Intro to Nutrition Chapter 6
Approximately 98% of the bile salts in bile are reabsorbed in the ileum, where they...
enter the bloodstream and travel to the liver. The liver incorporates the bile salts into new bile.
Hydrophobic
fearing; portion that avoids water substances.
Gallstones usually consist primarily of cholesterol. Gallstones can be small and...
grainy or as large as a dime and lumpy.
The American Heart Association has identified major risk factors for developing CVD. The more risk factors a person has, the...
greater his or her likelihood of CVD. A person cannot change a nonmodifiable risk factor, such as age and genetics.
Individuals with a family history of CVD should consider having their...
hs-CRP levels measured.
The hydrogen atoms of the double-bond carbons within the...
hydrocarbon chain are on opposite sides of the chain.
Cholesterol
is the most well-known sterol.
Steatorrhea
is the presence of lipid in the stool.
Diseases that affect the intestinal tract can interfere with digestion and cause...
poor absorption of fat, called fat malabsorption. Diarrhea, steatorrhea, and rapid weight loss are the most common signs of fat malabsorption.
Prostaglandins
produce a variety of important effects on the body; such as stimulating uterine contractions, regulating blood pressure, and mediating the immune systems inflammatory response.
After absorption, fatty acids, glycerol, monoglycerides, and phospholipid fragments are...
reassembled into triglycerides and phospholipids within the absorptive cells of the small intestine.
The majority of lipid absorption occurs in the small intestine, particularly in the duodenum and jejunum. Glycerol...
fatty acids, monoglycerides, cholesterol, and phospholipid fragments are the end products of lipid digestion
If the affected area is large, amputation of the...
gangrenous limb is often necessary to prevent life-threatening infection.
Lipid storage diseases are...
genetic conditions that cause lipid accumulation in cells, which damages tissues.
However, some dietary fat is essential for...
good health, and certain types of fats may actually decrease the risk of developing chromic disease and promote optimal health.
Furthermore, elevated blood pressure can cause...
hardened arteries to tear or burst, causing serious bleeding or sudden death, depending on the artery's size and location.
Triglyceride
has three fatty acids bonded to glycerol, a three carbon alcohol that is often referred to as the "backbone" of the triglyceride.
Clotting is an important function of blood, but having blood that clots too readily can increase the risk of heart attack and stroke. The role of omega-6 fats in preventing....
heart disease is controversial among medical experts
Hypertension is a major risk factor for developing atherosclerosis and heart disease. The heart of a person with....
hypertension must work harder to circulate blood through abnormally stiff arteries.
People with elevated CRP are more likely to develop CVD and...
hypertension than people who have lower levels of the protein. Thus, elevated CRP may be a biomarker for atherosclerosis, like homocysteine.
However, there are different types of LDL, and not all forms of the lipoprotein are unhealthy. LDL is...
needed to transport lipids to tissues, where the nutrients are used to make cell structures and vital compounds.
Most cases of heart disease and stroke result from atherosclerosis, a chronic process that...
negatively affects artery function.
Research published in 2016 found that replacing 5%...
of energy from saturated fat with an equal amount of energy from PUFA and MUFA fats was associated with a 27% reduction in mortality from CVD in U.S. adults.
For example, a young man has a total blood cholesterol level of 180 mg/dL. Of that amount, only 30 mg/dL are carried by high-density lipoprotein. This man's rato...
of total cholesterol to HDL cholesterol is 6:1 (180 mg/30 mg).
Alpha-linolenic acid is an...
omega-3 fatty acid
Each glycerol backbone can bond with up to....
three fatty acids. A glycerol molecule bonded to one, two, or three fatty acids called monoglyceride, diglyceride, respectively.
Eating low-fat foods is not the only way to meet this recommendation. By balancing intakes of low-fat and high-fat foods...
daily fat intake can average less than 35% of total energy intake.
In addition go chylomicrons, the body makes three major types of lipoproteins. Each type carries...
different proportions of protein, cholesterol, triglycerides, and phospholipids.
Bile contains bile salts, compounds that enhance...
digestion and absorption by emulsifying lipids in the watery environment of the small intestine.
