NUTR 2105 Lecture Notes - Lecture 5: Saturated Fat, Methyl Group, Carboxylic Acid
1 May 2018
School
Department
Course
Professor
What are lipids and how differ in structure ?
Lipids refer to a category of compounds that include:
Triglycerides
§
Phospholipids
§
Sterols
§
○
Contain C, O, and H (same structure as carbs except…)
○
Hydrophobic, which means they don't dissolve in water
○
Basic functions in body
Store and provide energy
§
Provide insulation
§
Help manufacture steroids and bile
§
Play a role in transporting fat-soluble nutrients in the blood
§
Used to manufacture sex hormones
§
Key to the structure of cell membranes
§
○
Many lipids are comprised of fatty acids
Building blocks of triglycerides and phospholipids
§
Chain of C and h atoms w/ a carboxyl group at the alpha end and a
methyl group at the omega end
§
Fat has more cals (9) then carbs or proteins (4) b/c of higher ratio of
C and H to O
§
4 types of fatty acids which vary by
Length of carbon chain
2 to 80 carbons long
Most common 12 to 24 carbons
◊
®
Short-chain fatty chains
2-4 carbons
◊
®
Medium-chain fatty acids
6-10 carbons
◊
®
Long-chain fatty acids
12 or more carbons
◊
Most common type in foods and take longer to
digest than short or medium-chain fatty acids
◊
®
□
Degree of saturation
Determined by whether carbons are held together by a
single or double bond
®
Saturated fatty acids
All carbons on fatty acid bound to hydrogen
◊
No double bonds
◊
Solid at room temp
◊
Have a higher melting point
◊
®
Unsaturated fatty acids
Some carbons on fatty acid form a double bond
/w each other instead of binding to hydrogen
◊
Tend to be liquid at room temp
◊
Have a lower melting temp
◊
Monounsaturated fatty acid (MUFA)
Has one double bond
}
◊
Polyunsaturated fatty acid (PUFA)
Has 2 or more double bonds
}
◊
®
□
Stability of fatty acids
Rancidity: spoiling of fats through oxidation
Double bonds are less stable than single bonds
◊
Foods w/ unsaturated fats become rancid faster
than foods w/ saturated fats (b/c have double
bonds)
◊
Manufacturers have enhance the stability of fatty
acids by:
Adding antioxidants
}
Limiting food exposure to oxygen, heat, and
light
}
Hydrogenation
}
◊
®
Location of double bond
Location of first double bond from methyl (or
omega) end of unsaturated fatty acids affects
properties of fatty acids
Omega-3 fatty acid
First double bond is b/w 3rd and 4th
carbons from omega end
–
Ex. Alpha-linolenic acid
–
}
Omega-6 fatty acid
First double bond is b/w 6th and 7th
carbons from omega end
–
Ex. Linoleic acid
–
}
◊
®
□
Shape
Unsaturated fatty acids form 2 diff shapes based on the
position of the H atoms around the double bond
®
□
§
○
Triglycerides are the most common lipid
Make up about 95% of lipids in foods
§
Has 3 fatty acids connected to a glycerol backbone (like upper case
E)
§
Functions
Add texture to baked goods□
Makes meat tender□
Preserve freshness□
Stored as adipose tissue for energy□
However: high level in blood are risk factor for heart disease□
§
○
Phospholipids
Differ from triglycerides b/c while made of a glycerol backbone, 2
fatty acids, a phosphate group, and diff nitrogen-containing
compounds
Lecithin (aka phosphatidylcholine) is a type of phospholipid
Synthesized by liver
®
Functions:
Use as an emulsifier in food (ex. Salad dressing,
bile, etc.)
◊
A major phospholipid in cell membrane
◊
®
□
§
Hydrophilic on one end; hydrophobic on the other
§
Make up the phospholipid bilayer in the cell membrane
§
○
Sterols are more complex than triglycerides
Made of 4 connecting rings of carbon and hydrogen
Do not contain glycerol or fatty acids□
They do not provide energy□
§
Cholesterol is the best known sterol
Found in every cell in the body□
Helps w/ numerous body processes□
Precursor to vitamin D, sex steroids, and adrenal corticoids □
§
Phytosterols and phytostanols are major plant sterols
§
○
-
How are lipids digested, absorbed, and transported?
Lipids from food primarily in the form of triglycerides
Lesser extent phospholipids and sterols
§
○
During digestion, fatty acids form a combination of free fatty acids,
glycerol, and monoglycerides
○
Lipases are the enzymes that digest lipids
○
Digestion begins in mouth w/ chewing
Mixes w/ saliva and lingual lipase
Lingual lipase hydrolyzes the medium-chain fatty acids□
§
○
The bolus of food travels through the esophagus into the stomach
Stomach muscles
§
Gastrin is released from gastric pits lining stomach and stimulates
release of gastric juices, rich in gastric lipase
§
Gastric lipase hydrolyzes one fatty acid from the triglyceride, which
produces a free fatty acid and a diglyceride
§
○
Most triglycerides are digested and their components are absorbed in the
small intestine
Fat globules in chyme tend to cluster together
§
In the intestine, bile acid emulsifies larger fat droplets into smaller
fat droplets
This allows pancreatic lipase to digest the lipids easily (which
is the enzyme responsible for the majority of lipid digestion)
□
The resulting lipid complex is micelle (clusters of fatty acids,
monoglycerides, and other lipids surrounded by bile salts that
transport lipids across the cell membrane of the villi)
Transport the lipid complex across the small intestinal
wall
®
□
§
Cholecystokinin (CCK) is the hormone that stimulates the
gallbladder to release bile acid
CCK is released by cells of duodenum in presence of lipids□
§
Phospholipids
Emulsified by bile during digestion□
Dismantled into 2 free fatty acids and phospholipid remnant□
Packaged as micelles□
Transported through intestinal wall□
§
Sterols
Not digested□
Carried by micelle and absorbed intact through intestinal wall□
Bile emulsifies sterols□
§
If lipids are undigested and not absorbed in small intestine:
Bind w/ fiber□
Are eliminated in feces □
§
○
Chylomicrons facilitate lipid absorption
Lipids are absorbed based on structure
Glycerol and short to medium-chain fatty acids are absorbed
directly into bloodstream
□
Long-chain fatty acids combine w/ phospholipids and
cholesterol to form chylomicrons
□
§
Chylomicrons are too large to be absorbed directly into the
bloodstream
Travel through lymph fluid first□
Exit the lymph and enter bloodstream through thoracic duct
next to heart
□
Lipoprotein lipase (LPL) hydrolyzes triglycerides in the
chylomicrons as they travel to the liver via bloodstream
□
Not made in liver**□
§
○
Lipoproteins transport lipids
4 kinds of lipoproteins that carry lipids through circulatory system
Chylomicrons□
Very-low-density lipoproteins (VLDLs)
Transport triglycerides (TGs) and cholesterol from the
liver to the cells
®
Lipoprotein lipase located on the outside of adipocytes
and muscle cells cleave fatty acids (FAs) from TGs
FAs move into adipocytes and muscle cells and
stored for later use
◊
Increases ratio of protein to lipids
◊
Process converts VLDLs to LDLs
◊
®
□
Low-density lipoproteins (LDLs)
Carry cholesterol from the liver to the tissues
®
"bad cholesterol"
®
"lousy" DLs
®
□
High-density lipoproteins (HDLs)
Carry cholesterol from the cells to the liver
®
"good cholesterol"
®
"healthy" DLs
®
□
§
VLDLs, LDLs, and HDLs
Globular molecule w/ a lipid center surrounded by a plasma
membrane
□
Density determines function□
More protein= high density □
HDL and LDL biomarkers are used to determine the health of
