Chapter 5: Lipids
How does cholesterol affect digestion of fats in the small intestine
As a component of bile, it emulsifies fats
Why are the chemical structures of trans and saturated fatty acids similar?
Both have a straight shape
What do triglycerides and phospholipids have in common?
Built on a backbone of glycerol
Essential fatty acids _____ be synthesized in the body
Cannot
Cis fatty acid
Causes the carbon chain to bend
What deficiency would you suspect is a person has flaky and itchy skin, diarrhea, and poor wound healing with infections?
Essential fatty acids
Choose the fish species that are highest in mercury
-Swordfish -Shark -King mackerel
LDL function
Carries cholesterol made by the liver and from other sources to cells
Chylomicron function
Carries dietary fat from the small intestine to cells
VLDL function
Carries lipids made and taken up by the liver to cells
Fatty acid structure
Chain of carbons flanked by hydrogens
Myocardial infarction
Blood flow surrounding the heart is blocked resulting in damage to the heart muscle
Cerebrovascular accident
Blood flow to parts of the brain is blocked resulting in the death of brain cells
Immediately after a meal, newly digested and absorbed dietary fats appear in the lympt and then the blood as part of _____. a) Low-density Lipoproteins b) High-density Lipoproteins c) Chylomicrons d) Cholesterol
Chylomicrons
HDL function
Contributes to cholesterol removal from cells and excretion from the body
_____ is a phospholipid and a major component of cell membranes
Lecithin
Phospholipid definition
Lecithin is an example of this lipid
What enzyme breaks down triglycerides into free fatty acids and glycerol in the bloodstream?
Lipoprotein lipase
Triglyceride chemical structure
Three fatty acids attached to a glycerol backbone
Choose a lipid that can be synthesized by the body?
cholesterol
A compound containing a multi-ring structure and a hydroxyl group is a
sterol
Which of the following are types of lipoproteins?
-LDL -HDL -VLDL
Which of the following food ingredients indicate the presence of fat in a food product?
-Lard -Cream -Partially hydrogenated vegetable oil -Egg yolks -Shortening
What are some examples of foods that are considered high in fat?
-Margarine -Salad oils -Butter -Mayonnaise
Enzymes that digest fat are secreted by the ______.
-Stomach cells -Pancreas -Salivary glands
What happens to a food product when it becomes hydrogenated?
-The molecular shape of the fats in the food resembles saturated fats -Trans fatty acid content is increased
True statements about avocados
-They are rich in monounsaturated fatty acids -They can be substituted 1:1 for butter in recipes for baked goods
One bowl of chicken tortilla soup has 5 grams of fat, which means that the food provides _____ kilocalories from fat
45
Having an HDL level above _____ mg/dl and a total cholesterol to HDL below _____ is especially protective of cardiovascular disease
60; 3.5:1
LDL primary component
Cholesterol
Omega-3 effect on blood-clotting and inflammation
Decrease blood-clotting and inflammation
Polyunsaturated fatty acids effect
Decreases blood levels of cholesterol
People who have impaired fat absorption (e.g., cystic fibrosis patients) may be at risk for
Deficiency of fat-soluble vitamins
Three fatty acids combine with glycerol to form
a triglyceride
Lipoproteins are important for: a) Transport of fats in the blood and lympathatic system b) Synthesis of triglycerides c) Synthesis of adipose tissue d) Enzyme production
a) Transport of fats in the blood and lymphathic system
Primarily, fatty acids are transported through the bloodstream
as part of lipoproteins
Omega-6 Classification
Essential fatty acid; Linoleic acid
Cholesterol is an essential nutrient
False
Phospholipids do not contain fatty acids within their molecular structure
False
Long-chain saturated fat food sources
Fat in beef, pork, lamb, lard
Lipid-loaded white blood cells that have surrounded large amounts of a fatty substance, usually cholesterol, on the blood vessel walls are called
Foam cells
Phospholipid structure
Glycerol backbone with fatty acids and at least one phosphorus-containing group
Triglyceride structure
Glycerol backbone with three fatty acids
Omega-6 effect on blood-clotting and inflammation
Increase blood-clotting and inflammation
Saturated fatty acids effect
Increases blood levels of cholesterol
What does it mean when a fatty acid is considered essential?
