406 Chapter 16
thereby constricting blood fl ow. Eventually
the fl ow of blood (and oxygen) to the heart
is interrupted, causing heart attack. Deprived
of vital oxygen in a section of the heart, the
heart tissue dies. If a plaque breaks loose and
is lodged in the brain, it may cut off blood
supply to a section of the brain, causing a
stroke. Therefore, it is desirable to control the
level of LDL - C in blood to preserve blood
fl ow.
High - density lipoproteins (HDL - C) con-
stitute a protective fraction of blood lipids.
They remove cholesterol from the blood-
stream, LDL - C, and walls of arteries. HDL - C
transports cholesterol back to the liver.
Triglycerides originate from dietary fats
and circulate in the bloodstream. They per-
form an important function by transporting
fat to the cells. However, excessive amounts
of blood triglyceride are involved in plaque
formation and are not healthy.
In general, elevated LDL - C in blood
(higher than 100 mg/dl) and a high level of
blood triglycerides (higher than 150 mg/dl)
are believed to have a positive correlation
with CVD. The HDL - C protects an individ-
ual from CVD. An optimum level of HDL is
higher than 60 mg/dl.
Although, these guidelines are still com-
monly used, some modifi cations are being
suggested. Westman (2009) has advocated “ a
change from dietary fat restriction (which
lowers LDL) to dietary carbohydrate restric-
tion (which lowers triglycerides and raises
HDL) ”.
The American Heart Association (AHA)
(Lichtenstein et al., 2006 ) has recommended
goals for CVD risk reduction:- Consume an overall healthy diet
- Aim for a healthy body weight (body - mass
index of 18.5 to 24.9 kg/m^2 ). - Aim for optimal levels of blood LDL - C
and HDL - C and triglycerides - Aim for normal blood pressure, which is
below 120 mm Hg, systolic, and below
80 mm Hg, diastolic. Pre - hypertension is
systolic 120 to 139 and diastolic 80 to
Food Lipids and
Cardiovascular Disease
By defi nition, cardiovascular disease (CVD)
includes diseases and injuries of the blood
vessels (arteries and veins) of the heart, entire
body and brain. Stroke, which involves ces-
sation of blood fl ow in the brain, is a form of
CVD. As the population ages, the incidence
of CVD and the corresponding fi nancial
impact continue to escalate. Research into
CVD has accelerated in the last 50 years, and
the studies have elucidated, to a degree, how
nutrition and genetics impact heart health.
Contribution of Food Lipids to Blood
Lipid Profi le
Fat plays a vital role in life as an important
source of energy as well as a depot of energy
storage. Fat is a concentrated source of
energy (8.79 kcal/g). It protects organs and
insulates the body from environmental tem-
perature effects, is a critical component of
cell membranes, assists in the regulation of
cellular traffi c, infl uences the action of
insulin, and is involved in the boy ’ s infl am-
mation status.
Cholesterol is a fraction of the dietary and
blood lipid profi le. It comes from dietary fat
but is predominantly synthesized in the liver.
Cholesterol is important in its role as a pre-
cursor of hormones (estrogen, testosterone)
and vitamin D.
Many studies have supported a positive
association between risk of CVD and ele-
vated blood cholesterol, some of its fractions,
and triglycerides. Blood lipid - protein
agglomerates (lipoproteins) are indicative of
the risk.
Low - density lipoproteins (LDL - C) carry
cholesterol from the liver to various parts of
the body, and the cells extract fat and choles-
terol for their needs. However, excessive
levels of LDL - C in the blood leads to depos-
its (plaques) of wax - like material in the walls
of coronary and other arteries. The plaques
result in narrowing of coronary arteries,