Ch 5 - The Lipids: Fats, Oils, Phospholipids, and Sterols

Intro

• cut down on saturated fats in your diet and replace them with oils to lower

  your risk of cardiovascular disease (CVD)

• No doubt you are expecting to hear that fats have the potential to harm your

  health, but lipids are also valuable. In fact, lipids are absolutely necessary, and

  dietary patterns recommended for health are by no means “no-fat” diets. Luckily, at

  least traces of fats and oils are present in almost all foods, so you needn’t make an effort to eat any extra.

Introducing the Lipids

• The lipids in foods and in the human body, though many in number and diverse in function, generally fall into 3 classes.

• About 95 percent are triglycerides. The other

  major classes of the lipids are the phospholipids (of which lecithin is one) and the sterols (cholesterol is the best known of these).

How Are Fats Useful to the Body?

• When people speak of fat, they are usually talking about triglycerides

• 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-orfamine existence: stored during times of plenty, fat helps keep them alive during times of famine.

  • 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.

• Efficiency of Fat Stores

  • You may be wondering why the carbohydrate glucose

    is not the body’s major form of stored energy. Glucose is stored in the form of glycogen. Because glycogen holds a great deal of water,

    it is quite bulky and heavy, and the body cannot store enough to provide energy for

    very long. Fats, however, 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 of a person whose weight falls in the healthy range contains more than enough energy to fuel an entire marathon run or to battle prolonged illness.

• Cushions, Climate, Cell Membranes, and Signaling

  • Pads of fat surrounding 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.

    Lipids also assist in transmitting cellular signaling

    messages that help control cell functions.

• Transport and Raw Material

  • Lipids move around the body in association with other 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.

Lipids provide and store energy, cushion vital organs, insulate against cold temperatures, form cell membranes, participate in cell signaling, transport fatsoluble substances, and serve as raw materials.

How Are Fats Useful in Food?

• They provide concentrated energy and needed

  substances to the body, and they are pleasing to the palate.

• Concentrated Calorie Source

  • Energy-dense fats are uniquely valuable in many

    situations. A hunter or hiker must consume a large amount of food energy to travel

    long distances or to survive in intensely cold weather. An athlete must meet often enormous

    energy needs to avoid weight loss that could impair performance. For such a person fat-rich foods most efficiently provide the

    needed energy in the smallest package. But for a person who is not expending much

    energy in physical work, those same high-fat foods may deliver many unneeded calories in only a few bites.

• Fat-Soluble Nutrients and Their Absorption

  • 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.

• Sensory Qualities

  • People naturally like high-fat foods. Fat carries with it many

    dissolved compounds that give foods enticing aromas and flavors, such as the aroma

    of frying bacon or French fries. In fact, when a sick person refuses food, dietitians

    offer foods flavored with some fat to spark the appetite and tempt that person to eat

    again. Fat also lends crispness to fried foods and tenderness to foods such as meats

    and baked goods. Around the world, as fats become less expensive and more available

    in a given food supply, people increasingly choose fatty foods.

• A Role in Satiety

  • 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.

Lipids provide abundant food energy in small packages, enhance aromas and flavors of foods, and contribute to satiety.

A Close Look at Lipids

• Each class of lipids—triglycerides, phospholipids, and sterols—possesses unique characteristics. The term fat refers to triglycerides, the major form of

  lipid found in food and in the body.

Triglycerides: Fatty Acids and Glycerol

• Very few fatty acids are found free in the body or in foods; most are incorporated into

  large, complex compounds: triglycerides. The name almost explains itself: three fatty

  acids (tri) are attached to a molecule of glycerol to form a triglyceride molecule. Tissues all over the body can easily assemble triglycerides or disassemble them

  as needed. Triglycerides make up most of the lipid present both in the body and in food.

• Fatty acids can differ from one another in two ways: in chain length and in degree

  of saturation. Triglycerides usually include mixtures of various fatty

  acids. Depending on which fatty acids are incorporated into a triglyceride, the resulting

  fat will be softer or harder at room temperature. Triglycerides containing mostly

  shorter-chain fatty acids or more unsaturated ones are softer and melt more readily at lower temperatures.

