chapter 5 nutrition- lipids

lipids key point

Lipids provide and store energy, cushion vital organs, insulate against cold temperatures, form cell membranes, transport fat-soluble substances, and serve as raw materials

where does the body store fat

Many triglycerides eaten in foods are transported by the chylomicrons to the fat depots—the subcutaneous fat layer under the skin, the internal fat pads of the abdomen, the breasts, and others—where they are stored by the body's fat cells for later use. When a person's body starts to run out of available fuel from food, it begins to retrieve this stored fat to use for energy

Body cells cannot make these two polyunsaturated fatty acids from scratch, nor can the cells convert one to the other.

The human body needs fatty acids, and it can use carbohydrate, fat, or protein to synthesize nearly all of them. Two are well-known exceptions: linoleic acid and linolenic acid.

are special transport vehicles for lipids in blood and lymph.

lipoproteins

chylomicrons-safely carry lipids from place to place in the watery blood.

lipoproteins formed when lipids from a meal cluster with carrier proteins in the cells of the intestinal lining. Chylomicrons transport food fats through the watery body fluids to the liver and other tissues.

What role does bile play in the digestion of fats?

Bile acts as an emulsifier so that fat-digesting enzymes can break down fats.

Saturated fats have a _______ potential for spoiling when exposed to oxygen or heated and unsaturated fats have a ________ potential for spoiling when exposed to oxygen or heated due to their chemical structure.

low; high

lipoproteins transport of fat

many fats travel from place to place in the watery blood as passengers in lipoproteins, assembled packages of lipid and protein molecules.

deffiencies of essential fatty acids

Deficiencies of the essential fatty acids are harmful but virtually unknown in the United States and Canada. -diet deficient in the essential polyunsaturated fatty acids produces symptoms such as skin abnormalities and poor wound healing. In infants, growth is retarded, and vision is impaired.

How Are Fats Digested and Absorbed?

Digestion- Stomach •Small intestine- Bile •Gallbladder •Absorption: Fatty acids split from glycerol- Fatty acids, phospholipids, and monoglycerides •Bile shuttles lipids across mucus layer •Up to 98 percent of fats consumed are absorbed• The more fat taken in at a meal, the slower the digestive system action

exceptions

-olive oil is a monounsaturated fat that remains liquid and turns cloudy in cold temperatures -solid fat of homogenized milk. Highly saturated milk fat normally collects and floats as a layer of cream (butterfat) on top of the watery milk fluids. Once skimmed from the milk and churned into butter, the solid fat quickly hardens in the refrigerator. During homogenization, heated milk and cream are forced under high pressure through tiny nozzle openings to finely divide and disperse the fat droplets evenly throughout the milk. Thus, fluid milk can be a source of solid fat that remains liquid at cold temperatures.

Lipid Intake Recommendations for Healthy People

1.Total fat Dietary Reference Intakes•An acceptable range of fat intake is estimated at 20 to 35 percent of total calories 2. Saturated fat American Heart Association•For adults who would benefit from lowering blood L D L cholesterol•Reduce percentage of calories from saturated fat to between 5 and 6 percent Dietary Reference Intakes- Keep saturated fat intake low, less than 10 percent of calories, within the context of an adequate diet Dietary Guidelines for Americans-•Consume less than 10 percent of calories per day from saturated fats 3. Trans fat American Heart Association•For adults who would benefit from lowering blood L D L cholesterol •Reduce percentage of calories from trans fat Dietary Guidelines for Americans-A healthy eating pattern limits trans fats 4. Polyunsaturated fatty acids Dietary Reference Intakes- Linoleic acid (at 5 to 10 percent of total calories)•17 grams/day for young men•12 grams/day for young women •Linolenic acid (at 0.6 to 1.2 percent of total calories)•1.6 grams/day for men •1.1 grams/day for women Dietary Guidelines for Americans-A healthy eating pattern includes oils 5.Cholesterol Dietary Reference Intakes•Minimize cholesterol intake within the context of a healthy diet

How Are Fats Digested and Absorbed?

