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TOPIC 5:
LIPIDS: ESSENTIAL
ENERGY-SUPPLYING
NUTRIENTS

What Are Lipids?
■ Lipids
– Diverse group of molecules that are insoluble in water

■ Fats
– The lipid content of diets and foods
■
–
–
–

Three types of lipids are found in foods and in body cells and tissues:
Triglycerides
Phospholipids
Sterols

Triglycerides
■ Triglycerides (also called triacylglycerols) contain:
– Three fatty acid molecules
– One glycerol molecule
■ Fatty acids are classified by the type of fatty acids attached to the glycerol
backbone
...


■ Monounsaturated fatty acids (MUFAs) : Fatty acids that have two carbons in the
chain bound to each other with one double bond
...


Triglycerides: Saturation

Triglycerides: Shape
■ Level of saturation affects fatty acid
shape

■ Saturated fatty acids:
-

form straight, rigid chains, packed
tightly together
...
)
■ Unsaturated fatty acids:
-

have kinked fatty acids at double bond and
do not pack together tightly

-

liquid at room temperature

■ Hydrogen atoms can be arranged in different
positions at the point of unsaturation:
– Cis: same side of the carbon chain
– Trans: opposite sides of the chain

Triglycerides
■
–
–
–
–

Hydrogenation: hydrogen atoms are added to unsaturated fatty acids
Make oils more solid and more saturated
Create trans fatty acids
Helps food reduce oxidation and resist rancidity
Increase risk of cardiovascular disease

Triglycerides (cont
...
)

Triglycerides (cont
...

■ Manufactured in our bodies (not
required)

Sterols
■ Sterols contain multiple rings of
carbon atoms

■ Cholesterol is found in animal-based
foods as cholesterol esters
...
)
■ Chylomicrons are transported out of the enterocyte, then:
– Travel through the lymphatic system
– Are transferred to the bloodstream through the thoracic duct
■ Short- and medium-chain fatty acids are absorbed more quickly since they are not
arranged into chylomicrons

Absorption of Fats (cont
...
6−1
...
When this occurs, the region of the brain depending on
that artery for oxygen and nutrients cannot function
...


Cardiovascular Disease
■ Coronary heart disease: occurs when blood vessels supplying the heart (the
coronary arteries) become blocked or constricted; such blockage reduces the flow of
blood and the oxygen and nutrients it carries to the heart
...


Cardiovascular Disease
■ Hypertension : is a condition that may not cause any symptoms, but it increases your
risk for a heart attack or stroke
...


Cardiovascular Disease
■ Atherosclerosis: A disease in which arterial walls accumulate deposits of lipids and
scar tissue, which build up to a point at which they impair blood flow

Risk factors Cardiovascular Disease
■
–
–
–
–
–
–

Risk factors for cardiovascular disease:
Being overweight
Physical inactivity
Smoking
Type 2 diabetes
Inflammation
Abnormal blood lipids

The Role of Blood Lipids in CVD
■ lipids are transported in the blood by lipoproteins made up of a lipid center and a
protein outer coat
...

■ The names of lipoproteins reflect their proportion of lipid
...
, very-low-density lipoproteins (VLDLs) have a high ratio of lipid to protein

The Role of Blood Lipids in CVD
■
–
–
–
–

Blood lipids include:
Chylomicrons—present only after a meal
Very-low-density lipoproteins (VLDL)
Low-density lipoproteins (LDL)
High-density lipoproteins (HDL)

The Role of Blood Lipids in CVD
■ High levels of circulating low-density lipoproteins, or LDLs, increase total blood
cholesterol concentrations and the formation of plaque on arterial walls, leading to
an increased risk for cardiovascular disease
...
”
■ High levels of circulating high-density lipoproteins, or HDLs, reduce our blood
cholesterol levels and our risk for cardio- vascular disease
...
”

The Role of Blood Lipids in CVD
■ Dietary fats increase blood lipids
■ Saturated and trans fatty acids increase the blood’s level of the lipids associated
with cardiovascular disease namely, total blood cholesterol and the cholesterol
found in VLDLs and LDLs
...


Blood Lipid Levels:
■ The target lipid values are as follows:
-

Total cholesterol (mg/dl): <200 mg/dl

-

LDL-cholesterol (mg/dl): <130 mg/dl

-

HDL-cholesterol (mg/dl): >40 mg/dl

-

Triglycerides (mg/dl): <150 mg/dl

Lifestyle Changes Can Prevent or
Reduce Cardiovascular Disease
■
–
–
–

Lifestyle changes can prevent or reduce cardiovascular heart disease
Follow DRIs for total fat, saturated fat and trans fat
Increase omega-3 fatty acids
Increase intake of whole grains, fruits and vegetables; dietary fiber: 20−30 grams
per day
– Consume RDA of vitamins B6, B12, and folate
– Select and prepare foods with less salt
– Eat smaller meals and snacks

Lifestyle Changes Can Prevent or
Reduce Cardiovascular Disease
■
–
–
–
–
–
–

Lifestyle changes can prevent or reduce cardiovascular heart disease
Add plant sterols to your diet
Maintain normal blood glucose level
Maintain a healthy body weight
Maintain an active lifestyle
No more than 2 alcoholic beverages per day for men and 1 drink per day for women
If you smoke, stop

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