Chapter 5 Notes – The Lipids: Fats, Oils, Phospholipids, and Sterols
●Lipids
- A family of organic compounds soluble in organic solvents but not in water
- Include triglycerides (fats and oils), phospholipids, and sterols
●Cholesterol
-A member of the group of lipids known as sterols
- A soft waxy substance made in the body for a variety of purposes
- Also found in animal-derived foods
●Fats
-Lipids that are solid at room temperature
●Cardiovascular Disease (CVD)
- Disease of the heart and blood vessels
- Disease of the arteries of the heart is called coronary heart disease (CHD)
Introducing the Lipids
●Lipids in foods and in the human body fall into three classes
- Triglycerides
about 95% of all lipids in foods and the human body
- Phospholipids
for example, lecithin
- Sterols
for example, cholesterol
The Usefulness of Fats
Fats in the body
●Energy stores
-fats are the body’s chief form of stored energy
●Muscle fuel
-fats provide most of the energy to fuel muscular work
●Emergency reserve
-fats serve as an emergency fuel supply in times of illness and
diminished food
intake
●Padding
-fats protect the internal organs from shock through fat pads inside the body
●Insulation
-fats insulate against temperature extremes through a fat layer under the skin
●Cell membranes
-fats form the major material of cell membranes
●Raw Materials
-fats are converted to other compounds, such as hormones, bile, vitamin D, as needed
Fats in Food
●Nutrient
-fats provide essential fatty acids
●Energy
-fats provide a concentrated energy source in foods
●Transport
-fats carry fat-soluble vitamins A, D, E, and K along with some
assist in their absorption
●Raw materials
-fats provide raw material for making needed products
●Sensory appeal
-fats contribute to the taste and smell of foods
●Appetite
-fats stimulate the appetite
●Satiety
-fats contribute to feelings of fullness
●Texture
-fats help make foods tender
phytochemicals, and
Usefulness of Fats in the Body
●Fat
- Body’s chief storage form for the energy from food eaten in excess of need
-valuable survival mechanism for people who live in a feast-or-famine existence
-Provide most of the energy needed to perform much of the body’s work
-especially muscular work
●Most body cells can store only limited fat
- Some cells are specialized for fat storage
-these fat cells seem to expand indefinitely
-the more they store, the larger they grow
-Andipose (fat) tissue secretes hormones and produces enzymes that influence food
intake and affect the body’s use of nutrients
●Glucose, in the form of glycogen, is not the body’s major form of energy storage
-Glycogen stores a large amount of water
-therefore it is heavy and bulky
-thus, the body cannot store enough to provide energy for very long
●Fat is the body’s major storage form of energy
-Fats pack tightly together without water
-Relative to carbohydrate, much more fat can be stored in a small space
-Gram for gram, fats provide more than 2x the energy of carbohydrate
-making fat an efficient storage form of energy
●Body fat
-The amount on a normal-weight person is more than sufficient to provide energy for an
entire marathon or to battle disease should the person become ill and stop eating for a
while
●Other functions of fat
-Shock absorbers
-pads of fat surround vital internal organs
-Thermoregulation
-fat pads under the skin insulate the body from extremes of temperature
-Cell membranes
-lipids are a component of cell membranes
-Essential nutrients
-the fat-soluble vitamins (A,D,E, and K) are soluble in fat)
-found mainly in foods that contain fat
-absorbed more efficiently from these foods
-fat also aids in the absorption of some phytochemicals
-Essential fatty acids
-serve as raw materials from which the body makes certain required molecules
●The energy density of fats makes food rich in fat valuable in many situations
-For example, a hunter of hiker needs to consume a large amount of food energy
to travel long distances or to survive in intensely cold weather
-For a person who is not expending much energy in physical work, the
same high-fat foods may deliver many unneeded calories in only a few
bites
Usefulness of Fats in Foods
●People naturally like high-fat foods
-As fat becomes less expensive and more available in a given food supply, people seem
to choose diets providing greatly increased amounts of fat
-Fats carry many dissolved compounds that give foods enticing aroma and flavors
-Fat also lends tenderness to foods such as meats and baked goods
●Fats contribute to satiety
-the feeling of fullness or satisfaction that people experience after meals
-the fat of swallowed food triggers a series of physiological events that slow the emptying
of the stomach and promote satiety