A bite of food in the mouth first encounters the enzymes of saliva. An enzyme produced by a gland at the base of the tongue plays a major role in digesting milk fat in infants but is of little importance to lipid digestion in adults.

unsaturated fatty acid

A fatty acid carbon chain that possesses one or more points of unsaturation is an unsaturated fatty acid -A fatty acid carbon chain that possesses one or more points of unsaturation is an unsaturated fatty acid

phospholipids

A phospholipid, like a triglyceride, consists of a molecule of glycerol with fatty acids attached, but it contains two, rather than three, fatty acids. In place of the third is a molecule containing phosphorus, which makes the phospholipid soluble in water, while its fatty acids make it soluble in fat. This versatility permits any phospholipid to play a role in keeping fats dispersed in water—it can serve as an emulsifier.

Fat in the Stomach

After being chewed and swallowed, the food travels to the stomach, where droplets of fat separate from the watery components and tend to float as a layer on top. Even the stomach's powerful churning cannot completely disperse the fat, so little fat digestion takes place in the stomach.

Fat in the Small Intestine

Bile emulsifies and suspends fat droplets within the watery fluids (see Figure 5-8) until the fat-digesting enzymes contributed by the pancreas can split them into smaller molecules for absorption. These fat-splitting enzymes act on triglycerides to split fatty acids from their glycerol backbones. Free fatty acids, phospholipids, and monoglycerides all cling together in balls surrounded by bile emulsifiers. -To review: first, the digestive system mixes fats with bile-containing digestive juices to emulsify the fats. Then fat-digesting enzymes break down the fats into absorbable pieces. The pieces then assemble themselves into balls that remain emulsified by bile. People sometimes wonder how a person without a gallbladder can digest food. The gallbladder is just a storage organ. Without it, the liver still produces bile but delivers it to the small intestine instead of into the gallbladder.

Body's response to exercise

Blood lipids shift toward higher H D L cholesterol •Muscles of the heart and arteries strengthen and circulation improves •Larger volume of blood is pumped with each heartbeat, reducing the heart's workload •Body grows leaner, reducing the overall risk of cardiovascular disease •Blood glucose regulation is improved, reducing the risk of diabetes

LDL HDL difference

Both LDL and HDL carry lipids in the blood, but LDL are larger, lighter, and richer in cholesterol; HDL are smaller, denser, and packaged with more protein. LDL deliver cholesterol to the tissues; HDL scavenge excess cholesterol and other lipids from the tissues, transport them via the bloodstream, and deposit them in the liver. When LDL cholesterol is too high, it contributes to lipid buildup in tissues, particularly in the linings of the arteries, that can trigger inflammation and lead to heart disease; HDL cholesterol opposes these effects, and when HDL in the blood drops below the recommended level, heart disease risks rise in response. Both LDL and HDL carry cholesterol, but high blood LDL warns of an increased risk of heart attack, and so does low blood HDL (Chapter 11 has details). Thus, some people refer to LDL as "bad" cholesterol and HDL as "good" cholesterol—yet they carry the same kind of cholesterol. The key difference to health between LDL and HDL lies in the proportions of lipids they contain and the tasks they perform, not in the type of cholesterol they carry.

Cancer•

Cancer is the second leading cause of death in the United States. •Diets high in processed meats and/or red meats and obesity have been linked with a higher risk of colon cancer .•Weight gain during adulthood and obesity is linked with a higher risk of breast cancer after menopause •Being overweight or obese is clearly linked to cancer of uterus, esophagus, and kidney.

Dietary Fat and Health

Excess weight Cancer High Blood Pressure Heart disease and atherosclerosis-Number one killer for US men and women.-Many Americans have high blood cholesterol and high blood pressure.-Too much circulating cholesterol builds up in the walls of the arteries—especially the heart's arteries—which leads to plaque accumulation. Heart attack-myocardial infarction- occurs when the flow of blood to a section of the heart muscle suddenly becomes blocked. Stroke-occurs when the blood supply to part of the brain is cut off. Monitor blood lipid levels If deprived of blood for more than a few minutes, parts of the heart and brain can die.

satiety and fat; Slows down food movement sensory: Aromas (meat marbling differs flavors)•Solvents for flavors (cream & butter carry flavors)•Tenderness, lubricity, texture

Fat also contributes to satiety, the satisfaction of feeling full after a meal. The fat of swallowed food triggers a series of physiological events that helps to suppress the desire to eat. Still, people can easily overeat on fat-rich foods before the sensation stops them because the delicious taste of fat stimulates eating, and each bite of a fat-rich food delivers many calories. Over time, a chronically high-fat diet may weaken the satiety responses to fat, at least in rats

fat; fuel stores

Fat provides most of the energy needed to perform the body's muscular work. Fat is also the body's chief storage form for the energy from food eaten in excess of need. The storage of fat is a valuable survival mechanism for people who live a feast-or-famine existence: stored during times of plenty, fat helps keep them alive during times of famine.

