Download unit 6 lipids: focusing on fats and cholesterol - McGraw

Nutrition Essentials: A Personal Approach
Unit Outline
UNIT 6
LIPIDS: FOCUSING ON FATS AND CHOLESTEROL
OVERVIEW
Unit 6 focuses on the roles of lipids in the diet and in human physiology. The unit begins with an
overview of lipid chemistry, including functions and sources of fatty acids, triglycerides, phospholipids,
and cholesterol. The digestion, absorption, and metabolism of dietary fats are presented. The
essentiality of lipids in the diet is described, but the unit also includes a thorough review of the negative
health consequences of consuming excess lipids. There is a particular emphasis on the relationship
between dietary lipids and the development of cardiovascular disease. Many food and nutrition tips are
provided for achieving a healthy balance of fats in the diet.
LEARNING OUTCOMES
Module 6.1
1. Define all of the key terms in this module.
2. Identify the major lipids in your diet as well as their primary food sources and functions in your
body.
3. Explain the difference between a saturated and an unsaturated fatty acid.
4. Identify foods that are rich sources of saturated fat, monounsaturated fat, or polyunsaturated
fat.
5. Identify the two essential fatty acids and foods that are rich sources of these nutrients.
6. Identify sources of trans fats and explain why partially hydrogenated fats have been used in
foods.
Module 6.2
1. Define all of the key terms in this module.
2. Describe what happens to the fat and cholesterol in food as it undergoes digestion and
absorption in your intestinal tract.
3. Describe the function of a chylomicron.
Module 6.3
1. Define all of the key terms in this module.
2. Explain the process of atherosclerosis and describe how the condition contributes to CVD.
3. List major risk factors for atherosclerosis and indicate which factors are modifiable.
4. Discuss dietary and other lifestyle actions that can reduce your risk of atherosclerosis and
cardiovascular disease.
5. Identify major dietary sources of essential fatty acids.
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
UNIT OUTLINE
I. What Are Lipids (Module 6.1)
A. Introduction
1. Fats, oils, and cholesterol are lipids, a class of organic nutrients that
generally don’t dissolve in water
2. Lipids may play a role in:
a. Providing and storing energy (fat)
b. Maintaining cell membranes
c. Producing certain hormones
d. Insulating against cold temperatures
e. Regulating blood pressure and inflammation
f. Cushioning against bumps, blows, and falls
3. Dietary fat helps your body absorb fat-soluble vitamins and phytochemicals
4. Dietary lipids contribute to rich flavor, smooth texture, and appetizing
aroma of foods
B. Triglycerides
1. Comprise about 95% of lipids in your body and food
2. Referred to as fats and oils – fats
3. A triglyceride is composed of three fatty acid molecules attached to a
glycerol “backbone:” molecule
4. Each fatty acid has a chain of carbon atoms bonded to each other and to
hydrogen atoms
5. Fatty acids can be saturated or unsaturated
a. Saturated fatty acid – each carbon within the chain is completely filled
(saturated) with hydrogen atoms
b. Monounsaturated fatty acid – has two neighboring carbons within the
carbon chain that each lack a hydrogen atom
c. Polyunsaturated fatty acid – has more than one double bond in the
carbon chain
d. Review Comparing Sources of Saturated and Unsaturated FA (EC. 6.1)
e. Fat that contains a high proportion of unsaturated fatty acids, such as
sunflower seed oil or corn oil, tends to be liquid when stored at room
temperature
f. Essential fatty acids such as alpha-linoleic acid and linoleic acid cannot
be made by the human body
i.
Linoleic acid is an omega-6 fatty acid
ii.
Cells use alpha-linoleic acid to produce two other omega-3 fatty
acids eicosapentaenoic acid and docosahexaenoic acid
iii.
Cells can convert linoleic acid to arachidonic acid
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
6. Trans fatty acids (trans fat) are unsaturated fatty acids that have an unusual
type of chemical structure
a. When you purchase packaged foods, check the Nutrition Facts panel for
the amount of trans fat in the product, and if any hydrogenated fats are
in the products
b. Partial hydrogenation converts many of an oil’s naturally occurring
unsaturated cis fatty acids into trans fatty acids and saturated fatty
acids
c. Trans fats are less likely to become rancid (the shape is like that of a
saturated fat (oil is more solid at room temperature)
