Transcript Chapter 3

Fats
Functions of Fats in the Body
• Protect vital organs
• Digestion-fat in food is digested and absorbed
into adipose, or fatty, tissue
• Energy provider and reserve- helps the body
maintain a constant temperature
• Production and regulation of steroid
hormones
• Maintaining nerve impulse transmissionmyelin sheath
• Major component of cell membranes
• Transport the fat-soluble vitamins A, D, E, and K
Functions of Fats in Foods
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Energy-9 kcal/gram
Essential nutrients
Flavor and satisfaction
Fat substitutes are not absorbed and therefore
do not provide energy or essential nutrients but
may provide flavor and satisfaction
• Engineered fats
–Simpless
–Olestra
–Carrageenan
–Guar gum
Classes of Fats
• Lipids
• Glycerides
• Triglycerides
• Fatty acids
–Saturated
–Monounsaturated
–Polyunsaturated
• Lipoproteins
Lipids
• Organic substance made from
carbon, oxygen, and hydrogen
• Hydrophobic-do not dissolve in
water
• General term for a group of
compounds:
-Oils, fats, waxes, and
cholesterol
Triglycerides
• Basic unit of fat and are composed of three
("tri-") fatty acids individually bonded to three
carbons of glycerol
• Comes from the diet (meats and plant oils) and
our liver
• Found in the blood stream-blood fats
• Lipids are primarily stored as triglycerides in
adipocytes
• Elevated levels linked to Coronary Artery
Disease
Fatty Acids
• Saturated Fatty Acid:
–Filled or “saturated” with hydrogen
• Unsaturated Fatty Acid:
–Not completely filled with hydrogen
atoms; less heavy and dense:
• Monounsaturated:
–One unfilled spot
• Polyunsaturated:
–Two or more unfilled spots
Saturated Fatty Acids
• State of being filled; fat is harder
and solid. It’s structure is filled with
all the hydrogen atoms it can hold.
Saturated Fats
• Examples of saturated fats:
– Butterfat, coconut oil, palm oil, palm kernel
oil, animal fat (bacon, lard, egg yolk, dairy fat,
fatty meat)
Foods High in Monounsaturated
Fatty Acids
• Olive oil
• Canola oil
• Peanut oil
• Sesame oil
• Grapeseed oil
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Avocados
Hazelnuts
Almonds
Cashews
Sesame seeds
Pumpkin seeds
Macadamia nuts
Foods High in Polyunsaturated
Fatty Acids
• Safflower oil
• Salmon
• Mackerel
• Sunflower oil
• Herring
• Corn oil
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Trout
• Soybean oil
• Walnuts
• Cottonseed oil
• Sunflower seeds
• Most foods contain a combination of
saturated, monounsaturated and
polyunsaturated fats:
• Corn Oil-59% polyunsaturated and 24%
monounsaturated fatty acids
• Olive Oil-74% monounsaturated and 8%
polyunsaturated fatty acids
• Peanut Oil- 46% monounsaturated and
32% polyunsaturated fatty acids
• Butter-62% saturated fatty acids
• Coconut Oil-86% saturated fatty acids
Essential Fatty Acids
• Polyunsaturated fatty acids
–Linoleic (omega-6)
–Alpha-linolenic (omega-3)
• These fats MUST come from the foods we
eat. We cannot produce these as we can
the other types of fatty acids (saturated,
monounsaturated and cholesterol)
• 10% of a daily dietary intake needs to
come from essential fatty acids
Essential Fatty Acids
• Functions:
– Reduces inflammation
– May prevent risk factors associated with chronic
diseases such as heart disease, cancer, and
arthritis
– Aids in brain memory, performance, and behavioral
function
– Infants who do not get enough omega-3 fatty acids
from their mothers during pregnancy are at risk for
developing vision and nerve problems
– Symptoms of omega-3 fatty acid deficiency may
include fatigue, poor memory, dry skin, heart
problems, mood swings or depression, and poor
circulation
Linoleic (omega-6) Food Sources
• Safflower oil (richest natural
source)
• Sunflower oil
• Soybean oil
• Cottonseed oil
• Evening primrose oil
• Borage oil
• Meat, poultry, and eggs
Alpha-linolenic (omega-3)
Food Sources
• Flaxseed oil (highest linolenic content of any food),
flaxseeds, and flaxseed meal
• Soybean oil, canola oil, and wheat germ oil
• Hempseed oil and hempseeds
• Walnuts, pumpkin seeds, brazil nuts, and sesame
seeds
• Vegetables: grape leaves, kale, spinach, mustard
greens, turnip greens, arugula, brussel sprouts,
asparagus, cabbage, artichokes, broccoli, squash,
sweet peppers, avocados, okra, peas
• Salmon, herring, mackerel, sardines, anchovies,
albacore tuna, and caviar
Lipoproteins
• Combinations of triglycerides, cholesterol, and fat
soluble vitamins, and proteins
• Transport lipids and cholesterol in the blood
• They vary in density according to the fat load they
carry
– Low Density Lipoproteins (LDL’s)
• Carry cholesterol from the liver to cells of the
body
– High Density Lipoproteins (HDL’s)
• Collect cholesterol from the body's tissues, and
bring it back to the liver
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Cholesterol
Not a fat
A fat related compound
Soft waxy substance found in the bloodstream
Liver makes about 2 grams per day
No cholesterol in plant foods
Functions:
– Production of testosterone and estrogen
– Synthesis of Vitamin D
– Formation of Bile-aids in fat digestion
• Food sources:
– Dairy, meat, liver, kidneys, and eggs
• Limit intake to less than 300 mg daily
Healthy Cooking
Oils
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Olive oil
Canola oil
Flax seed oil
Peanut oil
Safflower oil
Sunflower oil
Corn oil
Bad Cooking Oils
• Vegetable
shortening
• Hard margarine
• Butter
• Palm oil
• Palm kernel oil
• Coconut oil
Hydrogenation
• Process of forcing hydrogen atoms into the holes of
unsaturated fatty acids
• Turns liquid fat (oil) into solid fats-longer shelf life and
creamier
• Destroys essential fatty acids
• This process creates a new fat called trans fatty acidsbody cannot use this fat and is deposited into arterial
walls
• Heart disease risk
• Trans fatty acids are found in margarine, shortening,
commercial baked foods like cookies, crackers, muffins,
and cereals
• Trans fat is similar to saturated fat because it tends to
increase LDL cholesterol levels, but dissimilar because it
also lowers HDL cholesterol levels as well
Digestion of Fats
• The primary digestion action occurring in the mouth is
mechanical. Foods are broken up into smaller
particles through chewing and moistened for passage
into the stomach
• Little, if any, chemical fat digestion takes place in the
stomach
• Small Intestine
– Fat digestion occurs here
– Enzymes from the pancreas
– Bile from the gallbladder
• Fat emulsifier: breaks fat into smaller particles
allowing enzymes to penetrate it
– Absorption
Dietary Fat Requirements
• 20-35 percent of your daily calories
• Less than 10% from saturated fat
• Linoleic acid (omega-6):
– 17 g/day for men
– 12 g/day for women
• Linolenic acid (omega-3):
– 1.6 g/day for men
– 1.1 g/day for women
• Dietary cholesterol be limited to 300 mg/day
• Trans Fat as low as possible
• Fat contains 9 calories per gram
Assignment
• Refer to page 43
• Answer questions Critical Questions 1, 3,
and 4