Select the list of foods that supply mostly unsaturated oils.

Fish, nuts, olives

temperature of fatty acids; butter= saturated (hard), oil=unsaturated (soft/liquid)

Generally, the more unsaturated the fatty acids, the more liquid the fat will be at room temperature. Conversely, the more saturated the fatty acids, the more solid the fat will be at room temperature. **-The butter and oil are both at room temperature, but the saturated fats of the butter keep it solid—it has a higher melting point. Thus, looking at three fats—beef tallow (a type of beef fat), chicken fat, and safflower oil—beef tallow is the most saturated and the hardest; chicken fat is less saturated and somewhat soft; and safflower oil, which is the most unsaturated, is a liquid at room temperature.

transports of fats

Glycerol and short-chain fatty acids travel in the bloodstream unassisted. Other lipids need special transport vehicles—the lipoproteins—to carry them in watery body fluids.

glycerol transport of fat

Glycerol and shorter-chain fatty acids pass directly through the cells of the intestinal lining into the bloodstream, where they travel unassisted to the liver.

# cause of deaths in US associated with saturated and trans fats

High intakes of saturated and trans fats are associated with serious diseases, and particularly with heart and artery disease (cardiovascular disease, or CVD), the number-one cause of death among adults in the United States *****Heart disease kills more women in the United States than any other cause -When they replace these foods with those rich in polyunsaturated or monounsaturated fat, their blood lipids often shift toward a profile associated with good health.

Which statement accurately reflects the influence hydrogenation has on oils?

Hydrogenation causes oils to lose their unsaturated character.

fat cells; store fat

Most body cells can store only limited fat, but some cells are specialized for fat storage. These fat cells seem able to expand almost indefinitely—the more fat they store, the larger they grow. An obese person's fat cells may be many times the size of a thin person's. Far from being a collection of inert sacks of fat, adipose (fat) tissue secretes a huge variety of hormones and other compounds that help regulate appetite and influence other body functions in ways critical to health.

fatty acids/ fish oil and vegetable oil, animal fats

Most vegetable and fish oils are rich in polyunsaturated fatty acids. Some vegetable oils are also rich in monounsaturated fatty acids. Animal fats are generally the most saturated Coconut oil, for example, comes from a plant, but its fatty acids—even those of the heavily advertised "virgin" types—are more saturated than those of cream. Palm oil, a vegetable oil used in food processing, is also highly saturated. Likewise, shortening, stick margarine, and commercially fried or baked products may claim to be or use "all vegetable fat," but much of their fat may be saturated

transport and raw material of lipids

Once a lipid arrives at its destination, it may serve as raw material for making a number of needed products, among them vitamin D, which helps build and maintain the bones; bile, which assists in digestion; and lipid hormones, which regulate tissue functions.

fats cushion, climate to the body

Pads of fat surrounding the vital internal organs serve as shock absorbers. Thanks to these fat pads, you can play sports or ride a motorcycle for many hours with no serious internal injuries. A fat blanket under the skin also insulates the body and slows heat loss in cold temperatures, thus assisting with internal climate control. Lipids also play critical roles in all of the body's cells as part of their surrounding envelopes, the cell membranes.

Functions of the Essential Fatty Acids Essential fatty acids: examples of essential fatty acid= linoleic acid and linolenic acid.