d. Foods with trans fats can be stored for longer periods of time, than can
foods that contain “regular” unsaturated fats
e. Populations that consume diets rich in saturated fat and trans fat have
higher risk of cardiovascular disease (CVD) than populations whose
diets contain more unsaturated fat
C. Cholesterol
1. Cholesterol is a sterol
2. It is a key nutrient that has a variety of functions in your body
3. Your liver uses cholesterol to make bile salts which help the small intestine
digest lipids
4. Dietary sources of cholesterol are only in animal foods
5. If your body makes too much cholesterol, the excess can increase your risk
of CVD
D. What Are Phospholipids?
1. Phospholipids are chemically similar to a triglyceride except that one fatty
acids is replace by chemical groups that contain phosphorus
2. The phosphate head is water soluble
3. The fatty acid tail is not water soluble
4. The membrane is flexible and allows fat-soluble compounds to move in and
out of the cell easily
5. Phospholipids are found natural in plant and animal foods in the form of
Lecithin
6. Lecithin contains choline a chemical nerves use to produce acetylcholine
7. Phospholipids can serve as an emulsifier, a substance that keeps fat-soluble
and water-soluble compounds together
II. What Happens to the Fat and Cholesterol You Eat? (Module 6.2)
A. Digesting Lipids
1. The small intestine is the primary site of lipid digestion
2. The pancreas release enzymes or lipases into the small intestine that digest
fats and phospholipids
3. Digesting Fat (E.C. 6.2)
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
a. Bile salts emulsify the lipids and keep them suspended as small particles
in chyme
b. The presence of chyme stimulate the pancreas to create pancreatic
lipase
c. Pancreatic lipase digest fat by removing two fatty acids from each
triglyceride molecule
d. Glycerol, fatty acids, and monoglycerides are the major products of lipid
digestion
e. Bile salts surround the fatty acids and monoglycerides to form a watersoluble particle called a micelle
B. Absorbing and Transporting Fat and Cholesterol
1. In absorptive cells the fatty acids and monoglyceride molecules are
reassembled into triglycerides
2. The absorptive cells coat the lipids with a thin layer of protein,
phospholipids, and cholesterol to form a chylomicrons
3. Chylomicrons are a type of lipoprotein that transports lipids through watery
environments such as the bloodstream
4. Lipase breaks down the chylomicron into fatty acids and glycerol
5. The liver clears the cholesterol-rich products from the bloodstream and uses
their contents to produce very-low-density lipoproteins (VLDL)
C. What Happens to the Bile Salts?
1. Recycling or Eliminating Bile Salts (E.C. 6.3)
a. Most used bile salts are absorbed in the small intestine (ileum)
b. Eating foods that contain soluble fiber can interfere with this recycling
process in the small intestine
c. Eliminating bile salts can reduce blood cholesterol levels
D. What Happens to Excess Fat That You Eat?
1. Adipose cells remove fatty acids and glycerol from the bloodstream and
reassemble them into fat for storage
2. Eating too much fat contributes to unwanted weight gain
3. Non-nutrient alcohol stimulates fat production
III. Cardiovascular Disease: Major Killer of Americans (Module 6.3)
A. The Road to Cardiovascular Disease (CVD)
1. Atherosclerosis is a long-term process that negatively affects the
functioning of blood vessels, especially arteries
2. The Process of Atherosclerosis (E.C. 6.4)
a. Normal arteries are flexible, tube-like structures that have a smooth
lining
b. Atherosclerosis can begin when something in the bloodstream, such as
excess cholesterol or glucose, or certain bacteria, which irritates the
lining of an artery
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
c. Inflammation can stimulate healing causing cells to leave deposits called
arterial plaque in the walls of blood vessels
d. Arterial plaque narrows and may even block the opening through which
blood flows in an artery
e. Sometimes a clot breaks away from the mass and travel through the
bloodstream towards smaller arteries
f. Cells may die if blood flow is disrupted due to lack of oxygen
3. Angina can result when arteries to the heart muscle are partially blocked
4. The tissue can die and a heart attack occurs
5. A stroke can happen when a clot blocks an artery in the brain, and brain
cells that are nourished by the blood vessel die
6. Peripheral vascular disease (PVD) occurs when an artery that does not carry
blood to the heart or brain dies
7. Hardening of the arteries or arteriosclerosis is cause by plaques that reduce
the flexibility of arteries
8. Hypertension develops due to inflexible arteries and may lead to high blood
pressure
9. Lipoproteins and Atherosclerosis
a. The body makes three major types of lipoproteins
b. Chylomicrons carry much more fat and very little protein
c. HDL is the smallest and densest
10. What Happens to Lipoproteins (E.C. 6.5)
a. Your liver uses the cholesterol that it makes and dietary cholesterol to
form very-low-density lipoprotein (VLDL)