-even before the sensation of fullness stops them people can easily overeat fat-rich
foods because of the delicious taste
Triglycerides: Fatty Acids and Glycerol
●Triglyceride = 3 fatty acids + glycerol
-fatty acids
-organic acids composed of carbon chains of various lengths
-each has an acid end and hydrogens attached to all of the carbon atoms of
the chain
-differ on the basis of length and degree of saturation
-glycerol
-an organic compound, three carbons long
-serves as the backbone for triglycerides
●Triglycerides usually include a mixture of fatty acids
-the nature of the fatty acids determines if the triglyceride is hard or soft
-mostly shorter-chained fatty acids or unsaturated ones are softer and melt more
readily at lower temperatures
●Fats in the diet can affect the types of triglycerides made
-dietary fats are often incorporated into triglycerides in the body
-for example, many animals raised for food can be fed diets containing softer or
harder triglycerides to give the animal softer or harder fat
-whichever consumers demand
Saturated versus Unsatured Fatty Acids
●Saturation refers to whether or not a fatty acid chain is holding all of the hydrogen
atoms it can hold
-Point of saturation
-site in a molecule where the bonding is such that addition hydrogen atoms can
easily be attached
●Saturated fatty acid
-every available bond from the carbons is holding a hydrogen
●Monounsaturated fatty acid
-contains one point of unsaturation
●Polyunsaturated fatty acid (PUFA)
-contains two or more points of unsaturation
●Degree of saturation
-affects the temperature at which fat melts
-in general, the more unsaturated the fatty acids, the more liquid the fat is at room
temperature
-in general, the more saturated the fatty acids, the firmer the fat is at room
temperature
-Trans fats
-contain unusual fatty acids that are formed during processing
-Animal fats are generally the most saturated
-There is a benefit to heart health when monounsaturated or polyunsaturated fats replace
saturated and trans fat in the diet
●Olive Oil
-Rich in monounsaturated fatty acids
-evidence from Mediterranean regions suggests that olive oil confers a degree of
protection against heart disease when used in place of other fats
-dark-colored olive oils also deliver valuable phytochemicals
●Canola oil
-rich in both monounsaturated and polyunsaturated fatty acids
-supports heart health when replacing saturated fats in the diet
Phospholipids and Sterols
●Phospholipids = 2 fatty acids + glycerol + a phosphorus-containing molecule
-fatty acid is soluble in fat
-phosphorus is soluble in water
●Phospholipids are emulsifiers
-a substance that mixes with both fat and water and permanently disperses the fat in the
water
-forming an emulsion
●Food processors blend fat with watery ingredients by way of emulsification
-the process of mixing lipid with water by adding an emulsifier
-in salad dressings vinegar and oil separate to form two layers; whereas mayonnaise, also
made of vinegar and oil, never forms two separate layers
-the difference is the presence of lecithin, an emulsifier, in mayonnaise
●Lecithin and other phospholipids play key roles in the structure of cell membranes
-Phospholipids are able to help fats travel back and forth across the lipid-containing
membranes of cells into the watery fluids on both sides
-Lecithin supplements have no special ability to promote health
-the body can make all that it needs
●Sterols
-Large, complicated molecules consisting of interconnected rings of carbon atoms with
side chains of carbon, hydrogen, and oxygen
●The sterol cholesterol serves as the precursor for making bile
-an emulsifier made in the liver and stored in the gallbladder
-does not digest fats
-emulsifies fats in such a way that enzymes in the watery fluids may contact it and
split the fatty acids from their glycerol for absorption
●Vitamin D and sex hormones are also sterols
●Cholesterols
-component of cell membranes
-can be made by the body
-not an essential nutrient
-forms the major parts of the plaques that narrow arteries in atherosclerosis
-the underlying cause of heart attacks and strokes
Lipids in the Body
●Lipids affect the body’s functioning and condition
Demand special handling because fat separates from water, and body fluids consist
largely of water
Digestion and Absorption of Fats
●Tongue
-An enzyme produced by the tongue plays a major role in digesting milk fat in infants
-little importance to digestion in adults
●Stomach
-Fat separates from the watery components and floats as a layer on the top
●Small Intestine
-Bile
-produced by the liver
-stored in the gallbladder
-secreted in the small intestine
-emulsifies fat
●No gallbladder?