The process of recycling bile from the intestinal tract is called...
enterohepatic circulation. Interfering with enterohepatic circulation can reduce blood cholesterol levels because the liver must use cholesterol to make new bile salts.
Cholesterol recommendations:
As little as possible while consuming a healthy diet.
Non modifiable Risk factors:
Family history of CVD (especially before 60 years of age), Increasing age, Male sex, Race/ethnic background.
Why did food manufacturers make products that contain PHOs?
Foods made with PHOs can be stored for loner periods than foods that contain cis fatty acids.
Plants contain substances, such as soluble fiber that interfere with cholesterol and bile absorption. Soluble fiber in the...
GI tract binds with bile in the jejunum and ileum, preventing the bile salts from being reabsorbed.
People who use soft or liquid spreads can lower their blood...
LDL cholesterol more than those who use butter.
People with a high ratio of total cholesterol to HDL cholesterol usually have too much...
LDL cholesterol n their blood and an increased risk of heart disease and stroke.
Saturated fat recommendations:
Less than 10% of total calories (22 grams saturated fat for a 2000 kcal diet)
Monounsaturated fatty acid (MUFA)
Only one double bond linking two carbon atoms
The body needs AA, EPA, and DHA to make....
a group of long-chain fatty acids that have hormonelike functions.
By having both hydrophilic and hydrophobic regions,....
a phospholipid can serve as an emulsifier.
Unlike triglycerides.....
a phospholipids are partically water soluble because the phosophorus-containing portion of the molecule is hydrophilic.
Emulsifier
a substance that keeps water-soluble and water-insoluble compound mixed together.
Cholesterol and the reassembled triglycerides are coated with....
a thin layer of protein, phospholipids, and cholesterol to form chylomicrons.
Sterols
are lipids that have a more chemically complex structure than a triglyceride or phospholipid.
Egg yolks, liver, wheat germ, peanut butter, and soybeans....
are rich sources of lecithin, the most abundant phospholipid in food.
Processed foods that include "fully hydrogenated" or "interesterified" oil...
are sources of interesterified fat.
Plant sterols and stanols (including sitostanol)
are structurally similar to cholesterol. These lipids occur naturally in small amounts in many grains, fruits, vegetables, nuts, seeds, and legumes.
Many people think cholesterol is unhealthy and foods that contain cholesterol should be....
avoided.
A phospholipid molecule also has a hydrophobic portion that...
avoids watery substances.
Another trait people cannot change is their family history. For example...
if your father had his first heart attack when he was 42 years old, you have a greater risk of developing heart disease prematurely (too soon) than someone whose father had his first heart attack at 75 years of age.
Choline
in lecithin, a water-soluble, vitamin-like acetylcholine.
Lipids
include triglycerides, phospholipids, and sterols, such as cholesterol.
Cardiovascular disease (CVD)
includes heart disease (coronary artery disease, or CAD), stroke, and diseases of the blood vessels.
Foam cells form plaque. Thus, oxidized LDL contributes to atherosclerosis. Several lifestyle behaviors, including cigarette smoking...
increase the oxidation of LDL. VLDL contains only about 15% of the cholesterol in the bloodstream, but this lipoprotein carries a lager share of triglycerides than cholesterol.
The condition however, is quite serious because it damages arterial walls and...
increases the risk of stroke, heart failure, and kidney disease.
The use of an artificial lipid,....
interesterified oil, to replace artificial trans fats in processed foods may also have undesirable health effects.
Oleic acid
is also an 18-carbon fatty acid, but it is a MUFA because it has one double-bond
Stearic acid
is an 18 carbon SFA
Linoleic acid
is an omega-6 fatty acid.
Phospholipid
is chemically similar to a triglyceride, except that one of the fatty acids is replaced by a chemical group that contains phosphorus, and, often, nitrogen.
Cholesterol also...
is essential to health as it is an integral component of every cell membrane in the body.
The protein content of a lipoprotein contributes to its density. A chylocmicron....
is the largest and least dense of the lipoproteins. Compared to other lipoproteins, chylomicrons carry much more fat and very little protein.