arteries
□
§
○
-
What are the functions of lipids in the body
Several critical roles in the body
Source of energy
Fatty acids provide a concentrated source of cals
9 cals/ g
®
□
Readily available when body needs energy□
Body's main source of energy throughout day□
Excess fat is stored
Body has unlimited ability to store excess energy as fat
in adipocytes
Fat cells can grow up to 1,000 times their original
size
◊
Additional fat cells are made when fat stores are
filled
◊
®
Some fat is stored in muscle cells
®
□
Fats are a powerful fuel source
Preferred by heart, liver, and resting muscle
®
Spares glucose so it is the only used by CNS and red
blood cells
®
Provides a backup source of energy b/w meals
®
Cannot sustain life during prolonged starvation
Glucose is needed to metabolize fat
◊
The glycerol protein of fat can make small
amounts of glucose
◊
®
□
§
Form body structures (including cell membranes)
§
Regulate metabolism
§
Enhance the absorption of fat-soluble vitamins
Dietary fat aids in absorption of lipid compounds
Several essential nutrients require dietary fat for
absorption
Fat-soluble vitamins
◊
Carotenoids
◊
Cholesterol
◊
Phospholipids
◊
®
Twenty grams/ day needed to stimulate chylomicrons
that transport fat-soluble vitamins
®
□
§
Provide a layer of insulation to help regulate body temp
Fat in subcutaneous tissue
Insulates body
®
Maintain body temp
®
□
Fat protects bones and vital organs from trauma□
Too much stored fat can be detrimental to health and
increase risk for heart disease, hypertension and diabetes
□
§
Help cushion major organs
§
○
Essential fatty acids manufacture eicosanoids (made via the oxidation of
polyunsaturated fats and are involved in cellular activity, also noted for
role in inflammation) and cell membranes
Linoleic acid
Converted to arachidonic acid□
§
Alpha-linolenic acid (ALA)
Converted to eicosapentanoic acid (EPA)□
Elongated to docosahexanoic acid (DHA)□
§
EPA and arachidonic acid make eicosanoids
Hormone-like substances that regulate blood clotting,
immune system, inflammation, and blood pressure
□
§
ALA is needed to make healthy cell membranes, particularly in the
nerve tissues and retina
§
○
Liver uses cholesterol as starting material for: hormones, bile, and vitamin
D
Remember list of functions of cholesterol
Precursor for vitamin d, sex steroids (hormones like estrogen
and testosterone) and adrenal corticoids
□
§
○
Phospholipids and cholesterol make up cell membranes
Phospholipids: part of phospholipid bilayer in cell membrane
§
Cholesterol: structural component in cell membranes
§
○
-
Recommendations for daily intake of triglycerides and cholesterol?
Type of fat must be considered
○
ADMR: 20-35% total cals should be fat
○
Excess fat doesn't lead to weight gain unless excess cals
But fat is made up of concentrated cals (9 cals/ g) so eat more fat,
more cals, so can result in weight gain
§
○
For heart health:
No more than 10% of total cals from saturated fat (<7% of total cals
is ideal)
§
Replace saturated fats w/ monosaturated and polysaturated fats)
§
Limit trans fats to <1% of totals cals
§
○
Essential fatty acids have specific recommendations
ADMR for the essential fatty acids
Linoleic acid
5-10% of total cals
®
□
Alpha-linolenic acid
0.6 - 1.2% of total cals
®
□
For people diagnosed w/ heart disease:
Consume 1 gram of essential fatty acids each day
®
2-4 grams of EPA and DHA daily may reduce blood
triglycerides
®
□
§
○
Dietary cholesterol and phospholipids are not essential
The liver synthesizes cholesterol needed by the body
About 900 mg/dl□
Liver decreases synthesis based on dietary intake□
Total cholesterol levels in the blood are maintained by a
feedback system
□
§
To reduce risk of cardiovascular disease, dietary cholesterol should
be limited <300 mg/dl
§
Lecithin is the most common dietary phospholipid in the diet
Liver makes all phospholipids, including lecithin, that the body
needs
□
Lecithin is digested in GI tract and does not enter the small
intestinal cell intact
□
§
Lecithin supplements do not offer any health benefits as claimed by
supplement companies
Claims include weight loss, improving fat metabolism,
cardiovascular health, and exercise performance
□
§
○
-
Best food sources are low in saturated fat
To replace or lower saturated fats w/ unsaturated fats, consume:
Vegetable oils: soybean, corn, canola oils
§
Soybeans
§
Walnuts, flaxseeds, wheat germ
§
○
Increase alpha-linolenic acid (omega-3 fatty acids) by consuming:
Walnuts, flaxseeds, canola oil
§
Fatty fish such as salmon, tuna, mackerel
All fish have EPA and DHA□
§
Avoid cod-liver oil, b/c it is very high in vitamin A, which can be
detrimental
§
It is impossible to eliminate all saturated fat from the diet
§
Primary saturated fat sources
Animal foods: fatty cuts of meat, whole-milk dairy products,
and skin on poultry
□
Plant sources: coconut, palm, and palm kernel oils□
§
○
Tips for lowering saturated fats:
Limit intake of foods rich in saturated fat
§
Consume lower fat-containing foods
§
Read the Nutrition Facts panel to help you choose foods that are
low in fat
§
○
Reduce foods that contain Trans Fat and Cholesterol
Saturated fats fro animal and plant sources were used in home
cooking and commercial food preparation to:
Provide a rich flaky texture to baked goods□
Decrease the incidence of rancidity □
§
Later, hydrogenated oils and trans fats were used b/c they
performed a similar function w/o adding cholesterol to the diet
§
○
-
Foods w/ Trans Fats
Hydrogenation: replacing saturated w/ hydrogenated fat
○
During hydrogenation process, some of double bonds are reconfigured
The unstable cis fatty acids in the double bond form trans fatty
acids
§
○
Some trans fats are naturally occurring
○
Trans fat may actually be worse for heart health than are saturated fats
Raise LDL and lower HDL cholesterol
§
○
FDA requires trans fats to be listed on food labels
○
-
Cholesterol and Plant Sterols
Dietary cholesterol comes mainly from animal products
○
The cholesterol produced in plant cell walls and oils is so minimal they are
considered cholesterol free
○
Phytosterols and stanols
Lower LDL levels by competing w/ cholesterol for absorption
§
Found in soybean oil, many fruits, vegetables, legumes, sesame
seeds, cereals, and other plant foods
§
Food manufactures are fortifying foods w/ them to help lower
cholesterol
§
○
-
Fat Substitutes Lower Fat in Foods
A research survey found that over 160 million Americans (79% of adult
population) chose lower-fat foods and beverages
Health concerns are major reason
§
○
Lower-fat foods contain fat substitutes
Designed to provide creamy properties of fat for fewer cals and
total fat grams
§
3 categories of fat substitutes
§
○
-
Carb-, Protein-, or Fat-Based Substitutes
Carb-based
Majority of fat substitutes
§
Use plant polysaccharides to help retain moisture and provide
fatlike texture
§
○
Protein-based
Created from protein in eggs and milk
§
Provide a creamy texture in mouth
§
○
Fat-based
Modified fats that provide the physical attributes of fat for fewer
cals than regular fat or interfere w/ absorption of fat
§
○
Overconsumption of cals from regular, low-fat, or fat-free products can
lead to weight gain
○
-
What is Heart Disease and What Factors Increase Risk?