Provide raw material from which eicosanoids (biologically active lipids) are made. Serve as structural and functional parts of cell membranes. Contribute lipids to the brain and nerves. Promote normal growth and vision. Maintain health of the skin, thus protecting against water loss. Help regulate genetic activities affecting metabolism. Participate in immune cell functions.

what does food cholestrol have to do with blood cholestrol

Saturated fat and trans fat intakes raise blood cholesterol. Dietary cholesterol has little effect on blood cholesterol in most people. •Most saturated and trans fats in foods raise harmful blood cholesterol •Food cholesterol has little effect on blood cholesterol •High blood L D L cholesterol is a major indicator of C V D risk •Food lipids associated with raising L D L cholesterol•Saturated fat and trans fat in excess amounts

saturation fatty acid-filled to capacity

Saturation refers to whether or not a fatty acid chain is holding all of the hydrogen atoms it can hold. If every available bond from the carbons is holding a hydrogen, a fatty acid carrying the maximum possible number of hydrogen atoms (having no points of unsaturation). A saturated fat is a triglyceride with three saturated fatty acids.

fat soluble nutrients

Some essential nutrients are lipid in nature and therefore soluble in fat. They often occur in foods that contain fat, and some amount of fat in the diet is necessary for their absorption. These nutrients are the fat-soluble vitamins: A, D, E, and K. Other lipid nutrients are fatty acids themselves, including the essential fatty acids. Fat also aids in the absorption of some phytochemicals, plant constituents that may be of benefit to health.

sterols

Sterols such as cholesterol are large, complicated molecules consisting of interconnected rings of carbon atoms with side chains of carbon, hydrogen, and oxygen attached. Cholesterol serves as the raw material for making emulsifiers in bile, important to fat digestion. Cholesterol is also important in the structure of the cell membranes of every cell, making it necessary to the body's proper functioning. Like lecithin, cholesterol can be made by the body, so it is not an essential nutrient. Other sterols include vitamin D, which is made from cholesterol, and the familiar steroid hormones, including the sex hormones.

recommendations for lipid intake 20-35% of total calories

The Dietary Guidelines for Americans recommend that a portion of each day's total fat intake come from a few teaspoons of raw oil, such as found in nuts, avocados, olives, or vegetable oils. A little peanut butter on toast or mayonnaise in tuna salad, for example, can easily meet this need. In addition, the DRI committee sets specific recommended intakes for the essential fatty acids

fitness for heart health

The blood, arteries, heart, and other body tissues respond to exercise in these ways: Blood lipids shift toward higher HDL cholesterol. The muscles of the heart and arteries strengthen and circulation improves, easing delivery of blood to the lungs and tissues. A larger volume of blood is pumped with each heartbeat, reducing the heart's workload. The body grows leaner, reducing the overall risk of cardiovascular disease. Blood glucose regulation is improved, reducing the risk of diabetes

importance of stored fat

The body draws on its stored fat for energy. Carbohydrate is necessary for the complete breakdown of fat.

Storing and Using the Body's Fat- rainy day

The conservative body wastes no energy. It methodically stores fat molecules not immediately required for energy. Stored fat serves as a sort of "rainy day" fund to fuel the body's activities at times when food is unavailable, when illness impairs the appetite, or when energy expenditures increase.

Mediterranean diet; low rates of cardiovascular diseases

The fats of healthy Mediterranean-style diets derive mostly from avocados, extra virgin olive oil, olives, nuts, and seeds. These foods are rich in unsaturated fatty acids and phytochemicals, and when they replace the solid fats of butter, stick margarine, coconut and palm oil, or meats, improvements in markers of heart disease risks, such as blood clotting and inflammation, often follow. -Their diets also provided abundant nutrients from vegetables, legumes, nuts and seeds, fruit, whole grains, fish, other seafood, and some cheeses and yogurt, but little red meat, few added sugars, and no ultra-processed foods. Today, the Dietary Guidelines for Americans recommend this healthy Mediterranean-style eating pattern for meeting nutrient needs and lowering disease risks.

Monounstaurated fatty acid

a fatty acid containing one point of unsaturation.

three types of fatty acids Saturated fat: Atriglyceride in which the maximum number of hydrogen atoms are attached to every carbon atom—thus, the fat is "saturated" with hydrogen atoms .•Monounsaturated fat: A triglyceride in which most of the fatty acids are monounsaturated—one fatty acid is missing a pair of hydrogen atoms in the middle .•Polyunsaturated fat: A triglyceride in which most of the fatty acids are polyunsaturated—several hydrogen atom pairs are missing.