When a person eats a cheeseburger and french fries, an inactive...
lipase in his or her saliva mixes with the food.
Some people are unable to lower risk of CVD significantly by...
making dietary changes, exercising regularly, and losing excess body fat.
Following a diet that emphasizes unsaturated fats, rather than saturated or trans fats,...
may also lower the risk of premature death.
A stroke can...
happen when a clot blocks an artery in the brain and brain cells that are nourished by the vessel die. When an artery to a limb is blocked, the tissue in the extremity dies, causing gangrene to occur.
An unsaturated fatty acid...
has at least two neighboring carbons within the chain that are missing two hydrogen atoms, and a double bond holds the two particular carbons together.
A cis fatty acid
has the two carbon atoms that are connected by a double bond, each having a hydrogen chain.
Approximately 86 million Americans are living with one or more forms of CVD. In 2014....
heart disease and stroke together accounted for nearly half of all deaths.
Populations that consume diets rich in saturated fats (SFAs) generally have...
higher rates of CVD than populations that eat less saturated fat.
According to the American Heart Association, an estimated 80 million American adults have...
hypertension, which is typically a result of a poor diet, lack of physical activity, stress, and family history. Is a major risk factor for developing atherosclerosis and heart disease.
The reason appears to be that, in a healthy person, the liver synthesizes less cholesterol when dietary cholesterol intake is higher. On the other hand, eating large amounts of...
saturated fat increases the liver's cholesterol production
Although a woman's risk of developing CVD increases after menopause, her risk is...
still less than that of a man of the same age. Americans of African, Mexican, or Native American ancestry are more likely to have heart disease than those of other racial or ethnic backgrounds.
Emulsification keeps lipids dispersed in small particles, which increases their....
surface area and enables lipase to gain greater access to the individual lipid molecules.
Most research is needed to determine...
the longterm safety of consuming foods that contain interesterified oil
Eggs are a relatively economical and rich source of high-quality protein and many micronutrients. However, egg yolks are..
the most concentrated source of cholesterol in the typical American's diet.
Numerous studies conducted over the past 60 years indicate that consuming high amounts of certain lipids may increase....
the risk of developing serious health conditions, including obesity, certain cancers, and cardiovascular diseases (CVD), which includes heart disease and stroke.
Excess body fat, especially in the abdominal region, increases....
the risk of type 2 diabetes and hypertension. Physical inactivity also contributes to excess body fat.
People who have a higher risk of gallstones include women, those over age 40...
those with a family history of gallstones, those who are overweight or obese, and those who lose weight rapidly.
Diabetes and obesity are other modifiable risk factors for developing CVD. According to the American Diabetes Association, two in...
three people with diabetes also report having high blood pressure or taking prescription medications to control their blood pressure.
Certain cooking methods, however, can increase the tenderness of lean cuts of meat. Moist cooking methods, such as pot roasting or....
tightly covering the baking disk with foil, help tenderize the meats without adding fat.
It is healthier to have higher levels of HDL cholesterol, compared to normal ranges, than...
to have higher levels of LDL cholesterol, compared to normal ranges. Approximately one in three U.S. adults has high LDL cholesterol.
Pancreatic lipase digests triglycerides by removing two fatty acids from each triglyceride molecule. Some...
triglycerides are completely broken down into glycerol and fatty acid molecules
After cooking, avoid eating the visible fat that remains. For example...
trim away much of the fat from the meat, and do not use pan drippings to make sauces or gravies.
Tobacco use is another and modifiable risk factor for atherosclerosis. Compared to nonsmokers, smokers have...
two to four times the likelihood of developing heart disease and having a stroke.
Phospholipid deficiencies among adults are....
uncommon because these lipids occur in a variety of foods and healthy adults synthesize these compounds.
Having one or more risk factors increases a person's chances of developing the condition. It is important to...
understand that a risk factor is not the same as a cause of disease.
Excess body fat, especially around the midsection of the body, is associated with...
unhealthy blood LDL cholesterol and triglyceride levels.
