PHED 2015- Nutrition For Life 4e

1. Chapter 4 Lecture
Chapter 4:
Fats: Essential
Energy-Supplying
Nutrients
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2. Learning Objectives
1. Compare and contrast the three types of lipids
found in foods.
2. Discuss how the level of saturation of a fatty
acid affects its shape and the form it takes.
3. Explain the health benefits and dietary sources
of the essential fatty acids.
4. List five functions of fat.
5. Describe the steps involved in fat digestion,
absorption, and transport.
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3. Learning Objectives
6. Identify the dietary recommendations for intakes
of total fat, saturated fat, trans fats, and the
essential fatty acids.
7. Identify common food sources of less healthful
versus more healthful fats.
8. Summarize our current understanding of the
relationship between intake of dietary fats and
the development of cardiovascular disease and
cancer.
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4. What Are Fats?
• Fats are one type of a group of substances
called lipids.
• Other types of lipids are triglycerides,
phospholipids, and sterols.
• Lipids are distinguished by the fact that they are
insoluble (do not dissolve) in water.
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5. Where Can We Find Fats?
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See Fats In Foods Link
separate from this power
point.

6. Triglycerides
• Triglycerides are composed of:
• Three fatty acid molecules
• Fatty acids are long chains of carbon atoms
surrounded by hydrogen atoms.
• One glycerol molecule
• Glycerol is a three-carbon alcohol that is the
backbone of a triglyceride.
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7. Triglycerides
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8. Triglycerides
• Fatty acids can differ in:
• Level of saturation (hydrogen bonds)
• Saturation refers to how many hydrogen atoms
surround each carbon.
• Shape
• Straight chains of fatty acids form solids (butter,
lard), while kinked chains are less solid and
usually exist as fluids at room temperature (oils).
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9. Triglycerides
• Saturated fatty acids have hydrogen atoms
surrounding every carbon in the chain.
• Monounsaturated fatty acids lack hydrogen
atoms in one specific location.
• Polyunsaturated fatty acids lack hydrogen
atoms in multiple locations.
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10. Triglycerides
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11. Triglycerides
• The shape of a triglyceride is determined by the
saturation of the carbon chains.
• Saturated fatty acids can pack tightly together
and are solid at room temperature.
• For example, animal fats, butter, and lard are
high in saturated fatty acids.
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12. Triglycerides
• Unsaturated fatty acids:
• Do not stack together well
• Are liquid at room temperature
• Are present in plant oils
• May be:
• Monounsaturated – one double bond
• Polyunsaturated – more than one double bond
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13. Triglcerides
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14. Triglycerides
• Hydrogenation: the addition of hydrogen atoms
to unsaturated fatty acids
• Converts liquid fats (oils) into a more solid
form
• Used to create margarine from oils
• Often creates trans fatty acids
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15. Triglycerides
• Trans fatty acids:
• Are detrimental to health
• Change the way our cell membranes function
• Reduce the removal of cholesterol from the
blood
• Any partially hydrogenated oil (PHO) listed on a
nutritional label is usually a trans fat.
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16. Triglycerides
• Essential fatty acids
• Two fatty acids cannot be made in the body and
must be obtained from food.
• Linoleic acid (omega-6 fatty acid), found in
vegetable and nut oils
• Source of EPA and DHA
• Alpha-linolenic acid (omega-3 fatty acid),
found in vegetables, fish, and fish oils
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17. Phospholipids
• Phospholipids are:
• Composed of glycerol, two fatty acids, and
phosphate
• Soluble in water
• Manufactured in our bodies so they are not
required in our diet
• A critical component of cell membranes
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18. Phospholipids
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19. Sterols
• Sterols: lipids containing multiple rings of
carbon atoms
• Are essential components of cell membranes
and many hormones
• Are manufactured in our bodies and therefore
are not essential components of our diet
• Include cholesterol
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20. Sterol Structure
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21. Why Do We Need to Eat Fats?
• Energy
• Fats provide 9 kcal per gram.
• Fat is very energy-dense.
• 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.
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22. Why Do We Need to Eat Fats?
• Fat-soluble vitamins
• Vitamins A, D, E, and K are soluble in fat; fat
is required for their transport.
• Fats are essential to many body functions.
• Cell membrane structure
• Protection of internal organs
• Insulation to retain body heat
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23. Why Do We Need to Eat Fats?
• Fats provide flavor and texture to foods.
• Fats contribute to making us feel satiated
because:
• Fats are more energy-dense than
carbohydrates or protein.
• Fats take longer to digest.
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24. Digestion of Fats
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See Fat Digestion Link
separate from this power
point.

