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Lipids Lipid is the chemical term for fat. Lipids contribute texture, taste, flavor and aroma to foods. Fats and oils contain 9 calories per gram. The typical American diet contains about 33% of its energy from fat.
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Chapter 5Lipids
Why may sugar alcohols be used in products labeled “sugar free” or “no sugar added”? Sugar alcohols provide no kilocalaries incorrect, they
provide differing amounts kcal Sugar alcohols are not derivatives of sugars incorrect,
some are derived from sugar which has undergone chemical processing such as hydrogenation
Sugar alcohols are not monosaccharides or disaccharides. incorrect
Sugar alcohols are not absorbed into the body. correct
Copyright 2010, John Wiley & Sons, Inc.
Copyright 2010, John Wiley & Sons, Inc.
Lipids
Lipid is the chemical term for fat. Lipids contribute texture, taste, flavor and
aroma to foods. Fats and oils contain 9 calories per gram. The typical American diet contains about
33% of its energy from fat.
Copyright 2010, John Wiley & Sons, Inc.
Fat Intake Affects Health
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Triglycerides
Triglycerides are the major form of lipid in food and in the body.
Triglycerides consist of three fatty acids attached to a glycerol molecule.
If only one fatty acid is attached to the glycerol it is called a monoglyceride.
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Triglycerides
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Review: Monosaccharide structure
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Most fatty acids in food and in the body are bound to a molecule called
cholesterol.
phospholipids.
lecithin. glycerol.
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Fatty Acids The carbon chains of fatty acids vary in length from
a few to 20 or more carbons. Short-chain fatty acids range from 4-7 carbons and
remain liquid at room temperature. Coconut oil is a medium chain fatty acid.
Copyright 2010, John Wiley & Sons, Inc.
Saturated fatty acids contain carbons in a chain that are bound to two hydrogens.
•Most animal fats contain saturated fatty acids.
Unsaturated fatty acids contain some carbons that are not saturated with hydrogens.
•Omega-3 and omega-6 fatty acids are unsaturated fatty acids.
Copyright 2010, John Wiley & Sons, Inc.
Fatty Acids
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Foods consisting mostly of fatty acids with only single bonds tend to be
solid at room temperature.
soluble in water.
liquid at room temperature.
gaseous at room temperature.
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The end of a fatty acid chain containing a methyl group is also referred to as the __________ end.
omega alpha delta beta
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Omega-3 and Omega-6 Fatty Acids
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Trans Fatty Acids
Trans fatty acids can be created by hydrogenation.
Hydrogenation causes some double bonds to become saturated.
Hydrogenated fats can be found in margarines, vegetable shortening and shelf-stable baked goods.
Trans fatty acids have be shown to raise blood cholesterol levels and increase the risk of heart disease.
Copyright 2010, John Wiley & Sons, Inc.
Fatty Acids in Food
Copyright 2010, John Wiley & Sons, Inc.
Phospholipids
Phospholipids are lipids attached to a phosphate group.
Phosphoglycerides are the major class of phospholipids.
Phosphoglycerides can act as emulsifiers. Phosphoglycerides form a lipid bilayer in
membranes, helping to regulate what can pass into and out of a cell.
Copyright 2010, John Wiley & Sons, Inc.
Phospholipids
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Phospholipids consists of glycerol with __________ attached.
3 fatty acids
3 amino acids
2 fatty acids, and a phosphate group
cholesterol
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Sterols
Sterols are a type of lipid found in plants and animals. Sterols do not dissolve in water. Cholesterol is a type of sterol found only in animals. 90% of cholesterol in the body is found in cell
membranes. Diets high in cholesterol (from animals) can increase
the risk of heart disease. Plant sterols can help reduce cholesterol in the body.
Copyright 2010, John Wiley & Sons, Inc.
Copyright 2010, John Wiley & Sons, Inc.
Bile, vitamin D, and some hormones such as testosterone and estrogen are derived from
essential fatty acids.
cholesterol.
trans fatty acids.
phospholipids.
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Chylomicrons
Chylomicrons are a combination of triglycerides, cholesterol, phospholipids and a small amount of protein.
Chylomicrons help to transport long-chain fatty acids into the lymphatic system and into the blood stream without passing through the liver.
Copyright 2010, John Wiley & Sons, Inc.
Chylomicrons
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Chylocmicrons are formed in:
the intestine
the liver
the lymph
the blood
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Reverse cholesterol transport is accomplished by
a) chylomicrons.
b) LDLs.
c) VLDLs.
d) HDLs.
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Lipoproteins
Lipoproteins are transport particles for water-insoluble lipids.