-gallbladder is just a storage organ
-liver still produces bile
-delivers it continuously to the small intestine
-those who have had their gallbladder removed must initially reduce their fat intake
-they can no longer store bile and release it at mealtime so they can handle only a
little fat at a time
-Emulsified fat particles acted on by fat-digesting enzymes contributed by the pancreas
-fats are split into smaller particles for absorption
-triglycerides – split fatty acids from glycerol
-Free fatty acids, glycerol and monoglycerides cling together in balls surrounded by bile
-in order to be absorbed, fats must pass through the water layer of mucus that
coats the absorptive lining of the digestive tract
-bile shuttles the lipids across the mucus layer to the absorptive cells of the
intestinal villi
-the cells extract the lipids
-the bile may be absorbed and reused or exit with the feces
-the digestive tract absorbs triglycerides from a meal with up to 98% efficiency
-i.e. little fat is excreted by a healthy system
-the process of fat digestion takes time
-the more fat taken with a meal, the slower the digestive system becomes
●Shorter products of lipid digestion
-Glycerol and short-chain fatty acids pass directly through the cells of the intestinal lining
into the bloodstream
-Travel unassisted to the liver
●Larger products of lipid digestion
-without a mechanism to keep it dispersed, large lipid globules would separate out of the
watery blood and disrupt the blood’s normal function
-lipoproteins
-clusters of lipids associated with protein
-serve as transport vehicles for lipids in blood and lymph
-major classes include: chylomicrons, VLDLs, LDLs, and HDLs
-monoglycerides and long-chain fatty acids are formed into lipoproteins before being
released into the lymph that leads to the blood
-inside intestinal cells, they are reformed into triglycerides and clustered together with
proteins and phospholipids
-forming chylomicrons – a type of lipoprotein
How can I use my stored fat for energy?
●Chylomicrons transport triglycerides to the fat depots
-muscles
-breasts
-insulating fat layer under the skin
-etc.
●Fat is stored for later use
-when a person’s body starts to run out of available energy from food, it begins to
retrieve stored fat to use for energy
-fat cells dismantle stored fat molecules and release the components into the blood
-upon receiving these components, cells break them down into smaller fragments
each of which is combined with a fragment derived from glucose
-the energy-releasing process continues, liberating energy, carbon dioxide, and
water
●More of this fat can be used for energy by increasing demand for it
-this can be done by doing either/or
-decreasing intake of food energy
-increasing the body’s expenditure of energy
●Carbohydrate is required for the complete break down of fat into energy
-without carbohydrate the incomplete breakdown of fat produces ketones
-ketones build up in the blood and urine
●Excess carbohydrate can be stored as fat
-this conversion is not efficient
-glucose must be broken down into fragments which are then reassembled into
fatty acids
-steps that require energy
-fat requires fewer chemical steps before storage
●Weight-loss dieters
-successful weight loss depends on a low energy intake
-not the proportion of nutrients
Dietary Fat, Cholesterol, and Health
●High intakes of certain dietary fats are associated with serious disease
-diets high in saturated fats or trans fats are at increased risk of heart and artery disease
(CVD)
-heart disease is the number-one killer of adults in the U.S. and Canada
-High fat diets are associated with an increased risk of certain types of cancer as well as
the health risks associated with obesity
●table 5-2 Recommendations concerning intakes of fats for healthy people (p. 150)
Lipoproteins and Heart Disease Risk
●Major Lipoproteins: VLDL, LDL, HDL
-Very-low-density lipoproteins (BLDL)
-carry triglycerides and other lipids made in the liver to the body cells for their
use
-Low-density lipoproteins (LDL)
-transport cholesterol and other lipids to body tissues
-made from VLDL after they have donated many of their triglycerides to body
cells
-High-density lipoproteins (HDL)
-carry cholesterol from body cells to the liver for disposal
●The LDL and HDL difference
-LDL
-larger, lighter, and richer in cholesterol than HDL
-Deliver triglycerides and cholesterol from the liver to tissues
-HDL
-smaller, denser, and packaged in more protein than LDL
-scavenge excess cholesterol and phospholipids from tissues for disposal
-Elevated LDL concentrations in the blood are an indication of heart attack risk
-Elevated HDL concentrations in the blood are associated with a low heart attack risk
-The difference is attributable to the proportions of lipids they contain and the tasks they
perform
-the difference is not in the type of the cholesterol they carry
●The Importance of LDL and HDL Cholesterol
-Blood LDL and HDL cholesterol account for two major CVD risk factors
-high blood LDL concentration is a predictor of the likelihood of suffering a fatal
heart attack or stroke
-the higher the LDL, the earlier the episode is expected to occur
-high HDL cholesterol lowers disease risk
●Risk factors that cannot be changed
-increasing age
-being male
-family history of premature heart disease
●Risk factors that a person can often control
-High blood LDL; low blood HDL
-High blood pressure
-Diabetes
-Obesity
-Physical inactivity
-Cigarette smoking
-Atherogenic diet
What does Food Cholesterol Have to Do with Blood Cholesterol?