Cardiovascular disease (CVD): encompasses disorders of cardiovascular
system, including heart
○
#1 killer of adults in US
○
Begins w/ atherosclerosis: arteries leading to the brain can cause a stroke
The progression:
Injury to lining of arteries promotes inflammation□
LDLs and other lipid substances accumulate at the injured site
and become oxidized by reacting w/ free radicals and metal
ions
□
Macrophages are attracted to the oxidized LDLs and then
form plaques
□
§
Primary risk factor is elevated blood lipids
§
Starting at 20, have a blood lipid profile analysis every 5 years
§
Measure cholesterol-to-HDL ratio
§
Have a risk score calculated
§
Consume less saturated and trans fats and moderate cholesterol
intake
Diets high in saturated fats raise LDLs in the blood□
High-cholesterol diet does not affect LDLs □
Type of saturated fat may have a greater impact on LDL levels
in the blood
Myristic and palmitic acids raise LDLs
®
Stearic acid doesn't raise LDLs
®
It is difficult to isolate foods by saturated fatty acid
type, recommended lowering overall saturated fatty
acid intake
®
□
Trans fats raise LDLs and blood triglycerides, and lower HDLs□
§
○
-
Eat More Fish and Plant Foods
Eat at least 2, 3.5 oz servings of fatty fish rich in omega-3 fatty acids
(alpha-linoleic acid)/ week
Baked, broiled, or poached
§
Limit consumption of EPA and DHA to 3 or less grams/ day
Increased risk for excessive bleeding□
May raise both blood glucose and LDL levels□
Intakes >3g occur only w/ supplementation□
Omega-3 fatty acid supplements should be taken w/ medical
supervision
□
§
Children and pregnant women should consume no more than 12 oz
of fatty fish/ week
§
Consume more plant foods
Canola oil, soy, flaxseeds, and walnuts are rich in ALA□
Choose plant foods rich in soluble fiber□
Consume at least 2 grams of plant sterols a day
Shown to lower LDL levels by 10%
®
Food rich in plant sterols include soybean oil, many
fruits, vegetables, legumes, nuts, and other plant foods
as well as margarine made w/ plant sterols
®
□
§
○
-
Consume Antioxidants and Phytochemicals
Antioxidants and phytochemicals neutralize free radicals, stimulate
immune system to repair tissue damage, and reduce heart disease risk
Vitamin E, vitamin C, and beta-carotene
§
Garlic may help lower cholesterol
§
Flavonoids may help LDLs from oxidizing
§
Nuts reduce LDL levels
§
○
-
Get Plenty of Exercise, Manage Your Weight, and Quit Smoking
Exercise raises HDLs (good cholesterol), lowers LDLs, and reduces high
blood pressure and insulin resistance
○
Aim for 30 minutes or more moderate exercise a day
○
Quit smoking
Smoking damages walls of arteries and accelerates atherosclerosis
§
Smokers are 3x more likely to have a heart attack than nonsmokers
§
○
-
A Word about Protective Effects of Red Wine and Alcohol
Alcohol, in moderate amounts, can reduce the risk of heart disease,
mainly in middle-aged adults
Increases HDL levels
§
Decreases blood clotting
§
○
Moderate amounts are defined as no more than:
1 serving of alc/ day for females
§
2 servings of alc/ day for males
§
○
-
NUTR 2015 Chpt. 5: Lipids
Wednesday, February 7, 2018
2:00 PM
What are lipids and how differ in structure ?
Lipids refer to a category of compounds that include:
Triglycerides
§
Phospholipids
§
Sterols
§
○
Contain C, O, and H (same structure as carbs except…)
○
Hydrophobic, which means they don't dissolve in water
○
Basic functions in body
Store and provide energy
§
Provide insulation
§
Help manufacture steroids and bile
§
Play a role in transporting fat-soluble nutrients in the blood
§
Used to manufacture sex hormones
§
Key to the structure of cell membranes
§
○
Many lipids are comprised of fatty acids
Building blocks of triglycerides and phospholipids
§
Chain of C and h atoms w/ a carboxyl group at the alpha end and a
methyl group at the omega end
§
Fat has more cals (9) then carbs or proteins (4) b/c of higher ratio of
C and H to O
§
4 types of fatty acids which vary by
Length of carbon chain
2 to 80 carbons long
Most common 12 to 24 carbons
◊
®
Short-chain fatty chains
2-4 carbons
◊
®
Medium-chain fatty acids
6-10 carbons
◊
®
Long-chain fatty acids
12 or more carbons
◊
Most common type in foods and take longer to
digest than short or medium-chain fatty acids
◊
®
□
Degree of saturation
Determined by whether carbons are held together by a
single or double bond
®
Saturated fatty acids
All carbons on fatty acid bound to hydrogen
◊
No double bonds
◊
Solid at room temp
◊
Have a higher melting point
◊
®
Unsaturated fatty acids
Some carbons on fatty acid form a double bond
/w each other instead of binding to hydrogen
◊
Tend to be liquid at room temp
◊
Have a lower melting temp
◊
Monounsaturated fatty acid (MUFA)
Has one double bond
}
◊
Polyunsaturated fatty acid (PUFA)
Has 2 or more double bonds
}
◊
®
□
Stability of fatty acids
Rancidity: spoiling of fats through oxidation
Double bonds are less stable than single bonds
◊
Foods w/ unsaturated fats become rancid faster
than foods w/ saturated fats (b/c have double
bonds)
◊
Manufacturers have enhance the stability of fatty
acids by:
Adding antioxidants
}
Limiting food exposure to oxygen, heat, and
light
}
Hydrogenation
}
◊
®
Location of double bond
Location of first double bond from methyl (or
omega) end of unsaturated fatty acids affects
properties of fatty acids
Omega-3 fatty acid
First double bond is b/w 3rd and 4th
carbons from omega end
–
Ex. Alpha-linolenic acid
–
}
Omega-6 fatty acid
First double bond is b/w 6th and 7th
carbons from omega end
–
Ex. Linoleic acid
–
}
◊
®
□
Shape
Unsaturated fatty acids form 2 diff shapes based on the
position of the H atoms around the double bond
®
□
§
○
Triglycerides are the most common lipid
Make up about 95% of lipids in foods
§
Has 3 fatty acids connected to a glycerol backbone (like upper case
E)
§
Functions
Add texture to baked goods□
Makes meat tender□
Preserve freshness□
Stored as adipose tissue for energy□
However: high level in blood are risk factor for heart disease□
§
○
Phospholipids
Differ from triglycerides b/c while made of a glycerol backbone, 2
fatty acids, a phosphate group, and diff nitrogen-containing
compounds
Lecithin (aka phosphatidylcholine) is a type of phospholipid
Synthesized by liver
®
Functions:
Use as an emulsifier in food (ex. Salad dressing,
bile, etc.)