It must be supplied by the diet in order to maintain health.
Phospholipid
Lecithin
The enzyme _____ plays an important role in fat digestion
Lipase
Due to their high energy density (9 kcal per gram) _____ are the ideal form of energy storage for the body
Lipids
_____-density lipoprotein is considered the "bad" cholesterol
Low
Trans fat food sources
Margarine, shortening
Triglyceride definition
Most fat in the body and in food
Omega-9 Classification
Nonessential fatty acid
Fatty fish provide eicosapentaenoic acid (EPA) and docosahexaenoid acid (DHA), which are two ______ that important for brain and heart health
Omega-3 fatty acids
The majority of fatty acids in the body and in foods are _____-chain fatty acids
long
The majority of fat digestion is accomplished by
Pancreatic lipase
In 2015, the FDA determined that _____ are no longer "generally recognized as safe" for use in human food products
Partially hydrogenated oils
What is one of the most important functions of the phospholipid molecule?
Phospholipids help form cell membranes
_____ is a cholesterol-rich substance deposited in the blood vessels
Plaque
Which type of treatment is typically used when only one artery is blocked?
Precutaneous transluminal coronary angioplasty (PTCA)
Choose a function of fat tissue
Protect organs from injury
Chylomicron remnant
Removed from circulation by the liver and recycled to make other lipoproteins and bile acids
______ fatty acids consist entirely of carbon-carbon single bonds
Saturated
Which class of lipids may serve as precursors for hormone synthesis?
Sterols
Which of the following is the body's most efficient form of stored energy?
Triglycerides
An omega-3 fatty acid is
Unsaturated
Essential fatty acids
must be obtained from the diet
According to the American Health Association, to reduce risk for cardiovascular disease, saturated fats should contribute
no more than 5% to 6% of total kilocalories
Fatty acid
omega-6, omega-3
Monounsaturated fatty acid structure
one carbon-carbon double bond
Most foods containing saturated fatty acids are _____ at room temperature
solid
When fat is removed from a food, most manufacturers add _____ in its place
sugar
Polyunsaturated fatty acid
two or more carbon-carbon double bonds
What are some health benefits associated with consuming a diet high in omega-3 fatty acids?
-Reduced inflammation -Decreased blood triglyceride levels -Reduced risk of heart disease
How are long chain fatty acids absorbed?
-Reformed into triglycerides -Enter circulation via the lymphatic system
What is added to reduced-fat foods to compensate for the loss of taste and texture when fat is removed?
-Salt -Sugar
People who use mineral oil as a laxative at mealtimes risk deficiencies of
-Vitamin E -Vitamin D
Which of the following are functions of phospholipids in the body?
-Formation of cell membranes -Absorption and transport of nutrients -Digestion of fats
What are some examples of foods that may contain partially hydrogenates (trans) fats?
-French fries -Shortening -Potato chips -Stick margarine
What are the structural components of a triglyceride?
-Glycerol backbone -Three attached fatty acids
The cholesterol manufactured by the body is used to make
-Hormones -Bile acids
How many Kilocalories are in one gram of fat?
9
Free fatty acids
Absorbed by cells within the vicinity and reform into triglyceride for storage or use
In foods, what are the major sources of omega-3 and omega-6 fatty acids, respectively?
Alpha-linolenic; lineoleic
What two chemical groups are found at the end of either side of the fatty-acid carbon chain?
An acid group (COOH) and a methyl group (CH3)
What is the structure and function of glycerol molecules?