• Each species of animal (including people) makes its own characteristic kinds of triglycerides,

  a function governed by genetics. Fats in the diet, though, can affect the types of triglycerides made because dietary fatty acids are often

  incorporated into triglycerides in the body. For example,

  many animals raised for food can be fed diets containing

  specific triglycerides to give the meat or milk products the

  types of fats that consumers demand.

The body combines three fatty acids with one glycerol to make a triglyceride, its storage form of fat.

Fatty acids in food influence the composition of fats in the body.

Lipids in the Body

• From the moment they enter the body, lipids affect the body’s functioning and condition.

  They also demand special handling because fat separates from water and body

  fluids consist largely of water.

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.

• Fat in the Stomach

  • After being chewed and swallowed, food travels to the stomach.

    Once there, droplets of fat separate from the watery stomach contents 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

  • As the stomach contents empty into the small intestine,

    the digestive system faces a problem: how to thoroughly mix fats, which have separated

    into a layer, with its own watery fluids. The solution is an emulsifier: bile. Bile, made by

    the liver, is stored in the gallbladder and expelled through a duct that leads to the small

    intestine when it is needed for fat digestion. Bile contains compounds made from cholesterol

    that work as emulsifiers; one end of each molecule attracts and holds fat, while the other end is attracted to and held by water.

  • Bile emulsifies and suspends fat droplets within the watery fluids 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.

• Fat Absorption

  • Once split and emulsified, the fats face another barrier: 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. Beyond fat digestion,

    bile compounds play other diverse and intriguing roles, such as facilitating energy

    metabolism, signaling the brain and liver, and controlling bacterial growth in the colon.

  • The digestive tract absorbs triglycerides from a meal with remarkable efficiency:

    up to 98% 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.

In the stomach, fats separate from other food components.

In the small intestine, bile emulsifies the fats, enzymes digest them, and the intestinal cells absorb them.

How Does Fat Travel Around the Body?

• 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. Larger lipids, however, present

  a problem for the body. As mentioned earlier, fat floats in water. Without some mechanism

  to keep them dispersed, large lipid globules would separate out of the watery blood as

  it circulates around the body, disrupting the blood’s normal functions. The solution to this

  problem lies in an ingenious use of proteins: many fats travel from place to place in the watery

  blood as passengers in lipoproteins, assembled packages of lipid and protein molecules.

• Larger digested lipids, monoglycerides and long-chain fatty acids, must form lipoproteins

  before they can be released into the lymph in vessels that lead to the bloodstream. Inside the intestinal cells, these lipids re-form into triglycerides and cluster together

  with proteins and phospholipids to form chylomicrons that can safely carry lipids

  from place to place in the watery blood. Chylomicrons form one type of lipoprotein and are part of the body’s efficient lipid transport system.

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.

Storing and Using the Body’s Fat

• 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.

• The Body’s Fat Stores

  • Many triglycerides eaten in foods are transported by 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. (It also draws on its stored glycogen.)

  • With sufficient food energy, the body can convert excess carbohydrate to fat, but

    this conversion is not energy-efficient. Before excess glucose can be stored as fat, it

    must first be broken into tiny fragments by enzymes and then reassembled into fatty

    acids, steps that require energy to perform. (The body also possesses enzymes to convert

    excess protein to fat or to glucose, but these processes are even less

    efficient.) Storing fat itself is most efficient; fat requires the fewest chemical steps before storage. This does not mean that excess calories from carbohydrate- and protein-rich foods do not contribute to energy stores in the body, however—far from it. Excess calorie intakes reliably lead to weight gain.

• What Happens When the Tissues Need Energy?

  • Fat cells respond to the call for energy by dismantling stored fat molecules (triglycerides)

    and releasing fatty acids into the blood. Upon receiving these fatty

    acids, the energy-hungry cells break them down further into small fragments.