◊
A major phospholipid in cell membrane
◊
®
□
§
Hydrophilic on one end; hydrophobic on the other
§
Make up the phospholipid bilayer in the cell membrane
§
○
Sterols are more complex than triglycerides
Made of 4 connecting rings of carbon and hydrogen
Do not contain glycerol or fatty acids□
They do not provide energy□
§
Cholesterol is the best known sterol
Found in every cell in the body□
Helps w/ numerous body processes□
Precursor to vitamin D, sex steroids, and adrenal corticoids □
§
Phytosterols and phytostanols are major plant sterols
§
○
-
How are lipids digested, absorbed, and transported?
Lipids from food primarily in the form of triglycerides
Lesser extent phospholipids and sterols
§
○
During digestion, fatty acids form a combination of free fatty acids,
glycerol, and monoglycerides
○
Lipases are the enzymes that digest lipids
○
Digestion begins in mouth w/ chewing
Mixes w/ saliva and lingual lipase
Lingual lipase hydrolyzes the medium-chain fatty acids□
§
○
The bolus of food travels through the esophagus into the stomach
Stomach muscles
§
Gastrin is released from gastric pits lining stomach and stimulates
release of gastric juices, rich in gastric lipase
§
Gastric lipase hydrolyzes one fatty acid from the triglyceride, which
produces a free fatty acid and a diglyceride
§
○
Most triglycerides are digested and their components are absorbed in the
small intestine
Fat globules in chyme tend to cluster together
§
In the intestine, bile acid emulsifies larger fat droplets into smaller
fat droplets
This allows pancreatic lipase to digest the lipids easily (which
is the enzyme responsible for the majority of lipid digestion)
□
The resulting lipid complex is micelle (clusters of fatty acids,
monoglycerides, and other lipids surrounded by bile salts that
transport lipids across the cell membrane of the villi)
Transport the lipid complex across the small intestinal
wall
®
□
§
Cholecystokinin (CCK) is the hormone that stimulates the
gallbladder to release bile acid
CCK is released by cells of duodenum in presence of lipids□
§
Phospholipids
Emulsified by bile during digestion□
Dismantled into 2 free fatty acids and phospholipid remnant□
Packaged as micelles□
Transported through intestinal wall□
§
Sterols
Not digested□
Carried by micelle and absorbed intact through intestinal wall□
Bile emulsifies sterols□
§
If lipids are undigested and not absorbed in small intestine:
Bind w/ fiber□
Are eliminated in feces □
§
○
Chylomicrons facilitate lipid absorption
Lipids are absorbed based on structure
Glycerol and short to medium-chain fatty acids are absorbed
directly into bloodstream
□
Long-chain fatty acids combine w/ phospholipids and
cholesterol to form chylomicrons
□
§
Chylomicrons are too large to be absorbed directly into the
bloodstream
Travel through lymph fluid first□
Exit the lymph and enter bloodstream through thoracic duct
next to heart
□
Lipoprotein lipase (LPL) hydrolyzes triglycerides in the
chylomicrons as they travel to the liver via bloodstream
□
Not made in liver**□
§
○
Lipoproteins transport lipids
4 kinds of lipoproteins that carry lipids through circulatory system
Chylomicrons□
Very-low-density lipoproteins (VLDLs)
Transport triglycerides (TGs) and cholesterol from the
liver to the cells
®
Lipoprotein lipase located on the outside of adipocytes
and muscle cells cleave fatty acids (FAs) from TGs
FAs move into adipocytes and muscle cells and
stored for later use
◊
Increases ratio of protein to lipids
◊
Process converts VLDLs to LDLs
◊
®
□
Low-density lipoproteins (LDLs)
Carry cholesterol from the liver to the tissues
®
"bad cholesterol"
®
"lousy" DLs
®
□
High-density lipoproteins (HDLs)
Carry cholesterol from the cells to the liver
®
"good cholesterol"
®
"healthy" DLs
®
□
§
VLDLs, LDLs, and HDLs
Globular molecule w/ a lipid center surrounded by a plasma
membrane
□
Density determines function□
More protein= high density □
HDL and LDL biomarkers are used to determine the health of
arteries
□
§
○
-
What are the functions of lipids in the body
Several critical roles in the body
Source of energy
Fatty acids provide a concentrated source of cals
9 cals/ g
®
□
Readily available when body needs energy□
Body's main source of energy throughout day□
Excess fat is stored
Body has unlimited ability to store excess energy as fat
in adipocytes
Fat cells can grow up to 1,000 times their original
size
◊
Additional fat cells are made when fat stores are
filled
◊
®
Some fat is stored in muscle cells
®
□
Fats are a powerful fuel source
Preferred by heart, liver, and resting muscle
®
Spares glucose so it is the only used by CNS and red
blood cells
®
Provides a backup source of energy b/w meals
®
Cannot sustain life during prolonged starvation
Glucose is needed to metabolize fat
◊
The glycerol protein of fat can make small
amounts of glucose
◊
®
□
§
Form body structures (including cell membranes)
§
Regulate metabolism
§
Enhance the absorption of fat-soluble vitamins
Dietary fat aids in absorption of lipid compounds
Several essential nutrients require dietary fat for
absorption
Fat-soluble vitamins
◊
Carotenoids
◊
Cholesterol
◊
Phospholipids
◊
®
Twenty grams/ day needed to stimulate chylomicrons
that transport fat-soluble vitamins
®
□
§
Provide a layer of insulation to help regulate body temp
Fat in subcutaneous tissue
Insulates body
®
Maintain body temp
®
□
Fat protects bones and vital organs from trauma□
Too much stored fat can be detrimental to health and
increase risk for heart disease, hypertension and diabetes
□
§
Help cushion major organs
§
○
Essential fatty acids manufacture eicosanoids (made via the oxidation of
polyunsaturated fats and are involved in cellular activity, also noted for
role in inflammation) and cell membranes
Linoleic acid
Converted to arachidonic acid□
§
Alpha-linolenic acid (ALA)
Converted to eicosapentanoic acid (EPA)□
Elongated to docosahexanoic acid (DHA)□
§
EPA and arachidonic acid make eicosanoids
Hormone-like substances that regulate blood clotting,
immune system, inflammation, and blood pressure
□
§
ALA is needed to make healthy cell membranes, particularly in the
nerve tissues and retina
§
○
Liver uses cholesterol as starting material for: hormones, bile, and vitamin
D
Remember list of functions of cholesterol
Precursor for vitamin d, sex steroids (hormones like estrogen
and testosterone) and adrenal corticoids
□
§
○
Phospholipids and cholesterol make up cell membranes
Phospholipids: part of phospholipid bilayer in cell membrane
§
Cholesterol: structural component in cell membranes
§
○
-
Recommendations for daily intake of triglycerides and cholesterol?