●Most saturated food fats and trans fats raise blood cholesterol more than food
cholesterol does
-high blood cholesterol is an indicator of risk for CVD
-main dietary factors associated with elevated blood cholesterol are high saturated
fat and trans fat intakes
●Heart disease-LDL link
-When high blood cholesterol signifies a risk of heart disease, it is because the LDL are
carrying cholesterol, made mostly from saturated fat in the diet, to body tissue
-When high blood cholesterol is in HDL, cholesterol is being carried away from body
tissues
●Genetics
-about 60% of people exhibit little increase in their blood cholesterol even with a high
dietary intake
-some people respond to high dietary cholesterol intake with greatly increased blood
cholesterol
-a few individuals have inherited a total inability to clear from their blood the cholesterol
they have eaten and absorbed
-those with a genetic tendency toward high blood cholesterol must strictly limit fats and
refrain from eating foods rich in cholesterol
-for most others, a limited amount of liver, eggs, and other cholesterol-containing food
poses no threat for incurring high blood cholesterol
-the body slows cholesterol synthesis when the diet provides greater amounts
-Moderation, not elimination, is the key for most people as far as cholesterol-containing
foods are concerned
Lowering LDL Cholesterol
●To lower high blood pressure
-reduce fat intake
-especially saturated and trans fats
-success is affected by genetics
-food trimmed of fat is also trimmed of much of its saturated fat and energy
●HDL Cholesterol
-Dietary measures are generally ineffective at significantly raising its concentration
-regular physical activity defends against heart disease partly because it effectively raises
HDL
●LDL is susceptible to damage by oxidation
-the interaction of a compound with oxygen
-in this case, a damaging effect by a chemically reactive form of oxygen
-evidence indicates that oxidation of the lipid part of LDL is injurious to the arteries of
the heart
●Dietary antioxidants may slow LDL oxidation
-vitamins C and E, selenium, antioxidant phytochemicals
Recommendations Applied
●Health authorities
-some recommend that all adults take steps to reduce their LDL cholesterol
-some recommend that only those medically identified as having an elevated risk for
heart disease need to take steps to lower their LDL cholesterol
●A good idea to choose a diet that
-provides 20%-35% of its calories from fat
-keeps saturated fat intake below 10% of caloric intake
-keeps trans fat intake below 1% of caloric intake
-substitute monounsaturated or polyunsaturated fat for saturated and trans fat
-note: instead of, NOT in addition too
-Fruits, vegetables, and whole grains
-supply abundant nutrients and antioxidants along with beneficial fiber
-Cholesterol intake
-proceed with caution
-eggs, shellfish, liver, and other cholesterol-containing foods are nutritious
-cholesterol cannot be omitted from the diet without omitting nutritious foods
-many high-cholesterol foods are also high in saturated fat
Think Fitness: Why Exercise the Body for the Health of the Heart?