    Finally, each fat fragment is combined with a fragment derived from

    glucose, and the energy-releasing process continues, liberating energy, carbon

    dioxide, and water. The way to use more of the energy stored as body

    fat, then, is to create a greater demand for it in the tissues by reducing the intake of food energy, by increasing the body’s expenditure of energy, or both.

• Carbohydrate in Fat Breakdown

  • When fat is broken down to provide cellular

    energy, carbohydrate helps the process run most efficiently.

    Without carbohydrate, products of incomplete

    fat breakdown (ketone bodies) build up in the tissues and

    blood, and they spill out into the urine.

  • For weight-loss dieters who want to use their body fat for energy, knowing these

    details of energy metabolism is less important than remembering what research and

    common sense tell us: successful weight loss depends on taking in less energy than the

    body needs. The distribution of calories among energy nutrients doesn’t matter much in this regard. For the body’s health, however, the proportions of certain lipids in the diet matter greatly.

The body draws on its stored fat for energy.

Carbohydrate is necessary for complete breakdown of fat.

Dietary Fat, Cholesterol, and Health

• 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.

• People who center their diets on foods rich in saturated fatty acids and trans-fatty acids often have blood lipid profiles that indicate higher risks of developing

  CVD. 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.

• Reducing saturated fats is important, but what replaces them in the diet matters,

  too. When added sugars and refined carbohydrates take the place of saturated

  or trans fats, little benefit to health is observed. The greatest benefits can be expected

  from adopting a dietary pattern that includes protein-rich nuts, seafood, and soy foods;

  fiber–rich legumes, barley, and oatmeal; and a variety of fruits, vegetables, and other whole foods, with little saturated fat, refined grain, or added sugars.

• If you are a woman, take note: these observations apply to you. Heart disease kills

  more female adults in the United States than any other cause, and the old myth that heart disease is a “man’s disease” should be forever put to rest.

Recommendations for Lipid Intakes

• some fat is essential to good health. 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, linoleic acid and linolenic acid.

• A Healthy Range of Fat Intakes

  • Defining an upper limit—the exact gram amount

    of fat, saturated fat, or trans fat that begins to harm people’s health—is difficult, so no

    Tolerable Upper Intake Level for the lipids is set. Instead, the DRI committee suggests an

    intake range of 20%-35% of daily energy from total fat, less than 10% of daily

    energy intake from saturated fat, and as little trans fat as possible. In practical terms, for a

    2,000-calorie diet, 20 to 35 percent represents 400 to 700 calories from total fat (roughly

    45 to 75 grams, or about 9 to 15 teaspoons).

• U.S. Fat Intakes

  • According to surveys, the average U.S. diet provides about 35 percent

    of total energy from fat, with saturated fat contributing 12 percent of the total. Sandwiches (burgers, fried chicken sandwiches, lunch meat subs, and

    others) are the top providers of saturated fat, but sweets (brownies, candies, cookies, ice

    cream, snack cakes and bars), dairy, meats, mixed dishes (macaroni and cheese, fried rice,

    spaghetti and meatballs), and pizza all contribute substantially.

• Traditional Mediterranean Fat Intakes

  • In the mid-20th century, people eating

    the traditional diets of the Mediterranean Sea regions were observed to achieve a

    rare feat: they consumed a relatively large amount of dietary fat (about 40 percent of

    calories) while having low rates of cardiovascular diseases. 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 Dietary Pattern for meeting nutrient needs and lowering disease risks.

  • The fats of healthy Mediterranean-style diets derive mostly from avocados, extra

    virgin olive oil, fish, olives, nuts, and seeds. These foods are rich in unsaturated fatty

    acids and phytochemicals, and when they replace the saturated fats of butter, stick margarine,

    coconut and palm oil, or meats, improvements heart disease risks and its markers, such as blood clotting and inflammation, often follow.

  • Eating the Mediterranean way involves more than just

    adding olives to your taco salad or drizzling olive oil like a

    magic potion on a cheesy sausage pizza. The right way is to

    replace sources of saturated fat with foods rich in unsaturated

    oils to keep calories constant and avoid unneeded

    weight gain that could worsen disease risks.