Type of fat must be considered
○
ADMR: 20-35% total cals should be fat
○
Excess fat doesn't lead to weight gain unless excess cals
But fat is made up of concentrated cals (9 cals/ g) so eat more fat,
more cals, so can result in weight gain
§
○
For heart health:
No more than 10% of total cals from saturated fat (<7% of total cals
is ideal)
§
Replace saturated fats w/ monosaturated and polysaturated fats)
§
Limit trans fats to <1% of totals cals
§
○
Essential fatty acids have specific recommendations
ADMR for the essential fatty acids
Linoleic acid
5-10% of total cals
®
□
Alpha-linolenic acid
0.6 - 1.2% of total cals
®
□
For people diagnosed w/ heart disease:
Consume 1 gram of essential fatty acids each day
®
2-4 grams of EPA and DHA daily may reduce blood
triglycerides
®
□
§
○
Dietary cholesterol and phospholipids are not essential
The liver synthesizes cholesterol needed by the body
About 900 mg/dl□
Liver decreases synthesis based on dietary intake□
Total cholesterol levels in the blood are maintained by a
feedback system
□
§
To reduce risk of cardiovascular disease, dietary cholesterol should
be limited <300 mg/dl
§
Lecithin is the most common dietary phospholipid in the diet
Liver makes all phospholipids, including lecithin, that the body
needs
□
Lecithin is digested in GI tract and does not enter the small
intestinal cell intact
□
§
Lecithin supplements do not offer any health benefits as claimed by
supplement companies
Claims include weight loss, improving fat metabolism,
cardiovascular health, and exercise performance
□
§
○
-
Best food sources are low in saturated fat
To replace or lower saturated fats w/ unsaturated fats, consume:
Vegetable oils: soybean, corn, canola oils
§
Soybeans
§
Walnuts, flaxseeds, wheat germ
§
○
Increase alpha-linolenic acid (omega-3 fatty acids) by consuming:
Walnuts, flaxseeds, canola oil
§
Fatty fish such as salmon, tuna, mackerel
All fish have EPA and DHA□
§
Avoid cod-liver oil, b/c it is very high in vitamin A, which can be
detrimental
§
It is impossible to eliminate all saturated fat from the diet
§
Primary saturated fat sources
Animal foods: fatty cuts of meat, whole-milk dairy products,
and skin on poultry
□
Plant sources: coconut, palm, and palm kernel oils□
§
○
Tips for lowering saturated fats:
Limit intake of foods rich in saturated fat
§
Consume lower fat-containing foods
§
Read the Nutrition Facts panel to help you choose foods that are
low in fat
§
○
Reduce foods that contain Trans Fat and Cholesterol
Saturated fats fro animal and plant sources were used in home
cooking and commercial food preparation to:
Provide a rich flaky texture to baked goods□
Decrease the incidence of rancidity □
§
Later, hydrogenated oils and trans fats were used b/c they
performed a similar function w/o adding cholesterol to the diet
§
○
-
Foods w/ Trans Fats
Hydrogenation: replacing saturated w/ hydrogenated fat
○
During hydrogenation process, some of double bonds are reconfigured
The unstable cis fatty acids in the double bond form trans fatty
acids
§
○
Some trans fats are naturally occurring
○
Trans fat may actually be worse for heart health than are saturated fats
Raise LDL and lower HDL cholesterol
§
○
FDA requires trans fats to be listed on food labels
○
-
Cholesterol and Plant Sterols
Dietary cholesterol comes mainly from animal products
○
The cholesterol produced in plant cell walls and oils is so minimal they are
considered cholesterol free
○
Phytosterols and stanols
Lower LDL levels by competing w/ cholesterol for absorption
§
Found in soybean oil, many fruits, vegetables, legumes, sesame
seeds, cereals, and other plant foods
§
Food manufactures are fortifying foods w/ them to help lower
cholesterol
§
○
-
Fat Substitutes Lower Fat in Foods
A research survey found that over 160 million Americans (79% of adult
population) chose lower-fat foods and beverages
Health concerns are major reason
§
○
Lower-fat foods contain fat substitutes
Designed to provide creamy properties of fat for fewer cals and
total fat grams
§
3 categories of fat substitutes
§
○
-
Carb-, Protein-, or Fat-Based Substitutes
Carb-based
Majority of fat substitutes
§
Use plant polysaccharides to help retain moisture and provide
fatlike texture
§
○
Protein-based
Created from protein in eggs and milk
§
Provide a creamy texture in mouth
§
○
Fat-based
Modified fats that provide the physical attributes of fat for fewer
cals than regular fat or interfere w/ absorption of fat
§
○
Overconsumption of cals from regular, low-fat, or fat-free products can
lead to weight gain
○
-
What is Heart Disease and What Factors Increase Risk?
