
testing.A fatty meal that is high in triglycerides will
cause a short term increase in blood triglyceride levels.
Therefore, before testing, a person should refrain from
eating food for eight to ten hours before the test and not
drink alcohol for 24 hours before the test. Some medi-
cations may interfere with test results, and the health
care provider may request that the person cease taking
the medications before testing. For example, oralTriglyceride levelsNormal Less than 150 mg/dL
Borderline-high 150–199 mg/dL
High 200–499 mg/dL
Very high 500 mg/dL or aboveSOURCE: National Heart, Lung and Blood Institute, National
Institutes of Health, U.S. Department of Health and Human
Services(Illustration by GGS Information Services/Thomson Gale.)Triglycerides