Download Lecture 8

Why do we need Lipids?
Lecture 8:
Lipids, Part 2
Vital to many body functions
– Cell membrane structure
– Nerve cell transmissions
– Protection of internal organs
– Insulation to retain body heat
Nutrition 150
Shallin Busch, Ph.D.
Lipids as Energy
• Lipids are energy dense (9 kcal/g)
• Much of the energy used during rest
comes from fat
• Fat is used for energy during
exercise, especially after glycogen is
depleted
• Fat is also used for energy storage.
Lipids and Nutrients
• Vitamins A, D, E, and K are soluble in
fat
• Fat is required for their transport
Essential Fatty Acids
Linolenic acid, an omega-3 fatty acid
Omega carbon
Two necessary fatty acids that cannot be
synthesized in the body and must be
obtained in the diet
– Omega-3 fatty acid
• Found in vegetables, fish and fish oils
• Important for growth and development, esp. in
the eyes and brain
Acid end
Methyl end
Linoleic acid, an omega-6 fatty acid
Omega carbon
• Prevention and treatment of heart disease
– Omega-6 fatty acid
• Found in vegetable and nut oils
Essential Fatty Acids
Used to make eicosanoids: biologically
active derivatives of the essential
fatty acids.
Eicosanoids regulate:
– Blood pressure
– Blood clotting
– Immune response to injury and infection
– Reduce inflammation
Acid end
Methyl end
Table 5-2
Page 161
How much lipids to consume?
Type of Lipid is
VERY Important
• The Acceptable Macronutrient Distribution
Range (AMDR) for fat: 20-35% of calories
(65g based on 2000 cal diet)
• Saturated fat should be no more than
7% of total calories (20g)
• Athletes and highly active people may need
more energy from carbohydrates and can
reduce their fat intake to 20-25% of total
calories.
Food Sources of Fat
Visible fats
– Fats we knowingly add to foods
– Butter, cream, mayonnaise, dressings
Invisible fats
– Fats hidden in foods
– Naturally occurring or added during
processing
• Trans fatty acids should be reduced
to the absolute minimum
• Most fat in our diets should be from
monounsaturated fats (eg., olive oil)
Saturated Fats
• Mostly from animal fats, but also
from some vegetables (coconut and
palm) and some hydrogenated fats
• Avoid by eating fat-free dairy
products; poultry and fish instead of
red meats; using non-hydrogenated or
unsaturated cooking oils
Saturated Fats in the U.S. Diet
Diets high in saturated fats
Milk, yogurt, and cheese 20%
Other 2%
Eggs 2% Nuts and legumes 2%
– Decrease the removal of LDLs from
the blood
– Contribute to the formation of
plaques that can block arteries
– Increase triglyceride levels
(chylomicrons and VLDLs)
Added fats and oils 34%
Meat, poultry, and fish 40%
Fruits, grains, and vegetables are insignificant sources, unless
saturated fats are intentionally added to them during preparation.
Comparison of Dietary Fats
Most fats are a mixture of saturated, monounsaturated, and polyunsaturated fatty acids.
Animal fats and the tropical oils of coconut and palm are mostly saturated.
Coconut oil
Butter
• Can raise LDL cholesterol as much as
saturated fat
Beef tallow
Palm oil
Lard
Some vegetable oils, such as olive and canola, are rich in monounsaturated fatty acids.
Olive oil
Canola oil
Peanut oil
Many vegetable oils are rich in polyunsaturated fatty acids.
Safflower oil
Sunflower oil
Corn oil
Soybean oil
Cottonseed oil
Trans Fats
Key:
Saturated fats
Polyunsaturated,
omega-6 fats
Monounsaturated fats
Polyunsaturated,
omega-3 fats
• In “stick” margarines, baked goods,
fried foods, snack foods, fast foods,
non-diary creamer
Cholesterol
Table H5-1
Page 177
• Can raise LDL cholesterol, but less than
saturated or trans fats
• Try to limit, especially if at risk for or
suffering from heart disease (300mg/day)
• Only in foods from animals
• Most cholesterol
in body is synthesized
by the liver and does
not come from the diet
Cholesterol in Selected Foods
CHOLESTEROL - Only foods of animal
origin contain cholesterol. Consequently
grains, vegetables, legumes, and fruits
provide no cholesterol.
Daily
Value
Key:
Milk and milk products
Meats
Miscellaneous
Cardiovascular Disease
• Dysfunction of the heart or blood
vessels
• Can result in heart attack or stroke
• Leading cause of death in US
• The type of fat in our diet can
contribute to or protect against
cardiovascular disease.
Cardiovascular Disease
Risk factors include:
– Being overweight
– Physical inactivity
– Smoking
– High blood pressure
– Diabetes
– Diets high in saturated and trans
fats
Atherosclerosis
A type of artery disease characterized by
plaques (accumulations of lipid-containing
materials) on the inner walls of the arteries.
Cross-section of (a) a normal artery and (b) a partially
blocked artery.
Cardiovascular Disease
• Can fat intake protect against heart
disease? YES!
• Diets high in omega-3 fatty acids
(along with moderate exercise) can
increase HDL “good” cholesterol
levels.