Lipoproteins are created by combining water-insoluble lipids, phospholipids and proteins.
Lipoproteins help transport triglycerides, cholesterol and fat-soluble vitamins from the small intestine and stored lipids from the liver.
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Lipoproteins
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Low-Density Lipoproteins
The liver is the major lipid-producing organ in the body.
Triglycerides produced in the liver are incorporated into entities called very-low-density lipoproteins (VLDLs).
VLDLs transport lipids out of the liver and deliver them to cells in the body.
The enzyme lipoprotein lipase removes triglycerides from VLDLs, creating intermediate-density lipoproteins (IDLs).
Copyright 2010, John Wiley & Sons, Inc.
Low-Density Lipoproteins Approximately two-thirds of IDLs return to the
liver; the remainder are transformed in the blood into low-density lipoproteins (LDLs).
LDLs contain less triglyceride and more cholesterol than VLDLs. LDLs deliver cholesterol to the cells.
If the amount of LDL cholesterol in the blood exceeds the amount that can be used by the cells, the result is a high level of LDLs.
High levels of serum LDLs have been associated with an increased risk for heart disease.
Copyright 2010, John Wiley & Sons, Inc.
High-Density Lipoproteins
Most cells cannot break down cholesterol. Cholesterol is returned to the liver to be eliminated from
the body. This reverse cholesterol transport is done by high-
density lipoproteins (HDLs). High levels of HDL in the blood help to prevent
cholesterol from depositing in the artery walls. High levels of HDL are associated with a reduction in
heart disease risk.
Copyright 2010, John Wiley & Sons, Inc.
Lipid Functions in the Body
Most lipids in the body are triglycerides stored in adipose tissue.
Deposits of adipose tissue help to define body shape, provide stored energy, insulate the body from temperature changes and protect internal organs against physical shock.
Lipids in the body are important for lubricating body surfaces, such as the mucous membranes of the eyes.
Copyright 2010, John Wiley & Sons, Inc.
If you were to analyze the composition of adipose tissue, you would likely find an abundance of
a) micelles.
b) triglycerides.
c) eicosanoids.
d) cholesterol.
Copyright 2010, John Wiley & Sons, Inc.
Lipid Functions in the Body
Cholesterol is used to make several hormones, including estrogen and testosterone.
PUFAs help to regulate blood pressure and blood clotting.
Essential fatty acids are important for growth, skin integrity, fertility and the structure and function of cell membranes.
Copyright 2010, John Wiley & Sons, Inc.
Lipid Functions in the Body
Eicosanoids are made from omega-3 and omega-6 fatty acids. Eicosanoids help regulate blood clotting, blood pressure and immune function.
Fatty acids and glycerol can be used to produce energy in the form of ATP.
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Lipids Can Be Used to Produce Energy in the Body
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Essential Fatty Acid Deficiency If adequate amounts of essential fatty acids
are not consumed, a deficiency can result. Symptoms include: dry, scaly skin, liver
abnormalities, poor wound healing, growth failure in infants and impaired hearing and vision.
Copyright 2010, John Wiley & Sons, Inc.
Lipids and Cardiovascular Disease Over 80 million Americans suffer from some
form of cardiovascular disease. Studies show that diet and lifestyle affect the
risk of developing cardiovascular disease. Atherosclerosis is a disease in which lipids
and fibrous materials are deposited in artery walls.
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Lipids and Cardiovascular Disease
Copyright 2010, John Wiley & Sons, Inc.
Lipids and Cardiovascular Disease
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Lipids and Cardiovascular Disease Dietary factors that may help to reduce the
risk of heart disease include: Consuming omega-3 and omega-6
polyunsaturated fats Consuming monounsaturated fats Consuming plant foods, including fruits and
vegetables, whole grains and legumes Adequate intake of B vitamins Moderate alcohol consumption
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Recommendations to Reduce Blood Cholesterol
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Tools for Assessing Fat Intake
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Tools for Assessing Fat Intake
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Tools for Assessing Fat Intake
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Tools for Assessing Fat Intake
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Dietary Fat and Cancer Dietary Fat has been suggested to be both a
tumor promoter and a tumor initiator.
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How to Choose Fats Wisely
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How to Choose Fats Wisely
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Reduced-Fat Foods
Reduced-fat foods either have fat removed, have fat replaced or contain fats that cannot be digested or absorbed.
Fat substitutes can be carbohydrate-, protein- or fat-based.
Fat-based fat substitutes, such as Olestra (sucrose polyester), can reduce the absorption of fat-soluble vitamins.
Copyright 2010, John Wiley & Sons, Inc.
Chapter 5
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