b. After being stripped of most its fat, VLDL becomes low-density
lipoprotein (LDL)
c. LDL transports cholesterol and other lipids to tissues
d. The liver releases protein “shells” or high-density lipoprotein (HDL) into
the bloodstream that pick up cholesterol and other lipids from cells
11. Oxidized LDL Cholesterol
a. Some LDLs are smaller and denser than others
b. Chemically unstable free radical can damage small dense LDLs
c. The damage results in oxidized LDL cholesterol which is taken up by the
plaque-forming arterial cells
B. Risk Factors for Atherosclerosis
1. Medical experts haven’t been able to determine a cause for atherosclerosis
2. Major risk factors:
a. Unhealthy blood cholesterol levels
b. Hypertension
c. Smoking
d. Insulin resistance
e. Diabetes
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
f. Excess body fat
g. Lack of physical activity
h. Poor diet
i. Increasing age
j. Family history of CVD
3. Condition that may be risk factors:
a. Genetics
b. C-reactive protein
c. Triglycerides
d. Sleep apnea
e. Emotional stress
f. Alcohol
C. Reducing your Risk of Atherosclerosis and CVD
1. You can lower your chances of developing atherosclerosis by changing your
lifestyle
a. Be more physically active
b. Replace saturated FAs and trans fat with MFAs and PUFAs
c. Quit smoking
d. Limit salt intake
e. Achieve and maintain a healthy weight for height
f. Eat more fiber-rich foods
g. Continue foods that contain antioxidants
h. Reduce sugar and alcohol intake
2. Focus on Dietary Fats (Effects of Dietary Fat on LDL and HDL – EC 6.6)
a. Saturated fat contributes much of the calories in fatty meats, luncheon
meats, sausage, hot dogs, and “full-fat” dairy products such as hard
cheeses and whole milk
b. Following a diet that supplies more MFAs than saturated FAs may lower
your risk of CVD
c. Most saturated FAs increase blood cholesterol levels by raising LDL
cholesterol
d. Trans fats raise blood cholesterol levels
e. MFAs lower LDL cholesterol with reducing HDL cholesterol levels
f. Diets containing more polyunsaturated FAs than saturated FAs may
reduce blood levels of total cholesterol and LDL-cholesterol
3. A “heart-healthy” diet emphasis seafood, olive oil, whole grains, beans,
fruits, and vegetables
D. Assessing Your Risk of Atherosclerosis
1. Have regular medical checkups
2. The physician may request a blood test assess cholesterol and triglyceride
levels
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
3. To calculate your risk of having a future heart attack, use the risk
assessment tool at http://www.nhlbi.nih.gov/health/index.htm
4. Recommendations for Fat and Cholesterol Intakes can be found in the
Dietary Guidelines
5. Increase your intake of essential fatty acids from dietary sources to include:
a. Eat seafood
b. Bake or grill or broil fish
c. Add water-packed can tuna or salmon to salads
d. Use vegetable oils, liquid margarines, or soft margarines
e. Sprinkle chopped walnuts on salads, yogurts, or cereal, or simply eat
nuts as a snack
6. Eating fish is the best way to obtain omega-3 fatty acids
7. For people with high triglyceride levels high, levels of fish oil can reduce
their levels of lipids
8. Heart Healthy Food Selection and Preparation Tips
a. Choose lean cuts of meat
b. Use moist cooking methods for lead cuts of meat
c. Reduce the oven temperature when cooking meat
d. Trim away visible fat from the meat
e. Stem meats and vegetables
f. Don’t use pan drippings to make gravies or sauces
g. Stir-fry pieces of raw vegetables, meat, fish, shellfish etc.
h. Brown ground beef in a pan, then drain beef fat
i. Avoid dipping raw foods in batter or breading and deep frying
j. Switch from drinking whole or 2% to 1% or fat-free milk
k. Use less salad dressing on salads
l. Commercial frosting are likely to be high in hydrogenated oils
m. Substituting tub or diet margarines for butter in recipes is not
recommended
n. Read the Nutrition Facts panel and the ingredient list on the label
o. Eat fewer commercially prepared baked goods, snack foods, and fried
fast-food items
p. Purchase brands of microwave popcorn that have little added fat or no
trans fats
q. Replace some fatty foods with reduced-fat or fat-free alternatives
r. Substitute plain, fat-free yogurt in recipes that call for sour cream
s. Replace half or all of the solid fat or oil in recipes for baked goods with
unsweetened applesauce
t. To lower the fat content of their products, manufacturers of “lite”
spreads may have water as the first ingredient
u. Use peanut or soy nut butters instead of cheese or luncheon meat in
sandwiches
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part
Nutrition Essentials: A Personal Approach
Unit Outline
9. What if Lifestyle Changes Don’t Work?
a. Discuss additional treatment options with your physician
b. Classes of prescription drugs are known to reduce cholesterol levels
c. Questions have been raised about the safety of these medications, i.e.
(Statins, Zetia)
Copyright © 2015 McGraw-Hill Education. This is proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any
manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or posted on a website, in whole or part