An alcohol containing three carbons; it is the backbone of a triglyceride molecule
_____ act(s) to emulsify fats in the small intestine, suspending them in digestive juices to enhance the action of digestive enzymes
Bile acids
The main reason for hydrogenating fats is to:
Change a liquid fat to a solid fat
Cholesterol definition
Characterized with a multi-ring structure
Enzymes released from the pancreas break _____ down to free cholesterol and fatty acids
Cholesterol
Plant oils are always _____-free
Cholesterol
Sterol
Cholesterol
Glycerol
Circulates back to the liver
Sterol chemical structure
Multi-ring structure with a hydroxyl group
A saturated fatty acids contains:
No double bonds
Some plants contain natural cholesterol-lowering compounds called
Plant sterols
Omega-3 fatty acids effect
Reduces inflammation responses, blood clotting, and triglycerides
A(n) _____ is made of three fatty acids attached to glycerol.
Triglyceride
A(n) _____ is made up of a glycerol backbone attached to 3 fatty acids.
Triglyceride
Lipids in foods and in the body are mostly in the form of _____
Triglycerides
Megadoses of nicotinic acid, a form of a B vitamin, can lower
Triglycerides
About half of the energy our body uses at rest and during low-intensity exercise (or light activity) comes from fatty acids.
True
Saturated fatty acid structure
no carbon-carbon double bond
What are some of the positive attributes of fat in the diet?
-Fat imparts a creamy texture to foods -Many flavors are fat soluble, so fat enhances the flavor of foods
Counting from the methyl end of an omega-3 fatty acid, the first double bond occurs between the
Third and fourth carbons
Heart disease is the _____ leading cause of death among North American adults
#1
Which statements are true about a diglyceride?
-It consists of two fatty acids bonded to glycerol backbone -it is the breakdown product of a triglyceride
Choose the two approaches to treating heart disease that have been shown to cause a reversal of atherosclerosis in the body.
-Aggressive LDL-lowering medications -Vegan diet and lifestyle changes that are part of the Dr. Dean Ornish program
What are the two most common synthetic antioxidant additives in foods?
-BHA -BHT
Current cholesterol-lowering medications act to
-Bind to cholesterol in the GI tract -Reduce cholesterol synthesis in the liver
What are some ways to limit trans fat intake at home?
-Broil, pan-fry, or grill meats instead of deep-fat frying with shortening -Use vegetable oils or softer tub margarines instead of stick margarine or shortening -Use reduced-fat or fat-free milk instead of non-dairy creamers
What are some components of plaque?
-Calcium -Cholesterol -White blood cells
What are some examples of food sources that contain cholesterol?
-Chicken -Ice cream -Eggs
Which of the following substances are types of lipids?
-Cholesterol -Triglycerides -Saturated fatty acids
Which of the following are functions of HDL cholesterol in the bloodstream?
-Donates cholesterol to other lipoprotein for transport back to the liver for excretion -Picks up cholesterol from dying cells and other sources
What two food types contribute the most to raising the level of cholesterol in your blood?
-Eating trans fat -Eating saturated fat
What are the products of fat digestion in the small intestine?
-Fatty acids -Monoglycerides
Arrange the following foods from lowest percentage of kcal from fat to the highest percentage of kcal from fat
1) Bread 2) Whole milk 3) Cheddar cheese 4) Canola oil
List the steps of the development of atherosclerosis in the arteries starting with arterial damage and ending with a heart attack
1) Damage occurs in blood vessel lining 2) Plaque is deposited at the sit of initial damage 3) As plaque accumulates, arteries harden, narrow, and lose elasticity 4) Clot or spasm in a plaque-clogged artery leads to a heart attack
Place the steps of dietary fat absorption in the order they occur
1) Glycerol, monoglycerides, and fatty acids are absorbed from the lumen of the small intestine into the small intestinal cells. 2) Triglycerides are reassembled within the cells lining the small intestine. 3) Triglycerides are packaged into chylomicrons. 4) Chylomicrons enter the lymphatic system.
Long-chain fatty acids contain ____ or more carbon atoms
12
A healthy blood pressure is less than _____ mm Hg for the systolic pressure and less than _____ mm Hg for diastolic pressure.