The more carbon atoms in a fatty acid, the longer it is. The more hydrogen atoms attached to those carbons, the more saturated the fatty acid is. -saturated, monounsaturated, polyunsaturated Saturation •Hydrogen atoms •Levels of saturation •Saturated •Unsaturated-Polyunsaturated•Monounsaturated

visible vs invisible fats

The solid fat of some foods, such as the rim of fat on a steak, is visible (and therefore identifiable and removable). Other solid fats, such as those in candy, cheeses, coconut, hamburger, homogenized milk, and lunchmeats, are invisible (and therefore easily missed or ignored) Equally hidden are the solid fats blended into biscuits, cakes, cookies, chip dips, ice cream, mixed dishes, pastries, sauces, and creamy soups and in fried foods and spreads. ********Invisible fats supply most of the solid fats in the U.S. diet.

plant sterols

These plant sterols resemble cholesterol in structure and can inhibit cholesterol absorption in the human digestive tract, lowering the cholesterol concentration in the blood. Plant sterols occur naturally in nuts, seeds, legumes, whole grains, vegetables, and fruit and are added to margarine that can then bear a "heart-healthy" claim on the label.

polyunsaturated fatty acid,

With two or more points of unsaturation, often abbreviated PUFA

point of unsaturation

a site in a molecule where the bonding is such that additional hydrogen atoms can easily be attached.

glycerol

a small, water-soluble carbohydrate derivative, plus three fatty acids equals a triglyceride. -an organic compound, three carbons long, of interest here because it serves as the backbone for triglycerides.

What role does fat play in a healthy diet?

a. Fat helps the body use vitamins A, D, E, and K. b. Fat contributes to satiety after a meal. c. Fat helps with the absorption of some phytochemicals

triglycerides- usually when spoken about fat its this -Three fatty acids attached to glycerol molecule Fatty acid differences•Chain length•Degree of saturation •Each animal species makes its own characteristic kinds of triglycerides

an energy-rich compound made up of a single molecule of glycerol and three molecules of fatty acid -Triglycerides make up most of the lipid present both in the body and in food. -(most plentiful fat in the body). 90 % of body fat or adipose tissue Excess CHO in diet will increase TG level

lipids

are organic compounds soluble in organic solvents but not in water.

What are symptoms associated with a diet deficient in essential polyunsaturated fatty acids?

b. Skin abnormalities and poor wound healing

Which of the following forms of fat is most saturated?

beef tallow

_____ is/are important for the emulsification of fat in the small intestines, and ________ is/are important for the transport of fat in the blood.

bile; lipoproteins

transport triglycerides eaten in foods to the subcutaneous fat layer under the skin.

chlyomicrons

Which lipoprotein transports dietary fat to the cells in your body?

chylomicrons

what are the chief lipoproteins

chylomicrons, VLDL, LDL, and HDL.

Lipoproteins

clusters of lipids associated with protein, which serve as transport vehicles for lipids in blood and lymph. The major lipoproteins include chylomicrons, VLDL, LDL, and HDL.

Which grain-based food likely has the most saturated fat?

croissants

atherosclerosisa

disease of the arteries characterized by lipid deposits known as plaques along the inner walls of the arteries; a major cause of cardiovascular disease -Cholesterol forms the major part of the plaques that narrow the arteries, the underlying cause of heart attacks and strokes.

Which nutrient group supplies most of the energy needed to perform the body's muscular work?

fat

_________ are the leading single contributor of solid fats to the U.S. diet.

grained based deserts

the process of _______ creates trans-fatty acids

hydrogenation

A "point of unsaturation" in a fatty acid is a place where ________ are missing.

hydrogens

cholestrol

is important in the structure of the cell membranes of every cell, making it necessary to the body's proper functioning.

Linoleic acid -essential for skin The omega-6 family of polyunsaturated fatty acids includes linoleic acid and arachidonic acid.; Starting material for making eicosanoids

is the "parent" member of the omega-6 fatty acid family, so named for the chemical structure of these compounds. Given dietary linoleic acid, the body can produce other needed members of the omega-6 family. One of these is arachidonic acid, notable for its role as a starting material from which the body makes a number of biologically active lipids, known as eicosanoids. Somewhat like hormones, eicosanoids arise in tissues where they help regulate body functions and then are quickly destroyed. Omega-6 fatty acids are supplied abundantly in the U.S. diet by vegetable oils.