• Too Little Lipid

  • A very few people manage to eat too little fat to support health.

    Among them are people with eating disorders who eat too little of all foods and

    misguided athletes hoping to improve performance. When fat intake falls short of

    the 20 percent minimum, energy, vitamins, and essential fatty acids may also be lacking,

    and the eater’s health may suffer.

  • lipids and heart health—they form the

    foundation of lipid intake recommendations. The lipoproteins take center stage because they play important roles in the health of the heart.

A small amount of raw oil is recommended each day.

Energy from fat should provide 20 to 35 percent of the total energy in the diet.

The high-fat foods of a Mediterranean dietary pattern present mostly unsaturated fats.

Lipoproteins and Heart Disease Risk

• Recall that monoglycerides and long-chain fatty acids from digested food fat depend on

  chylomicrons, a type of lipoprotein, to transport them around the body. Chylomicrons

  and other lipoproteins are clusters of protein and phospholipids that act as emulsifiers—

  they attract both water and fat to enable their large lipid passengers to travel dispersed

  in the watery body fluids. The tissues of the body can extract whatever fat they need

  from chylomicrons passing by in the bloodstream. The remnants are then picked up by the liver, which dismantles them and reuses their parts.

• Major Lipoproteins: Chylomicrons, VLDL, LDL, HDL The body makes 4 main types of lipoproteins, distinguished by their size and density. Each type contains different kinds and amounts of lipids and proteins: the more lipids, the less dense; the more protein, the more dense. In addition to chylomicrons, the lipoprotein with the least density, the body makes three other types of lipoproteins to carry its fats:

  • Very-low-density lipoproteins (VLDL), which transport triglycerides and other lipids made in the liver to the body cells for their use.

  • Low-density lipoproteins (LDL), 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.

  • High-density lipoproteins (HDL), which pick up cholesterol from body cells and carry it to the liver for disposal.

• The LDL and HDL Difference

  • The separate functions and effects of LDL and

    HDL are worth a moment’s attention because they carry important implications for the health of the heart and blood vessels:

    • 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. 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.

• The Importance of Cholesterol Testing The importance of blood cholesterol

  concentrations to heart health cannot be overstated. The blood lipid profile tells

  much about a person’s blood cholesterol and the lipoproteins

  that carry it. High blood LDL cholesterol and low

  blood HDL cholesterol account for 2 major risk factors for CVD.

The chief lipoproteins are chylomicrons, VLDL, LDL, and HDL.

High blood LDL and low blood HDL are major heart disease risk factors.

What Does Food Cholesterol Have to Do with Blood Cholesterol?

• “Not as much as most people think.” Most saturated food fats and

  trans fats raise harmful blood cholesterol, but food cholesterol is not well-established as a

  factor for raising blood cholesterol values in most people. When told that dietary cholesterol

  doesn’t matter as much as saturated or trans fats, people may then jump to the

  wrong conclusion—that blood cholesterol doesn’t matter. It does matter. High blood LDL

  cholesterol is a major indicator of CVD risk. The 2 main food lipids associated with

  raising it are saturated fat and trans fat when intakes exceed recommendations. Genetic

  inheritance modifies everyone’s ability to handle dietary cholesterol, however, so people

  who tend to develop high blood cholesterol should follow the advice of a physician.

• The Dietary Guidelines committee did not set a guideline for dietary cholesterol. Here’s

  why: People who consume a healthy diet that holds saturated fat to less than 10 percent

  of calories naturally take in less cholesterol because the same foods, such as fatty meats and cheeses, often provide both.

Saturated fat and trans fat intakes raise blood cholesterol.

Dietary cholesterol has little effect on blood cholesterol in most people.

Recommendations Applied

• In a welcome trend, fewer people in the United States have high blood cholesterol than

  in past decades. Even so, a large number—almost 40 million adults—still test too high

  for LDL cholesterol. To repeat, dietary saturated fat and trans fat can trigger a rise in

  LDL in the blood. Conversely, 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.