●Response of blood, arteries, heart, and other body tissues to exercise
-blood HDL concentration increases
-shifting blood lipids in a healthy direction
-circulation improves
-easing delivery of blood to the heart
-a larger volume of blood is pumped with each heartbeat
-reducing the heart’s workload
-the body grows leaner
-reducing overall risk of cardiovascular disease
Essential Polunsaturated Fatty Acids
●Linoleic acid and linolenic acid
-the only fatty acids that cannot be synthesized by the body
-essential nutrients
-polyunsaturated fatty acids
-used by the body to make eicosanoids
-biologically active compounds that regulate body functions
●Eicosanoids regulate functions such as
-muscle relaxation and contraction
-blood vessel dilation and constriction
-blood clot formation
-blood lipids
-response to injury and infection
-fever
-inflammation
-pain
●DRI:
-Linoleic acid
-5%-10% of total calorie intake
-young men: 17g/day
-young women: 12 g/day
-Linoleic acid
-0.6%-1.2% of total calorie intake
-men: 1.6 g/day
-women: 1.1 g/day
Deficiencies of Essential Fatty Acids
●Deficiency of all polyunsaturated fatty acids leads to the appearance of:
-symptoms of reproductive failure
-skin abnormalities
-kidney disorders
-liver disorders
Omega-6 and Omega-3 Fatty Acid Families
●Linoleic acid
-an omega-6 fatty acid
-a polyunsaturated fatty acid with its endmost double bond 6 carbons from the end
of the chain
-can be used to produce other omega-6 fatty acids
-Arachidonic acid
-starting material from which a number of eicosanoids are made
●Linolenic acid
-an omega-3 fatty acid
-a polyunsaturated fatty acid with its endmost double bond carbons from the end
of the chain
-can be used to produce other omega-3 fatty acids
-EPA and DHA
-body makes limited amounts
-abundant in fish oils
●EPA and DHA
-a diet that includes two meals of fatty fish each week can reduce deaths and illness from
heart disease
-especially in people who have already suffered a heart attack
-Fish is more beneficial than fish oil supplements
●Omega-3 fatty acids
-support immunity
-inhibit the development of certain cancers
Recommendations for Omega-3 Fatty Acid Intake
●For healthy children and adults
-a normal balanced diet that includes grains, seeds, nut, leafy vegetables, oils, and fish
supplies all the needed forms of fatty acids in abundance and prevents deficiencies
-including fatty fish in a meal 2-3 times a week, for a total of about 12-14 ounces
of fish/week, can help achieve a healthy balance between omega-3 and omega-6
fatty acid intakes needed for health
●Foods high in omega-6 fatty acids should be consumed in moderation
-most vegetable oils and other fats
●Food preparation
-fish should be grilled, baked, or broiled
-conserves EPA and DHA versus fried or frozen fish
-frying adds saturated and trans fats
Food sources of Omega-6 and Omega-3 Fatty acids
●Omega-6
Linoleic acid – leafy vegetables, seeds, nuts, grains, vegetable oils (corn, cottonseed,
safflower, sesame, soybean, sunflower), poultry fat
●Omega-3
Linolenic acid – oils (canola, flaxseed, soybean, walnut, wheat germ, liquid or soft
margarine made from canola or soybean oil) nuts and seeds (butternuts, flaxseeds,
walnuts, soybeans) vegetables (soybeans
●EPA and DHA – Human milk, fatty coldwater fish (mackerel, salmon, bluefish, mullet,
sablefish, menhaden, anchovy, herring, lake trout, sardines, tuna)
Fish oil supplements
●Taking fish oil supplements is not recommended
-may raise LDL cholesterol
-high omega-3 polyunsaturated fatty acid intake may
-increase bleeding time
-interfere with wound healing
-suppress immune function
-lack other beneficial nutrients found in fish
-iodine
-selenium
-often made from fish skins and liver
-may have accumulated toxic concentrations of
-pesticides
-heavy metals, such as mercury
-other industrial contaminants
-Fish oil naturally contains high levels of two of the most potentially toxic vitamins
-A and D
-Are expensive
-Excessive amounts of either omega-3 or omega-6 fatty acids
-can interfere with normal functions that depend on a proper balance between the
two
The Effects of Processing on Unsaturated Fats
●Vegetable oils make up most of the added fat in the U.S. diet
-fast-food chains use them for frying
-food manufacturers add them to processed foods
-consumers tend to choose margarine over butter
●Vegetable oils tend to be less saturated than animal fats
What is “Hydrogenated Vegetable Oil”, and What’s it doing in my chocolate chip
cookies?