25. Digestion of Fats
• Fats are not digested and absorbed easily
because they are insoluble in water.
• Enzymes in the mouth and stomach can digest
only about 10% of the fats present.
• The gallbladder, liver, and pancreas assist in fat
breakdown.
• Most digestion of fats begins in the small
intestine.
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26. Digestion of Fats
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27. Digestion of Fats
• As fat enters the small intestine:
• Bile is produced by the liver and stored in the
gallbladder.
• Bile is secreted from the gallbladder into the
small intestine.
• Bile disperses fat into smaller fat droplets.
• Pancreatic enzymes break fat into two fatty
acids and a monoglyceride.
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28. Digestion of Fats
• Fatty acids are arranged as lipoproteins for
absorption and transport.
• Chylomicron: a lipoprotein produced by cells
lining the small intestine
• Composed of fatty acids surrounded by
phospholipids and proteins
• Soluble in water
• Chylomicrons transport consumed fats to the
bloodstream
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29. Structure of a Lipoprotein
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30. Absorption of Fats
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See Lipid Absorption
Link separate from
this power point.

31. Absorption of Fats
• Chylomicrons are absorbed by cells of the small
intestine, then they:
• Travel through the lymphatic system
• Are transferred to the bloodstream
• Short-chain fatty acids are absorbed directly into
the bloodstream.
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32. Absorption of Fats
• After entering body cells, triglycerides can be:
• Used immediately for energy
• Used to make lipid-containing compounds
(e.g., some hormones, bile)
• Stored in muscle or adipose tissue
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33. How Much Fat Should We Eat?
• The Acceptable Macronutrient Distribution Range
(AMDR) for fat:
• 20–35% of calories should be from fat
• Athletes and highly active people may need more
energy from carbohydrates but 20–35% of
calories still should be from fat.
• Very low fat diets (less than 20% of total calories)
do not provide additional health or performance
benefits.
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34. How Much Fat Should We Eat?
• The Acceptable Macronutrient Distribution Range
(AMDR) for essential fatty acids:
• 5–10% of energy from linoleic acid
• 0.6–1.2% of energy from alpha-linolenic acid
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35. How Much Fat Should We Eat?
• The type of fat consumed is important.
• Saturated fat should be between 5% and 6%
of total energy
• Trans fatty acids should be reduced to the
absolute minimum.
• Most fat in our diets should come from
unsaturated fats
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36. Choosing Foods with Helpful Fats
• Visible fats
• Fats we knowingly add to foods
• Butter, cream, mayonnaise, dressings
• Invisible fats
• Fats hidden in foods
• Naturally occurring or added during
processing
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37. Food Sources of Fats
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See Lipoprotein Link
separate from this power
point.

38. Food Sources of Beneficial Fats
• Eat more fish.
• Mercury and PCB concerns
• Choose plants.
• Opt for low-fat.
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39. Omega-3 Fatty Acid Content of Selected Foods
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40. Fat Comparison of Selected Foods
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41. What Role Do Fats Play in Chronic Disease?
• Cardiovascular disease
• Dysfunction of the heart or blood vessels
• Coronary artery disease
• Stroke
• Hypertension
• Dietary fats play an important role in
cardiovascular disease.
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42. Cardiovascular Disease
• Blood lipids include:
• Chylomicrons
• VLDLs: very-low-density lipoproteins
• LDLs: low-density lipoproteins
• "Bad cholesterol"
• HDLs: high-density lipoproteins
• "Good cholesterol"
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43. Lipoproteins
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44. Composition of Lipoproteins
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45. Composition of Lipoproteins
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46. Composition of Lipoproteins
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47. Composition of Lipoproteins
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48. Cardiovascular Disease
• Diets high in saturated fats, simple sugars and
extra energy tend to increase VLDLs.
• Diets high in saturated and trans fats tend to
increase LDL levels.
• Diets high in omega-3 fatty acids tend to
increase HDL levels.
• Diets high in saturated and trans fats tend to
increase Cholesterol levels.
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49. Cardiovascular Disease
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50. Cardiovascular Disease
• Trans fatty acids:
• Can raise blood LDL levels as much as
saturated fat
• Are abundant in hydrogenated vegetable oils
(margarine, vegetable oil spreads)
• Should be reduced to the absolute minimum
in the diet
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51. Cardiovascular Disease
• Risk factors for cardiovascular disease include:
• Being overweight
• Physical inactivity
• Smoking
• High blood pressure
• Diabetes
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