• Lowering LDL Cholesterol

  • A step toward improving

    blood lipids is to identify sources of saturated fat in

    the diet and reduce their intakes. Figure 5–13 shows that,

    when food is trimmed of fat, it also loses saturated fat and

    calories. A pork chop trimmed of its border of fat drops

    almost 70 percent of its saturated fat and 220 calories. A plain baked potato has no

    saturated fat and contains about 40 percent of the calories of one with butter and

    sour cream. Choosing fat-free milk over whole milk provides large savings of saturated fat and calories.

  • Nutritionists know this: the best diet for health not only replaces saturated fats with

    unsaturated oils but also is adequate, balanced, calorie-controlled, varied, and based

    mostly on nutrient-dense whole foods. The overall dietary pattern is important, too.

• Raising HDL

  • As for blood HDL cholesterol, most dietary measures are ineffective

    at raising HDL concentration. Regular physical activity raises it effectively and

    reduces heart disease risks. Physically active

    people also reap many other benefits.

To lower blood LDL cholesterol, follow a healthy dietary 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.

Fat in the Diet

• A way to find lipid values of many foods is to access an online nutrient

  database, such as USDA’s “What’s in the Foods You Eat” search tool.

Get to Know the Fats in Foods

• Fats, naturally occurring or added, are widely distributed among foods. Learning their sources can help you choose wisely among them.

• Essential Fats

  • Everyone needs the essential fatty acids and vitamin E provided by

    such foods as fish, nuts, and vegetable oils. Infants receive them indirectly via breast

    milk, but all others must choose the foods that provide them. Luckily, the amount of fat

    needed to provide these nutrients is small—just a few teaspoons of raw oil a day and two

    servings of seafood a week are sufficient. Most people consume more than this minimum

    amount. The goal is to choose unsaturated fats in liquid oils instead of saturated fats as often as possible.

• Visible vs. Invisible Fats

  • The fat of some foods, such as the rim of fat on a steak,

    is visible (and therefore identifiable and removable). Other 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 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 saturated fat in the U.S. diet.

• Replace, Don’t Add

  • Keep in mind that, whether solid or liquid, essential or nonessential,

    all fats bring the same abundant calories to the diet and excesses contribute to body fat stores. Each of the following provides about 5 grams of fat, 45 calories, and negligible protein and carbohydrate:

    • 1 teaspoon oil or shortening

    • 1 1⁄2 teaspoons mayonnaise, butter, or margarine

    • 1 tablespoon regular salad dressing, cream cheese, or heavy cream

    • 1 1⁄2 tablespoons sour cream

  • Remember to replace and not add. No benefits can be expected when oil is added to an already fat-rich diet.

Fats in Protein Foods

• The marbling of meats and the fat ground into lunchmeat, chicken products, and hamburger

  conceal a hefty portion of the saturated fat that people consume. All meats contain

  about equal amounts of protein, but their fat, saturated fat, and calorie amounts vary significantly. Nutrition Facts

  panels list the fat contents of many packaged meats.

  The USDA Dietary Patterns suggest that

  most adults limit their intakes of protein foods to about 5 to 7 ounces a day. For comparison,

  the smallest fast-food hamburger weighs about 3 ounces. Steaks served in restaurants

  often run 8, 12, or 16 ounces, more than a whole day’s meat allowance. You

  may have to weigh a serving or two of meat to see how much you are eating.

• Meat: Mostly Protein or Fat?

  • People recognize meat as a protein-rich food, but a

    close look at some nutrient data reveals a surprising fact. A fast-food hamburger made with a 4-ounce beef patty contains 23 grams of protein and 23 grams of fat, more than 8

    of them saturated fat. Because protein offers 4 calories per gram and fat offers 9, the meat

    of the sandwich provides 92 calories from protein but 207 calories from fat. Hot dogs,

    fried chicken sandwiches, and fried fish sandwiches also provide hundreds of mostly

    invisible calories of fat. Because so much meat fat is hidden from view, meat eaters can

    easily and unknowingly consume a great many grams of saturated fat from this source.