Arterial plaque interferes with circulation because it narrows the artery and...
may even block its entire opening (lumen). Furthermore, plaque roughens the normally smooth arterial endothelial surface, which slows blood flow to the area supplied by the artery. This makes clots more likely to form.
Most triglycerides contain....
mixtures of unsaturated and saturated fatty acids. In a particular food, such as olives of cheese, the unsaturated and saturated fats occur in different proportions but only one type of fatty acids (SFA, MUFA, or PUFA) often predominates.
Some LDLs are smaller and denser than others. People with high levels of small, dense LDLs are...
more likely to develop atherosclerosis than people with low levels of these LDLs.
Most cells can use the fatty acids and glycerol for energy or production of body fat. After being stripped of...
most of its fat, VLDL becomes low-density lipoprotein. About 45% of the volume of a low-density lipoprotein is cholesterol.
Cells use linoleic acid to make certain eicosanoids that increase inflammation and blood clotting. Some inflammation is....
necessary because it attracts immune system cells to disease-causing microorganisms.
Trans fat in processed food (artificial trans fat) resulted from....
partial hydrogenation.
Nearly one in three adult Americans has hypertension Hypertension is often referred to as a "silent disease" because...
people with the condition frequently feel healthy and do not have obvious symptoms that indicate trouble with their circulatory system.
In the body....
phospholipids are major structural components of cell membranes.
Phospholipids are naturally found in foods derived from....
plants and animals.
According to the Dietary Guidelines adults should emphasize foods that are rich sources of...
polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.
Although atherosclerosis begins during adolescence and young adulthood, it usually does not..
produce symptoms of CVD until decades later.
The trans configuration at the double bond enables the hydrocarbon chain to be....
relatively straight, which is similar to a SFA molecule's structure. Fats that contain a high proportion of trans fatty acids are more solid at room temperature than those with a high proportion of cis fatty acids.
Most naturally occurring unsaturated fatty acids are...
cis fatty acids.
Prostaglandins, thromboxanes, adn leukotrienes are...
classes of eicosanoids.
Chemists identify a fatty acid by....
(1) its number of carbon atoms (2) the type of bond between carbon atoms in the hydrocarbon chain. These two characteristics influence how fatty acids can affect health.
Alpha-linolenic acid recommendations:
0.6-1.2% of total calories (1-3 gram alpha-linolenic acid for a 2000-kcal diet)
In 2013-2014, Americans 2 years of age and older consumed about...
11% of their total energy from saturated fat, 12% from monounsaturated fat, and 8% from polyunsaturated fats.
Long-chain fatty acids have...
14-24 carbons.
Short-chain fatty acids have...
2 to 4 carbons.
Total fat recommendations:
20-35% of total calories (45-75 grams total fat for a 2000 kcal)
Linoleic acid recommendations:
5-10% of total calories (11-22 grams linoleic acid for 2000 kcal diet)
Medium-chain fatty acids have...
6 to 12 carbons.
Omega-3 Fats May Reduce the Risk of Developing:
Alzheimer's disease, Arthritis, Certain cancers, Dental disease, Depression, including postpartum depression, heart disease, preterm birth.
According to the 2015-2020 Dietary Guidelines,....
Americans should keep their trans fat intake as low as possible while eating a healthy diet.
Why is it important to understand the differences between saturated, unsaturated, and trans fats and to identify foods that contain high amounts of these fats?
Because populations that consume diets rich in saturated fat and trans fat have higher incidence of developing CVD, certain types of cancer, and other forms of chronic disease than populations whose diets contain more unsaturated than saturated fat.
Thus, people with homocysteinuria have a higher risk of developing...
CVD than persons who do not have the condition.
Modifiable Risk Factors
Diabetes mellitus, Elevated blood cholesterol (LDL), Excess body fat, Hypertension, Physical inactivity, Tobacco use or exposure to tobacco smoke, Unhealthy diet, Untreated sleep apnea
Rich food Sources of Omega-3 Fats:
Herring, salmon, sablefish, anchovies, tuna, bluefish, sardines, catfish, striped bass, mackerel, trout, halibut, pollock, flounder, shrimp, mussels, crab, flaxseed (oil), walnut (oil), Canola (oil), Soybean (oil), Walnuts flaxseeds, algae.