120; 80
The Acceptable Macronutrient Distribution Range set by the Food and Nutrition Board for lipids is _____% to ______% of kilocalories.
20; 35
Triglyceride
3 fatty acids and 2 glycerol molecule
Low fat definition
3g of fat or less per serving (or, if the serving size is small, per 50 grams of food)
How do you convert a liquid oil to a solid fat at room temperature?
Add hydrogens to the liquid fat (hydrogenation)
Trans fatty acid
Allows the carbon chain to remain straighter
Reduced or less fat definition
At least 25% less fat per serving in comparison to the full-fat version of the food product
Chylomicron primary component
Triglyceride
A major function of phospholipids (e.g., lecithin) in foods is to act as a(n)
emulsifier
Compared to foods made with unprocessed plant oils, partially hydrogenated oils are less likely to go rancid because
they have fewer double bonds
The intake of ____ fat should be kept as low as possible as recommended by Dietary Guidelines for Americans, the American Heart Association, and the Food and Nutrition Board
trans
High levels of HDL in the blood tend to slow the development of cardiovascular disease because HDL
transports cholesterol from the bloodstream to the liver for excretion
A recipe may have to be adjusted when substituting reduced-fat margarines for regular margarine because of the added _____ in the reduced-fat margarine
water
If you witnessed a person experiencing shortness of breath, nausea and vomiting, irregular heartbeat, sweating, and radiating pain in the upper body, you would suspect that this person is having a(n) _____.
Heart attack
Butter and margarine have about the same amount of fat, but the types of fatty acids and are margarine are different. Compared to margarine, butter has a ____ proportion of saturated fatty acids.
Higher
What is the chemical structure of an omega-3 fatty acid?
It contains the first carbon-carbon double bond on the third carbon from the omega end of the carbon chain.
How does the body respond when it is attempting to store fat and the existing fat cells are "full"?
It forms new adipose cells
Fat free definition
Less than 0.5g of fat per serving
What are the values for HDL and total cholesterol, respectively, that serve as risk factors for development of cardiovascular disease?
Less than 40 mg/dL; greater than 200 mg/dL in fasting state
Glycerol, fatty acids, and phosphorus-containing parts are all byproducts of _____ digestion
Phospholipid
Working as emulsifiers, important to the proper functioning of the nervous system, and having the ability to be soluble in fat and water are all function of
Phospholipids
Systolic Blood Pressure
Pressure in the arterial blood vessels associated with pumping of the blood from the heart
Diastolic Blood Pressure
Pressure in the arterial blood vessels when the heart is between beats
HDL primary component
Protein
_____ occurs when the double bonds in unsaturated fatty acids in food products are broken down by ultraviolet light or oxygen.
Rancidity
_____ reduces the shelf life of a product creating a problem for the food industry and restaurants. To prevent the problem, manufacturers add partially hydrogenated plant oils to products.
Rancidity
Phytosterols are plant chemicals that
Reduce cholesterol absorption in the small intestine
______ serve to stop the damage down to cells by oxidation
Antioxidants
Monounsaturated and polyunsaturated fatty acids are typically liquid at room temperature
True
Monounsaturated, saturates, and polyunsaturates fats all provide the same number of calories
True
Once a fat cell is filled with fat, the body can form new adipose cells
True
The CLA or natural trans fats decrease the risk of heart disease, cancer, and obesity
True
The body is able to produce all of the phospholipids it needs in order to maintain normal physiological function.
True
The process of oxidation usually changes the shape and/or function of a substance
True
What are some of the risk factors for cardiovascular disease?
-Smoking -High blood cholesterol -Family history of cardiovascular disease -Hypertension
Phytosterols are plant chemicals that can reduce blood cholesterol. They can be found in
-Speciality margarines and salad dressings -Pistachios and sunflower seeds -Pill form
Typical warning signs of a heart attack include
-Irregular heartbeat -Shortness of breath -Intense, prolonged chest pain or pressure, sometimes radiating to other parts of the upper body.