Cardiovascular disease (CVD): encompasses disorders of cardiovascular
system, including heart
○
#1 killer of adults in US
○
Begins w/ atherosclerosis: arteries leading to the brain can cause a stroke
The progression:
Injury to lining of arteries promotes inflammation□
LDLs and other lipid substances accumulate at the injured site
and become oxidized by reacting w/ free radicals and metal
ions
□
Macrophages are attracted to the oxidized LDLs and then
form plaques
□
§
Primary risk factor is elevated blood lipids
§
Starting at 20, have a blood lipid profile analysis every 5 years
§
Measure cholesterol-to-HDL ratio
§
Have a risk score calculated
§
Consume less saturated and trans fats and moderate cholesterol
intake
Diets high in saturated fats raise LDLs in the blood□
High-cholesterol diet does not affect LDLs □
Type of saturated fat may have a greater impact on LDL levels
in the blood
Myristic and palmitic acids raise LDLs
®
Stearic acid doesn't raise LDLs
®
It is difficult to isolate foods by saturated fatty acid
type, recommended lowering overall saturated fatty
acid intake
®
□
Trans fats raise LDLs and blood triglycerides, and lower HDLs□
§
○
-
Eat More Fish and Plant Foods
Eat at least 2, 3.5 oz servings of fatty fish rich in omega-3 fatty acids
(alpha-linoleic acid)/ week
Baked, broiled, or poached
§
Limit consumption of EPA and DHA to 3 or less grams/ day
Increased risk for excessive bleeding□
May raise both blood glucose and LDL levels□
Intakes >3g occur only w/ supplementation□
Omega-3 fatty acid supplements should be taken w/ medical
supervision
□
§
Children and pregnant women should consume no more than 12 oz
of fatty fish/ week
§
Consume more plant foods
Canola oil, soy, flaxseeds, and walnuts are rich in ALA□
Choose plant foods rich in soluble fiber□
Consume at least 2 grams of plant sterols a day
Shown to lower LDL levels by 10%
®
Food rich in plant sterols include soybean oil, many
fruits, vegetables, legumes, nuts, and other plant foods
as well as margarine made w/ plant sterols
®
□
§
○
-
Consume Antioxidants and Phytochemicals
Antioxidants and phytochemicals neutralize free radicals, stimulate
immune system to repair tissue damage, and reduce heart disease risk
Vitamin E, vitamin C, and beta-carotene
§
Garlic may help lower cholesterol
§
Flavonoids may help LDLs from oxidizing
§
Nuts reduce LDL levels
§
○
-
Get Plenty of Exercise, Manage Your Weight, and Quit Smoking
Exercise raises HDLs (good cholesterol), lowers LDLs, and reduces high
blood pressure and insulin resistance
○
Aim for 30 minutes or more moderate exercise a day
○
Quit smoking
Smoking damages walls of arteries and accelerates atherosclerosis
§
Smokers are 3x more likely to have a heart attack than nonsmokers
§
○
-
A Word about Protective Effects of Red Wine and Alcohol
Alcohol, in moderate amounts, can reduce the risk of heart disease,
mainly in middle-aged adults
Increases HDL levels
§
Decreases blood clotting
§
○
Moderate amounts are defined as no more than:
1 serving of alc/ day for females
§
2 servings of alc/ day for males
§
○
-
NUTR 2015 Chpt. 5: Lipids
Wednesday, February 7, 2018 2:00 PM
What are lipids and how differ in structure ?
Lipids refer to a category of compounds that include:
Triglycerides
§
Phospholipids
§
Sterols
§
○
Contain C, O, and H (same structure as carbs except…)
○
Hydrophobic, which means they don't dissolve in water
○
Basic functions in body
Store and provide energy
§
Provide insulation
§
Help manufacture steroids and bile
§
Play a role in transporting fat-soluble nutrients in the blood
§
Used to manufacture sex hormones
§
Key to the structure of cell membranes
§
○
Many lipids are comprised of fatty acids
Building blocks of triglycerides and phospholipids
§
Chain of C and h atoms w/ a carboxyl group at the alpha end and a
methyl group at the omega end
§
Fat has more cals (9) then carbs or proteins (4) b/c of higher ratio of
C and H to O
§
4 types of fatty acids which vary by
Length of carbon chain
2 to 80 carbons long
Most common 12 to 24 carbons
◊
®
Short-chain fatty chains
2-4 carbons
◊
®
Medium-chain fatty acids
6-10 carbons
◊
®
Long-chain fatty acids
12 or more carbons
◊
Most common type in foods and take longer to
digest than short or medium-chain fatty acids
◊
®
□
Degree of saturation
Determined by whether carbons are held together by a
single or double bond
®
Saturated fatty acids
All carbons on fatty acid bound to hydrogen
◊
No double bonds
◊
Solid at room temp
◊
Have a higher melting point
◊
®
Unsaturated fatty acids
Some carbons on fatty acid form a double bond
/w each other instead of binding to hydrogen
◊
Tend to be liquid at room temp
◊
Have a lower melting temp
◊
Monounsaturated fatty acid (MUFA)
Has one double bond
}
◊
Polyunsaturated fatty acid (PUFA)
Has 2 or more double bonds
}
◊
®
□
Stability of fatty acids
Rancidity: spoiling of fats through oxidation
Double bonds are less stable than single bonds
◊
Foods w/ unsaturated fats become rancid faster
than foods w/ saturated fats (b/c have double
bonds)
◊
Manufacturers have enhance the stability of fatty
acids by:
Adding antioxidants
}
Limiting food exposure to oxygen, heat, and
light
}
Hydrogenation
}
◊
®
Location of double bond
Location of first double bond from methyl (or
omega) end of unsaturated fatty acids affects
properties of fatty acids
Omega-3 fatty acid
First double bond is b/w 3rd and 4th
carbons from omega end
–
Ex. Alpha-linolenic acid
–
}
Omega-6 fatty acid
First double bond is b/w 6th and 7th
carbons from omega end
–
Ex. Linoleic acid
–
}
◊
®
□
Shape
Unsaturated fatty acids form 2 diff shapes based on the
position of the H atoms around the double bond
®
□
§
○
Triglycerides are the most common lipid
Make up about 95% of lipids in foods
§
Has 3 fatty acids connected to a glycerol backbone (like upper case
E)
§
Functions
Add texture to baked goods
□
Makes meat tender
□
Preserve freshness
□
Stored as adipose tissue for energy
□
However: high level in blood are risk factor for heart disease
□
§
○
Phospholipids
Differ from triglycerides b/c while made of a glycerol backbone, 2
fatty acids, a phosphate group, and diff nitrogen-containing
compounds
Lecithin (aka phosphatidylcholine) is a type of phospholipid
Synthesized by liver
®
Functions:
Use as an emulsifier in food (ex. Salad dressing,
bile, etc.)
◊
A major phospholipid in cell membrane
◊
®
□
§
Hydrophilic on one end; hydrophobic on the other
§
Make up the phospholipid bilayer in the cell membrane
§
○
Sterols are more complex than triglycerides
Made of 4 connecting rings of carbon and hydrogen
Do not contain glycerol or fatty acids
□
They do not provide energy
□
§
Cholesterol is the best known sterol
Found in every cell in the body
□
Helps w/ numerous body processes
□
Precursor to vitamin D, sex steroids, and adrenal corticoids
□
§
Phytosterols and phytostanols are major plant sterols
§
○
-
How are lipids digested, absorbed, and transported?