●Hydrogenation
-the process of adding hydrogen to unsaturaged fatty acids to make the fat more solid and
resistant to the chemical change of oxidation
●Points of saturation
-vulnerable to attack by oxygen
-when oxidized the oils become rancid
-cooking oils should be stored in tightly covered containers that exclude air
-if stored for long periods, they need refrigeration to retard oxidation
-prevents spoilage of unsaturated fats
-makes unsaturated fats harder and more stable when heated to high temperatures
-hydrogenated oil is suitable for purpose such as frying; it has a high smoking point
-the temperature at which fat gives off an acrid blue gas
●Hydrogenated oils
-easy to handle
-easy to spread
-store well
●Once fully hydrogenated, an oil loses both its unsaturated character and health benefits
-hydrogenation also affects some vitamins
-for example, vitamin K activity is decreased
●An alternative to hydrogenation
-Addition of a chemical preservative that will compete for oxygen
-thus, protecting the oil
-the additives are antioxidants
-work like vitamin E
-react with oxygen before it can do damage
-For example, BHA and BHT
-Keep refrigerated
What are Trans Fatty Acids and Are they Harmful?
●Trans fats
-unusual saturated fatty acids
-similar in shape to saturated fatty acid
-not made by the body
-naturally occur in tiny amounts mainly in dairy foods and beef
-affect the body’s health
●Consumption of trans fats
-raise LDL and lower HDL cholesterol
-produce inflammation
-thus, increasing the risk of heart disease
-DRI: as little as possible
●Diets high in total fats and especially in trans fats
-may be associated with cancer risk
-to date, there is no evidence that trans fats themselves play a specific role in promoting
or causing cancer
Fat in the Diet
●Fat delivers more calorie per bite than the other energy-yeilding nutrients
●Limiting energy intake may be important to maintaining good health
●Fat is necessary for health
-People who try to eliminate fat from their diet put their health at rise
-most adults need about 20% of their daily energy from fat
●Average U.S. diet
-1965: 45% of calories from fat
-Now: 35% of calories from fat
-Problem: despite the percentage of total calorie reduction the actual amount of fat
consumed has increased
-the number of grams of carbohydrate has increased even more
-net result: an increase in the number of calories consumed
●Lessons to be learned
-recognize the fats in food
-keep consumption of harmful saturated and trans fats to a minimum
-distinguish these fats from the more beneficial unsaturated fats
-control portion sizes
-particularly of fatty foods
●USDA Food Guide
-Oils always contain fat
-Solid fats group always contains fat
-meat, poultry, fish, legumes, eggs, and nuts group always contains fat
-milk, yogurt and cheese group sometimes contains fat
-grains group sometimes contains fat
-most unprocessed vegetables and fruits are fat-free; except
-avacados and olives
-rich in monounsaturated fats
-unprocessed grains contain little or no fat
●Visible fat
-example: fat trimmed from a steak
●Invisible Fat
-Examples:
-marbling of meat
-fat ground into lunch meats and hamburger
-fats blended into sauces of mixed dishes
-fats in avocado, biscuits, cheese, coconuts, other nuts, olives, and fried foods
-On the rise in U.S. diets
●Olestra
-An artificial fat: Olestra
-A sucrose polymer
-chemically, bears some resemblance to an ordinary fat
●Human enzymes of the digestive tract do not recognize the molecules of loestra
-cannot split its fatty acids from its sucrose
-passes through the digestive tract and exits intact
●Properties are identical to those of fats and oils when used in frying, cooking, and
baking
●Aside for a slight aftertaste, to many people it tastes like fat
●Safe in Most regards
●When consumed in large quantities can cause
-Digestive distress
-Nutrient losses
-Losses of phytochemicals
●May be capable of causing
-Diarrhea
-gas
-cramping
-an urgent need to defecate
●Oily olestra can creep through the feces and leak uncontrollably from the anus
-producing smelly, dark yellow stains on underwear
●A potent solvent for the fat-soluble vitamins and other fat-soluble substances in food