• Tips for Limiting Fats from Meats

  • When choosing beef or pork, look for lean cuts

    named loin or round from which the fat can be trimmed, and eat small portions. Chicken

    and turkey flesh are naturally lean, but commercial processing and frying add fats,

    especially to “patties,” “nuggets,” “fingers,” and wings. Watch out for ground turkey

    or chicken products. The skin is often ground in to add pleasing moistness, but the food

    ends up with more fat than the amount found in many cuts of lean beef. Some

    people (even famous chefs) misinterpret—reasoning that, if poultry

    or pork fat is less saturated than beef fat, it must be harmless to the heart. Nutrition

    authorities emphatically state, however, that all sources of saturated fat pose a risk and

    that even the skin of poultry should be removed before eating the food.

Meats account for a large proportion of the hidden saturated fat in many people’s diets.

Dairy Products

• Dairy products go by many names that reflect their varying fat contents. A cup of homogenized whole milk contains the protein and carbohydrate of

  fat-free milk, but in addition, it contains about 80 extra calories from butterfat, a mostly saturated fat. A cup of reduced-fat (2 percent fat) milk falls between whole and fat-free,

  with 45 calories of fat. The fat of whole milk occupies only a teaspoon or two of the volume but nearly doubles the calories in the milk.

• Milk and yogurt appear together in the Dairy Products group, but cream and butter

  do not. Milk and yogurt are rich in calcium and protein, but cream and butter are not.

  Cream and butter are high in saturated fat, as are whipped cream, sour cream, and

  cream cheese, and they are properly grouped together with other fats. Other cheeses,

  grouped with milk products, vary in their fat contents and are major contributors of

  saturated fat in the U.S. diet.

Dairy products bear names that identify their fat contents.

Grains

• Grain foods in their natural state are very low in fat, but fats of all kinds may be added

  during manufacturing, processing, or cooking. In fact, grain-based

  desserts, such as cookies, cakes, and pastries, which are often prepared with butter,

  margarine, or shortening, are among the top contributors of saturated fat in the U.S. diet. Other grain foods with high fat contents include

  biscuits, cornbread, granola and some other ready-to-eat cereals, croissants, doughnuts,

  fried rice, pasta with creamy or oily sauces, fried tortillas (crisp taco shells), snack

  and party crackers, muffins, pancakes, and homemade waffles. Packaged breakfast

  bars often resemble vitamin-fortified candy bars in their fat and sugar contents.

Fats in grain foods are often well hidden.

Fats added to grain foods contribute significant saturated fat to the diet.

Concepts/Terms

• Lipid

  • a family of organic (carbon-containing) compounds soluble in organic solvents but not in water. Lipids 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 and also found in animal-derived foods.

• Triglycerides

  • one of the three main classes of dietary lipids and the chief form of fat in foods and in the human body. A triglyceride is made up of three units of fatty acids and one unit of glycerol (fatty acids and glycerol are defined later).

• Cardiovascular Disease 

  • disease of the heart and blood vessels. Disease of the arteries of the heart is called coronary heart disease (CHD).

• Satiety

  • the feeling of fullness or satisfaction that people experience after meals.

• Solid Fats

  • EX: fatty meats and butter

• Saturated Fats

  • triglycerides in which most of the fatty acids are saturated.

• Trans Fats

  • fats that contain any number of unusual fatty acids—trans-fatty acids—formed during processing.

• Extra Virgin Olive Oil

  • minimally processed olive oil produced by mechanical means, such as pressing (not chemical extraction), to preserve phytochemicals, green color, and flavor from the original olives. The highest grade of olive oil.

• Inflammation

• HDL/LDL Cholesterol

  • high-density lipoproteins (HDL): lipoproteins that return cholesterol from the tissues to the liver for dismantling and disposal; contain a large proportion of protein; which pick up cholesterol from body cells and carry it to the liver for disposal. 😇

  • low-density lipoproteins (LDL): lipoproteins that transport lipids from the liver to other tissues such as muscle and fat; contain a large proportion of cholesterol; 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. 👺