Lipids from food primarily in the form of triglycerides
Lesser extent phospholipids and sterols
§
○
During digestion, fatty acids form a combination of free fatty acids,
glycerol, and monoglycerides
○
Lipases are the enzymes that digest lipids
○
Digestion begins in mouth w/ chewing
Mixes w/ saliva and lingual lipase
Lingual lipase hydrolyzes the medium-chain fatty acids□
§
○
The bolus of food travels through the esophagus into the stomach
Stomach muscles
§
Gastrin is released from gastric pits lining stomach and stimulates
release of gastric juices, rich in gastric lipase
§
Gastric lipase hydrolyzes one fatty acid from the triglyceride, which
produces a free fatty acid and a diglyceride
§
○
Most triglycerides are digested and their components are absorbed in the
small intestine
Fat globules in chyme tend to cluster together
§
In the intestine, bile acid emulsifies larger fat droplets into smaller
fat droplets
This allows pancreatic lipase to digest the lipids easily (which
is the enzyme responsible for the majority of lipid digestion)
□
The resulting lipid complex is micelle (clusters of fatty acids,
monoglycerides, and other lipids surrounded by bile salts that
transport lipids across the cell membrane of the villi)
Transport the lipid complex across the small intestinal
wall
®
□
§
Cholecystokinin (CCK) is the hormone that stimulates the
gallbladder to release bile acid
CCK is released by cells of duodenum in presence of lipids□
§
Phospholipids
Emulsified by bile during digestion□
Dismantled into 2 free fatty acids and phospholipid remnant□
Packaged as micelles□
Transported through intestinal wall□
§
Sterols
Not digested□
Carried by micelle and absorbed intact through intestinal wall□
Bile emulsifies sterols□
§
If lipids are undigested and not absorbed in small intestine:
Bind w/ fiber□
Are eliminated in feces □
§
○
Chylomicrons facilitate lipid absorption
Lipids are absorbed based on structure
Glycerol and short to medium-chain fatty acids are absorbed
directly into bloodstream
□
Long-chain fatty acids combine w/ phospholipids and
cholesterol to form chylomicrons
□
§
Chylomicrons are too large to be absorbed directly into the
bloodstream
Travel through lymph fluid first□
Exit the lymph and enter bloodstream through thoracic duct
next to heart
□
Lipoprotein lipase (LPL) hydrolyzes triglycerides in the
chylomicrons as they travel to the liver via bloodstream
□
Not made in liver**□
§
○
Lipoproteins transport lipids
4 kinds of lipoproteins that carry lipids through circulatory system
Chylomicrons□
Very-low-density lipoproteins (VLDLs)
Transport triglycerides (TGs) and cholesterol from the
liver to the cells
®
Lipoprotein lipase located on the outside of adipocytes
and muscle cells cleave fatty acids (FAs) from TGs
FAs move into adipocytes and muscle cells and
stored for later use
◊
Increases ratio of protein to lipids
◊
Process converts VLDLs to LDLs
◊
®
□
Low-density lipoproteins (LDLs)
Carry cholesterol from the liver to the tissues
®
"bad cholesterol"
®
"lousy" DLs
®
□
High-density lipoproteins (HDLs)
Carry cholesterol from the cells to the liver
®
"good cholesterol"
®
"healthy" DLs
®
□
§
VLDLs, LDLs, and HDLs
Globular molecule w/ a lipid center surrounded by a plasma
membrane
□
Density determines function□
More protein= high density □
HDL and LDL biomarkers are used to determine the health of
arteries
□
§
○
-
What are the functions of lipids in the body
Several critical roles in the body
Source of energy
Fatty acids provide a concentrated source of cals
9 cals/ g
®
□
Readily available when body needs energy□
Body's main source of energy throughout day□
Excess fat is stored
Body has unlimited ability to store excess energy as fat
in adipocytes
Fat cells can grow up to 1,000 times their original
size
◊
Additional fat cells are made when fat stores are
filled
◊
®
Some fat is stored in muscle cells
®
□
Fats are a powerful fuel source
Preferred by heart, liver, and resting muscle
®
Spares glucose so it is the only used by CNS and red
blood cells
®
Provides a backup source of energy b/w meals
®
Cannot sustain life during prolonged starvation
Glucose is needed to metabolize fat
◊
The glycerol protein of fat can make small
amounts of glucose
◊
®
□
§
Form body structures (including cell membranes)
§
Regulate metabolism
§
Enhance the absorption of fat-soluble vitamins
Dietary fat aids in absorption of lipid compounds
Several essential nutrients require dietary fat for
absorption
Fat-soluble vitamins
◊
Carotenoids
◊
Cholesterol
◊
Phospholipids
◊
®
Twenty grams/ day needed to stimulate chylomicrons
that transport fat-soluble vitamins
®
□
§
Provide a layer of insulation to help regulate body temp
Fat in subcutaneous tissue
Insulates body
®
Maintain body temp
®
□
Fat protects bones and vital organs from trauma□
Too much stored fat can be detrimental to health and
increase risk for heart disease, hypertension and diabetes
□
§
Help cushion major organs
§
○
Essential fatty acids manufacture eicosanoids (made via the oxidation of
polyunsaturated fats and are involved in cellular activity, also noted for
role in inflammation) and cell membranes
Linoleic acid
Converted to arachidonic acid□
§
Alpha-linolenic acid (ALA)
Converted to eicosapentanoic acid (EPA)□
Elongated to docosahexanoic acid (DHA)□
§
EPA and arachidonic acid make eicosanoids
Hormone-like substances that regulate blood clotting,
immune system, inflammation, and blood pressure
□
§
ALA is needed to make healthy cell membranes, particularly in the
nerve tissues and retina
§
○
Liver uses cholesterol as starting material for: hormones, bile, and vitamin
D
Remember list of functions of cholesterol
Precursor for vitamin d, sex steroids (hormones like estrogen
and testosterone) and adrenal corticoids
□
§
○
Phospholipids and cholesterol make up cell membranes
Phospholipids: part of phospholipid bilayer in cell membrane
§
Cholesterol: structural component in cell membranes
§
○
-
Recommendations for daily intake of triglycerides and cholesterol?