Maintaining a healthy body weight is particularly important for American Indians and...
Mexican-Americans because members of these ethic groups have the highest rates of gallbladder disease in the US
According to the American Heart Association and the...
National Cholesterol Education Program, the desirable range for total blood cholesterol is less than 200 mg/dL.
Certain animal foods, especially beef and dairy foods, contain higher percentages of...
SFAs than most plants fats.
Essential Fatty Acids
The body cannot linoleic acid to arachidonic acid and alpha-linolenic acid to two other omega-3 fatty acids, eicosapentaenoic, and docosahexaenoic acid (DHA).
Major Functions of Lipids in the Body
The body uses fats and other lipids to: -Absorb fat-soluble vitamins and phytochemicals -Cushion the body against bumps and blows -Form and maintain cell membranes -Form body contours -Insulate the body against cold temperatures -Produce steroid hormones -Provide and store energy (triglycerides)
Consider what happens when you mix vinegar and olive oil to make a vinaigrette salad dressing.
Vinegar is 95% water, oil is 100% lipid. Therefore, the oil does not dissolve in the water to make a solution. Additionally, oil is less dense than water, so it rises to the top of the vinegar in small globules. The oil globules join together to form an oily layer that floats on the vinegar until the mixture is shaken. Shaking the ingredients mixes them temporarily. When left undisturbed, the oil and vinegar separate, hence, they saying, "Oil and water don't mix."
The liver uses cholesterol to form very-low density lipoprotein (VLDL). Triglycerides comprise most of...
a VLDL's volume. The liver releases VLDL into the bloodstream, and the cells that line capillaries release LPL that breaks down the triglycerides into fatty acids and glycerol.
Trans fatty acids are less likely to undergo oxidation,...
a chemical process that alters the compound's structure. When oxidized, the fat in food becomes rancid and develops an unappetizing odor and taste. Unsaturated fatty acids that have the cis double-bond arrangement, especially polyunsaturated fatty acids, are very susceptible to oxidation.
Atherosclerosis contributes to the development of hypertension....
a chronic condition characterized by abnormally high blood pressure that persists even when the person is relaxed.
Gaucher disease is caused by...
a deficiency of an enzyme involved in lipid metabolism.
When the gallbladder is removed or does not function properly, the...
affected individual digests fat less efficiently. If the gallbladder is damaged or removed, bile drips directly from the liver into the duodenum.
Lipids dissolve in organic solvents such as....
alcohol and acetone, but most lipids are insoluble in water.
The development of CVD involves chronic inflammation. The liver responds to infection and inflammation by producing...
and releasing high-sensitivity C-reactive protein (hs-CRP), simply referred to as C-reactive protein or CRP, into the bloodstream
Other foods (of food ingredients) derived from animals are high in cholesterol and saturated fat. Thus, limiting consumption of...
animal foods can help reduce dietary cholesterol and saturated fat intakes.
Cholesterol is found only in foods derived from....
animals; Egg yolk, liver, meat, poultry, and dairy products made from cream or whole milk are rich sources of the lipid.
Linoleic acid and alpha-linolenic acid
are 18-carbon PUFAs. Linoleic acid has two double bonds. Alpha-linolenic acid has three double bonds.
Modifiable risk factors generally involve lifestyle practices that can...
be changed, such as smoking and lack of physical activity.
Saturated fatty acid
because each carbon within the chain is saturated, that is, completely filled with hydrogen atoms.
Despite the ban on PHOs, trans fat is not likely to disappear completely from American's diet....
because some foods naturally contain small amounts of this type of fat.
Thus, if a person eats a high-fat meal, there will not be enough...
bile available in the GI tract to digest all the fat. The undigested fat is excreted in the feces.
If the stone moves out of the duct, the discomfort ends, but in some cases, the duct remains blocked and...
bile backs up into the liver or pancreas. Cholecystectomy, a surgical procedure that removes the diseased gallbladder, is often necessary
Omega-3 fatty acid supplements are generally considered safe; however, doses higher than 3g/day may interfere with...
blood clotting and increase the risk of strokes Therefore, consumers should check with their physician before taking fish oil supplements.