-absorption of these substances are reduced when a meal contains olestra
-olestra dissolves them and carries them out of the digestive tract
-to compensate, olestra is fortified with vitamins A, D, E, and K
●Causes the loss of health-promoting phytochemicals
-3 grams/day of olestra reduced absorption of lycopene by about 40%
●Pros of Olestra
-zero calories
-zero fat, saturated fat, and trans fat
-zero cholesterol
-withstands frying
-withstands baking
-tastes like fat
●Cons of Olestra
-vitamin losses
-phytochemical losses
-possible digestive upset
-possible anal leakage
-slight aftertaste
-expensive
-no long-term studies in children
Meat, Poultry, Fish, Legumes, Eggs, and Nuts
●Meats conceal a large amount of the fat people consume
-much of it is saturated fat
-organize meats into four categories based on their fat content (as the exchange lists do)
-very lean
-lean
-medium-fat
-high-fat
●USDA Food Guide
-suggests most adults limit intake to 5-6 oz. per day
-a very small amount by average consumption standards
-a small fast-food hamburger weighs about 3 oz
-a steak served in a restaurant often runs 8, 12, or 16 oz
-more than a whole day’s meat allowance
Milk, Yogurt and Cheese
●Some milk products contain fat
-Homogenizing whole milk
-milk processors blend in the cream
-which otherwise would float to the top and could be removed by skimming
●1 cup of whole milk
-versus fat-free milk
-contains the same amount of protein and carbohydrate as fat-free milk
-contains about 60 extra calories from fat
-versus reduced-fat (2 percent fat) milk
-45 calories from fat
-whole milk contains only 1-2 teaspoons of fat by volume
-which nearly doubles the calories in the milk
●Cheeses are the single greatest contributor of saturated fat in the diet
●Among plant food fats
-only the lipids of palm oil and coconut oil rank higher for saturation than the butterfat in
fatty dairy products
Grains
●In their natural state, grains are very low in fat
-fat, including saturated fat and trans fat, may be added during manufacturing,
processing, or cooking
-the fats in these foods can be difficult to detect
High-Fat Foods
●DRI recommendations for Fat
-To promote low rates of heart disease, diabetes, obesity, and cancer a diet should:
-get no more than 35% of its calories from fat
-be low in saturated and trans fats
-replace these fats with unsaturated fats
-control energy intake
●Olive Oil: The Potential connection
-The traditional Mediterranean diets are exemplary in their use of “good” fats
-especially olives and their oils
-when used in place of butter, meat fats, etc. olive oil may protect against heart
disease
●How olive oil may protect against heart disease
-Lowering total and LDL cholesterol and not lowering HDL cholesterol or raising
triglycerides
-Lowering LDL cholesterol’s vulnerability to oxidation
-Lowering blood-clotting factors
-Providing phytochemicals that act as antioxidants
-Lowering blood pressure
●The Mediterranean Diet: Beyond Olive Oil
-Olive oil does not reserve all the credit for the low rates of heart disease among those
consuming a traditional Mediterranean diet
-Each of the countries bordering the Mediterranean Sea has its own culture, tradition, and
dietary habits
-however, there are some common characteristics
●Common characteristics of traditional Mediterranean diets
-Crusty breads
-Whole grains
-Nuts
-Potatoes
-Pastas
-A variety of vegetables
-including wild greens
-A variety of legumes
-Feta and mozzarella cheese and yogurt
-Fruits
-especially grapes and figs
-some fish and other seafood
-poultry
-a few eggs
-a little meat
-along with olives and olive oil, principal sources of fat are nuts and fish
-rarely use butter
-rarely encounter saturated fats
●Traditional Mediterranean Diets are:
-low in saturated fat
-very low in trans fat
-rich in unsaturated fat
-rich in complex carbohydrates and fiber
-rich in nutrients and phytochemicals that support good health
●Major sources of saturated fat in the U.S. diet
-fatty meats
-over a third of the fat in most meats is saturated
-whole-milk products
-over half the fat in whole milk, and other high-fat diary products, is saturated
-coconut and palm oils
-mostly used in commercially prepared foods