Type of fat must be considered
○
ADMR: 20-35% total cals should be fat
○
Excess fat doesn't lead to weight gain unless excess cals
But fat is made up of concentrated cals (9 cals/ g) so eat more fat,
more cals, so can result in weight gain
§
○
For heart health:
No more than 10% of total cals from saturated fat (<7% of total cals
is ideal)
§
Replace saturated fats w/ monosaturated and polysaturated fats)
§
Limit trans fats to <1% of totals cals
§
○
Essential fatty acids have specific recommendations
ADMR for the essential fatty acids
Linoleic acid
5-10% of total cals
®
□
Alpha-linolenic acid
0.6 - 1.2% of total cals
®
□
For people diagnosed w/ heart disease:
Consume 1 gram of essential fatty acids each day
®
2-4 grams of EPA and DHA daily may reduce blood
triglycerides
®
□
§
○
Dietary cholesterol and phospholipids are not essential
The liver synthesizes cholesterol needed by the body
About 900 mg/dl□
Liver decreases synthesis based on dietary intake□
Total cholesterol levels in the blood are maintained by a
feedback system
□
§
To reduce risk of cardiovascular disease, dietary cholesterol should
be limited <300 mg/dl
§
Lecithin is the most common dietary phospholipid in the diet
Liver makes all phospholipids, including lecithin, that the body
needs
□
Lecithin is digested in GI tract and does not enter the small
intestinal cell intact
□
§
Lecithin supplements do not offer any health benefits as claimed by
supplement companies
Claims include weight loss, improving fat metabolism,
cardiovascular health, and exercise performance
□
§
○
-
Best food sources are low in saturated fat
To replace or lower saturated fats w/ unsaturated fats, consume:
Vegetable oils: soybean, corn, canola oils
§
Soybeans
§
Walnuts, flaxseeds, wheat germ
§
○
Increase alpha-linolenic acid (omega-3 fatty acids) by consuming:
Walnuts, flaxseeds, canola oil
§
Fatty fish such as salmon, tuna, mackerel
All fish have EPA and DHA□
§
Avoid cod-liver oil, b/c it is very high in vitamin A, which can be
detrimental
§
It is impossible to eliminate all saturated fat from the diet
§
Primary saturated fat sources
Animal foods: fatty cuts of meat, whole-milk dairy products,
and skin on poultry
□
Plant sources: coconut, palm, and palm kernel oils□
§
○
Tips for lowering saturated fats:
Limit intake of foods rich in saturated fat
§
Consume lower fat-containing foods
§
Read the Nutrition Facts panel to help you choose foods that are
low in fat
§
○
Reduce foods that contain Trans Fat and Cholesterol
Saturated fats fro animal and plant sources were used in home
cooking and commercial food preparation to:
Provide a rich flaky texture to baked goods□
Decrease the incidence of rancidity □
§
Later, hydrogenated oils and trans fats were used b/c they
performed a similar function w/o adding cholesterol to the diet
§
○
-
Foods w/ Trans Fats
Hydrogenation: replacing saturated w/ hydrogenated fat
○
During hydrogenation process, some of double bonds are reconfigured
The unstable cis fatty acids in the double bond form trans fatty
acids
§
○
Some trans fats are naturally occurring
○
Trans fat may actually be worse for heart health than are saturated fats
Raise LDL and lower HDL cholesterol
§
○
FDA requires trans fats to be listed on food labels
○
-
Cholesterol and Plant Sterols
Dietary cholesterol comes mainly from animal products
○
The cholesterol produced in plant cell walls and oils is so minimal they are
considered cholesterol free
○
Phytosterols and stanols
Lower LDL levels by competing w/ cholesterol for absorption
§
Found in soybean oil, many fruits, vegetables, legumes, sesame
seeds, cereals, and other plant foods
§
Food manufactures are fortifying foods w/ them to help lower
cholesterol
§
○
-
Fat Substitutes Lower Fat in Foods
A research survey found that over 160 million Americans (79% of adult
population) chose lower-fat foods and beverages
Health concerns are major reason
§
○
Lower-fat foods contain fat substitutes
Designed to provide creamy properties of fat for fewer cals and
total fat grams
§
3 categories of fat substitutes
§
○
-
Carb-, Protein-, or Fat-Based Substitutes
Carb-based
Majority of fat substitutes
§
Use plant polysaccharides to help retain moisture and provide
fatlike texture
§
○
Protein-based
Created from protein in eggs and milk
§
Provide a creamy texture in mouth
§
○
Fat-based
Modified fats that provide the physical attributes of fat for fewer
cals than regular fat or interfere w/ absorption of fat
§
○
Overconsumption of cals from regular, low-fat, or fat-free products can
lead to weight gain
○
-
What is Heart Disease and What Factors Increase Risk?
Cardiovascular disease (CVD): encompasses disorders of cardiovascular
system, including heart
○
#1 killer of adults in US
○
Begins w/ atherosclerosis: arteries leading to the brain can cause a stroke
The progression:
Injury to lining of arteries promotes inflammation□
LDLs and other lipid substances accumulate at the injured site
and become oxidized by reacting w/ free radicals and metal
ions
□
Macrophages are attracted to the oxidized LDLs and then
form plaques
□
§
Primary risk factor is elevated blood lipids
§
Starting at 20, have a blood lipid profile analysis every 5 years
§
Measure cholesterol-to-HDL ratio
§
Have a risk score calculated
§
Consume less saturated and trans fats and moderate cholesterol
intake
Diets high in saturated fats raise LDLs in the blood□
High-cholesterol diet does not affect LDLs □
Type of saturated fat may have a greater impact on LDL levels
in the blood
Myristic and palmitic acids raise LDLs
®
Stearic acid doesn't raise LDLs
®
It is difficult to isolate foods by saturated fatty acid
type, recommended lowering overall saturated fatty
acid intake
®
□
Trans fats raise LDLs and blood triglycerides, and lower HDLs□
§
○
-
Eat More Fish and Plant Foods
Eat at least 2, 3.5 oz servings of fatty fish rich in omega-3 fatty acids
(alpha-linoleic acid)/ week
Baked, broiled, or poached
§
Limit consumption of EPA and DHA to 3 or less grams/ day
Increased risk for excessive bleeding□
May raise both blood glucose and LDL levels□
Intakes >3g occur only w/ supplementation□
Omega-3 fatty acid supplements should be taken w/ medical
supervision
□
§
Children and pregnant women should consume no more than 12 oz
of fatty fish/ week
§
Consume more plant foods
Canola oil, soy, flaxseeds, and walnuts are rich in ALA□
Choose plant foods rich in soluble fiber□
Consume at least 2 grams of plant sterols a day
Shown to lower LDL levels by 10%
®
Food rich in plant sterols include soybean oil, many
fruits, vegetables, legumes, nuts, and other plant foods
as well as margarine made w/ plant sterols
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Consume Antioxidants and Phytochemicals
Antioxidants and phytochemicals neutralize free radicals, stimulate
immune system to repair tissue damage, and reduce heart disease risk
Vitamin E, vitamin C, and beta-carotene
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Garlic may help lower cholesterol
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Flavonoids may help LDLs from oxidizing
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Nuts reduce LDL levels
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Get Plenty of Exercise, Manage Your Weight, and Quit Smoking
Exercise raises HDLs (good cholesterol), lowers LDLs, and reduces high
blood pressure and insulin resistance
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Aim for 30 minutes or more moderate exercise a day
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Quit smoking
Smoking damages walls of arteries and accelerates atherosclerosis
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Smokers are 3x more likely to have a heart attack than nonsmokers
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A Word about Protective Effects of Red Wine and Alcohol
Alcohol, in moderate amounts, can reduce the risk of heart disease,
mainly in middle-aged adults
Increases HDL levels
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Decreases blood clotting
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Moderate amounts are defined as no more than:
1 serving of alc/ day for females
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2 servings of alc/ day for males
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NUTR 2015 Chpt. 5: Lipids
Wednesday, February 7, 2018 2:00 PM
Document Summary
Lipids refer to a category of compounds that include: Contain c, o, and h (same structure as carbs except ) Hydrophobic, which means they don"t dissolve in water. Play a role in transporting fat-soluble nutrients in the blood. Chain of c and h atoms w/ a carboxyl group at the alpha end and a methyl group at the omega end. Fat has more cals (9) then carbs or proteins (4) b/c of higher ratio of. 4 types of fatty acids which vary by. Most common type in foods and take longer to digest than short or medium-chain fatty acids. Determined by whether carbons are held together by a. Determined by whether carbons are held together by a single or double bond. All carbons on fatty acid bound to hydrogen. Some carbons on fatty acid form a double bond. /w each other instead of binding to hydrogen. Double bonds are less stable than single bonds.