Which statements are true about a monoglyceride?
-It consists of one fatty acid bonded to a glycerol backbone -It is one of the products of digestion of triglycerides
Which of the following food sources are high in saturated fat?
-Cheeseburger -Butter -Coconut oil
What is the function of an emulsifier?
Suspends fats in water
Why is LDL considered "bad" cholesterol?
-Buildup of LDL in blood vessels contributes to atherosclerosis, a process that increases the risk of developing cardiovascular disease. -If not cleared from the bloodstream, LDL cholesterol builds up in the blood vessels
Just because a food is high in fat does not mean it is unhealthy. Some high-fat foods, such as plant oils and nuts, should be included in the diet because they are sources of
-Essential fatty acids -Fat-soluble vitamins
Characteristics of cholesterol:
-It is used for making estrogen and testosterone -It is converted to bile -It is incorporated into cell membrane
What are some examples of foods that are cholesterol-free?
-Margarine -Vegetable oil -Peanut butter -Vegetable shortening
How are the different types of fatty acids distinguished?
-Number of carbon-carbon double bonds along the skeleton -Length of the carbon skeleton -Position of carbon-carbon double bonds along the skeleton
In the listing of ingredients on a food label, the presence of _____ is an indication that a product is a source of trans fat.
-Partially-hydrogenated oils -Margarine
Which statements are true about omega-6 fatty acids?
-They are also called unsaturated fatty acids -The first carbon-carbon double bond is on the sixth carbon from the methyl end of the carbon chain
Which statements are true about sterols?
-They contain a multi-ring structure -Cholesterol is a common example -They can be produced by the body
What are some food sources of EPA and DHA?
-Tuna -Sardines -Salmon
Which of the following are true in terms of triglyceride digestion and absorption?
-Two outer fatty acids are removed prior to absorption -Digestion primarily occurs in the small intestine via pancreatic lipase -Fatty acids and monoglycerides are absorbed by the intestinal cells
List the steps of fat digestion and absorption starting in the mouth (top of the list) and ending in the small intestine
1) Some lipase is released by the salivary glands and stomach 2) Salivary lipase and gastric lipase begin digesting short-chain fatty acids in the stomach 3) Bile emulsified the fats 4) Pancreatic lipase digests long-chain fatty acids and triglycerides 5) Triglycerides are broken down and absorbed in the small intestine
Polyunsaturated fat food sources
Corn oil, fish oil, sunflower oil, safflower oil
Omega-3 Classification
Essential fatty acid; alpha-linolenic acid
Linoleic acid and alpha-linolenic acid are both
Essential fatty acids
Phospholipids are essential parts of only a few types of cells, like adipose and liver cells
False
Which of the following has only carbon-carbon single bonds?
Saturated fatty acid
What is the primary health risk associated with a high intake of trans fat?
Increased risk of heart disease
Why are triglycerides ideal for fat storage?
-They are chemically stable -They are energy dense
In terms of HDL and LDL levels, risk for development of cardiovascular disease increases when _____ level are low and _____ levels are high in the bloodstream
HDL; LDL
Formed from the breakdown of triglycerides, a _____ consists of one fatty acid attached to a glycerol backbone
Monoglycerides
Sterol structure
Multi-ringed compound with a hydroxyl group
Quantity fat recommendation
Need not be altered to maintain a healthy diet
Quality fat recommendation
Needs to be increased by choosing fewer saturated and trans fatty acids
Monounsaturated fat food sources
Olive oil, canola oil, peanut oil
Considering their health effects, trans fatty acids are most similar to
Saturated fatty acids
A _____ is a lipid with a multi-ringed structure
Sterol
Omega-6 molecular structure
The first carbon-carbon double bond is located on the sixth carbon from the omega, or methyl, end of the structure
Omega-3 molecular structure
The first carbon-carbon double bond is located on the third carbon from the omega, or methyl, end of the structure