People can learn how much trans fat is in a serving of most packaged foods...
by reading the ingredient list and Nutrition Facts panel that on the product's label.
When blood triglyceride levels are too high (>150 mg/dL), people should reducing their intakes of refined carbohydrates, such as...
candy, pastries, and sugar-sweetened soft drinks. Alcohol intake also increases the concentration of triglycerides in blood, so consuming less alcohol may help reduce a person's blood level of this lipid in blood.
In biological systems, common fatty acids have an even number of...
carbon atoms.
Healthy arteries have a smooth lining. When the arterial lining is injured, a...
cascade of events begins that overtime, results in atherosclerosis. The immune system responds by producing inflammation of the injured arterial lining.
Secretin stimulates the liver to produce bile and...
causes the pancreas to secrete bicarbonate-rich pancreatic juice, which is necessary to create an alkaline environment in the small intestine.
In some individuals, however, PUFAs also reduce blood levels of total...
cholesterol and blood LDL cholesterol. Nevertheless, PUFAs tend to be healthful because they do not promote atherosclerosis.
Most adults do not need to consume dietary sources of...
cholesterol because the liver can make enough cholesterol to satisfy the body's needs.
SFA alters the structure of liver cell membranes so they no longer function properly. As a result, the liver removes less...
cholesterol from the bloodstream. Thus, most SFAs increase total blood cholesterol levels by raising concentrations of both LDL and HDL cholesterol.
Furthermore, the physician may request a lipoprotein profile, a specific series of blood tests, to...
evaluate total serum cholesterol levels, as well as serum HDL cholesterol, LDL cholesterol, and triglyceride levels. Patients should request a copy of the laboratory results and keep them along with others in their personal "medical file" for future reference
Fatty red meats such as beef rib steaks are often more tender and...
expensive than leaner cuts such as chuck roasts.
One yolk, from a large egg, contains abut 5 g f fat and 186 mg of cholesterol. To reduce cholesterol consumption, many Americans eat...
fewer fresh eggs than in the past. Whole eggs, however are often ingredients in commonly eaten foods such as salad dressings, noodles, frozen custards, sauces, and baked goods.
Early research suggested that supplements of omega-3 fatty acids, such as...
fish oil, had a beneficial impact on heart disease risk. However, more recent studies have not provided convincing evidence that omega-3 fatty acids protect against heart disease.
When a blood clot forms too easily, it can result in a thrombus, a...
fixed bunch of clots that remain in place and disrupt blood flow. The thrombus partially closes off an artery's lumen. IF this condition occurs in an artery that nourishes the heart, the heart muscle supplied by the artery does not receive enough oxygen and nutrients to function properly
Lipids also provide nonnutritional benefits such as enhancing....
food flavor, texture, and aroma. Whether fat occurs naturally in food or is added to it, this nutrient often makes food taste more appetizing. For example, people used to consuming whole milk, which is about 3.25% fat by volume, will recognize the difference fat makes to "mouthfeel" when they drink fat-free milk that contains less than 0.5% fat.
Additionally, chemically unstable substances (radicals) can damage LDL...
forming oxidized LDL.
Other signs of essential fatty acid deficiency include...
scaly skin, hair loss, and poor wound healing. The Adequate Intake (AI) for alpha-linolenic acid 1.6 g/day for men and 1.1 g/day for women. The AI for linoleic acid is 17 g/day for men and 12 g/day for women who are between 19 and 50 years of age. These amount cna be met with foods made with 2 to 3 tablespoons of vegetable fat daily, especially products made with canola and soybean oils, and meals that contain fatty fish, such as salmon and tuna at least twice a week.
Using butter occasionally is unlikely to clog one's arteries. People can modify their food...
selection and preparation practices to reduce their intakes of dietary fat, especially "unhealthy" fats.