Regular physical activity

is the best way to raise blood HDL cholesterol.

Linolenic acid- needed to make hormones The omega-3 family includes linolenic acid, EPA, and DHA. Docosahexaenoic acid (D H A) and eicosapentaenoic acid (E P A) play critical roles in:•Regulating heart disease•Cancer prevention •Promoting healthy tissue functioning by amassing in cell membranes•Brain function and vision

is the parent member of the omega-3 fatty acid family. Given dietary linolenic acid, the body can make other members of the omega-3 series. Two family members of great interest to researchers are EPA and DHA. The body makes only limited amounts of EPA and even less DHA, but they are found abundantly in the oils of certain fish. U.S. intakes of these oils are limited. Seafood -Recommendation: 8 to 12 ounces each week -Variety of types (cold water fish > warm) -Need for sustainable sources• Fish oil supplements •Omega-3 enriched foods

Hydrogenation form trans fatty acids Altering fatty acids in food while processing •Makes fats resistant to oxidation and helps stay fresher longer •Unsaturated oils get rancid on oxidation •Hydrogenated oils•Have a high smoking point •Easy to handle and easy to spread Fried foods like french fries and doughnuts-Baked goods including pastries and cookies-Pie crusts and biscuits-Frozen pizza-Ready-made frosting-Microwave popcorn-Stick margarines and shortenings

of fats makes them resistant to oxidation, and helps them stay fresher longer. It changes their physical properties. -Vegetable oils become more saturated when they are hydrogenated. Hydrogenated vegetable oils are useful, but they lose the health benefits of unsaturated oils. **An alternative to hydrogenation for extending a product's shelf life is to add a chemical preservative that will compete for oxygen and thus protect the oil. The additives are antioxidants, and they work by reacting with oxygen before it can do damage. Examples are the additives BHA and BHT listed on snack food labels. Another alternative, already mentioned, is to keep the product refrigerated.

The degree of saturation determines

of the fatty acids in a fat determines the fat's softness or hardness.

what to eat omega 6, omega 3s. DHA and EPA

omega 6: Linoleic acid Nuts and seeds (cashews, walnuts, sunflower seeds, others) Poultry fat Vegetable oils (corn, cottonseed, safflower, sesame, soybean, sunflower); margarines made from these oils Omega-3 Linolenic acid Nuts and seeds (chia seeds, flaxseeds, walnuts, soybeans) Vegetable oils (canola, flaxseed, soybean, walnut, wheat germ; liquid or soft margarine made from canola or soybean oil) Vegetables (soybeans) EPA and DHA: Egg, enriched: 75-100 mg DHA/egg (flaxseed-enriched) 100-130 mg DHA/egg (fish oil-enriched) Human milk Fish and seafood: -fatty fish Top contributors: (500-1,800 mg/3.5 oz) Barramundi, Mediterranean seabass (bronzini), herring (Atlantic and Pacific), mackerel, oyster (Pacific wild), salmon (wild and farmed), sardines, shark, swordfish, tilefish, toothfish (includes Chilean seabass), lake trout (freshwater, wild, and farmed) Good contributors: (150-500 mg/3.5 oz) Black bass, catfish (wild and farmed), clam, crab (Alaskan king), croakers, flounder, haddock, hake, halibut, oyster (eastern and farmed), perch, scallop, shrimp (mixed varieties), sole Other contributors: (25-150 mg/3.5 oz) Cod (Atlantic and Pacific), grouper, lobster, mahi-mahi, monkfish, orange roughy, red snapper, skate, tilapia, triggerfish, tuna, wahoo

fat store efficiency

pack tightly together without water and can store much more energy in a small space. Gram for gram, fats provide more than twice the energy of carbohydrate or protein, making fat the most efficient storage form of energy. The body fat found on a normal-weight person contains more than enough energy to fuel an entire marathon run or to battle prolonged illness.

What type of language on meat packaging would a person want to avoid when they are trying to choose lean meat?

patties

Which class of lipid can serve as an emulsifier?

phospholipids

Where does most fat digestion occur?

small intestine

eat more of these

the greatest benefits can be expected from focusing the diet on protein-rich nuts, seafood, and soy foods; fiber-rich legumes, barley, and oatmeal; and a variety of fruit, vegetables, and other whole foods, with little solid fat, refined grain, or added sugars.

emulsification ex oil and vinegar/ mayonaisse

the process of mixing lipid with water by adding an emulsifier. -Some salad dressings separate to form two layers—vinegar on the bottom, oil on top, Other dressings, such as mayonnaise, are also made from vinegar and oil, but they never separate. The difference lies in a special ingredient of mayonnaise, the emulsifier lecithin of egg yolks. Lecithin, a phospholipid, blends the vinegar with the oil to form a stable emulsion: spreadable mayonnaise.

fat absorption

the watery layer of mucus that coats the absorptive lining of the digestive tract. Fats must traverse this layer to enter the cells of the digestive tract lining. The solution again depends on bile, this time in the balls of digested lipids. The bile shuttles the lipids across the watery mucus layer to the waiting absorptive surfaces on cells of the intestinal villi. The cells then extract the lipids. The bile may be absorbed and reused by the body, or it may flow back into the intestinal contents and exit with the feces -The digestive tract absorbs triglycerides from a meal with remarkable efficiency: up to 98 percent of fats consumed are absorbed. Very little fat is excreted by a healthy system. The process of fat digestion takes time, though, so the more fat taken in at a meal, the slower the digestive system action becomes.

three categories of lipids

triglycerides (95%), phospholipids, sterols -Lipids are organic compounds soluble in organic solvents but not in water -The problem with fats has more to do with the TYPE of fat you eat rather than the QUANTITY. •Most Americans need to replace saturated fat with monounsaturated and polyunsaturated fat to decrease heart disease risk.

recommendations to diet on cholestrol

trimming the saturated fat and trans fat from foods and replacing them with monounsaturated and polyunsaturated fats while keeping calories reasonable can lower LDL levels. *To lower LDL in the blood, follow a healthy eating pattern that replaces dietary saturated fat and trans fat with polyunsaturated and monounsaturated oils. *To raise HDL in the blood and lower heart disease risks, be physically active.

abundantly supplies omega-6 fatty acids in the U.S. diet.

vegetable oil

High-density lipoproteins (HDL), HDL Increased by Exercise and Diet high in poly, mono and omega fatty acids

which pick up cholesterol from body cells and carry it to the liver for disposal. smaller, denser, and packaged with more protein. HDL scavenge excess cholesterol and phospholipids from the tissues for disposal. -HDL - Healthy

Low-density lipoproteins (LDL), Increased by Excess weight Smoking High sat fat diet Couch potato Alcohol

which transport cholesterol and other lipids to the tissues for their use. LDL are what is left after VLDL have donated many of their triglycerides to body cells LDL - larger, lighter, and richer in cholesterol. Delivers cholesterol and triglycerides from the liver to the tissues.-LDL - Less healthy.

Very-low-density lipoproteins (VLDL),

which transport triglycerides and other lipids made in the liver to the body cells for their use.

Storing and Using the Body's Fat

•Body conserves fat molecules: •Fat depots- Subcutaneous fat layer •Excess carbohydrate •Call for energy: •Dismantle stored triglycerides- Release fatty acids into blood •Carbohydrate's role in fat breakdown

Foods High in Polyunsaturated Fat

•Corn oil •Soybean oil •Sunflower oil •Nuts and seeds •Fatty fish

Foods High in Saturated Fat- contribute to heart disease

•Mostly animals foods -Beef, pork (sausage, franks, bacon) -Grains-based desserts such as cookies (made with fat and eggs) -Whole milk and dairy products made with whole milk such as many cheeses and ice cream -Butter-French fries & other fried foods -Eggs, poultry skin -Also tropical oils: coconut, palm kernel, and palm oils

Foods High in Monounsaturated Fat

•Olive oil; Potential health benefits-Darker the better (extra virgin)- heart health •Canola oil- heart health •Peanut oil •Peanut butter •Avocado •Olives •Sesame oil and seeds