Indeed, heart disease kills someone in the US about once every 84 seconds. This section focuses on dietary and other lifestyle practices that...
set the stage for developing heart disease and other forms of cardiovascular disease
If a person's blood lipid levels are too high and the levels have remained elevated even after making these lifestyle modification, he or she....
should discuss additional treatment options with his or her physician. Millions of Americans take a class of prescription drugs called statins to reduce their elevated blood lipid levels.
Physical inactivity and excess energy consumption contribute to weight gain. Engaging in moderate-intensity physical activity at least...
5 days a week and balancing energy intake with energy expenditure each day can help people achieve and maintain healthy body weights.
The average American consumes....
80 g of fat per day.
Triglycerides comprise about....
9.5% of lipids in the food and in the human body. Body fat is largely composed of stored triglycerides.
Omega-3 Fats May Improve:
Immune function, Cognitive development in infants, Rheumatoid arthritis symptoms.
The cholesterol carried by LDL (LDL cholesterol) is often referred to as "bad" cholesterol, because...
LDL conveys the lipid to tissues, including cells in the arterial walls that make atherosclerotic plaques.
Most lipids have fatty acids in their structures.
They provide energy for muscles and most other types of cells. A fatty acid is comprised of a hydrocarbon chain, a chain of carbon atoms bonded to each other and to hydrogen atoms. One end of the fatty acid chain has a carbon molecule with three hydrogen atoms attached to it. This part of the molecule is called the omega or the methyl end. The other end of fatty acid molecule forms a carboxylic acid.
Most lipids are completely insoluble in water.
This characteristic makes lipid digestion, absorption, and transport more complicated than that of carbohydrates because these three processes involve considerable amounts of water.
Lipases
Triglycerides and phospholipids need to be broken down by these fat-digesting enzymes before they can be absorbed.
Important exceptions are tropical oils such as coconut and palm oils.
Tropical oils contain more saturated than unsaturated fatty acids.
Cells use three vitamins-B6, folate, and B-12 to convert homocysteine into safer compounds. Some people have homocyteinuria...
a group of conditions caused by gene mutations that result in the accumulation of homocysteine in their blood stream. Higher than normal blood levels of homocysteine may injure arterial walls.
FDA determined that PHOs posed...
a health risk, and the agency banned their use in foods. This ban will go into effect in 2018.
In the US, nearly 31 million adults have total cholesterol levels greater than 240 mg/dL. Even if a person's total cholesterol level is below 200 mg/dL, he or she may still have...
a high risk of developing atherosclerosis. The reason is that the amounts of certain lipoproteins in blood, particularly LDL and HDL, are critical risk factors than is total cholesterol.
Nearby cells can then pick up the fatty acids and glycerol molecules to use for energy. 10 to 12 hours after...
a meal, most chylomicrons have been reduced to small cholesterol-rich remnants.
To prevent steatorrhea and maximize fat absorption, an individual with....
a missing or damaged gallbladder should eat smaller, more frequent meals and avoid high-fat meals.
Trans fats
are unsaturated fatty acids that have at least one trans double bond in their chemical structure, rather than the more common cis configuration.
Omega fats
are very important in human nutrition. The omega end of the fatty acid chain and note the position of the first double bond.
Lipoproteins
are water-soluble structures that transport lipids through the bloodstream.
Certain arteries are more commonly damaged by atherosclerosis; in addition to the arteries of the heart and brain....
arteries of the kidneys, retina, and legs are vulnerable. When atherosclerosis occurs in the common carotid arteries in the neck, blood flow to the brain is decreased, and clots can form that travel to the brain, causing a stroke.
When a plaque rupture (tears open), repairing the rupture also involves....
clot formation and such blood clots can be life threatening. Blood clotting is a healthy response to blood vessel injury that prevents excessive bleeding.
Genetics (family history) is a major risk factor for atherosclerosis and CVD that cannot be modified. A person's genes may...
code for various physical conditions that increase risk of heart disease, such as hypertension and diabetes.
VLDLs shuttle lipids to adipose (fat)cells, which remove the triglycerides from VLDL and store them. As blood triglyceride levels increase...
concentrations of HDL tend to decrease. Some medical researchers think elevated triglyceride levels contribute to the development of CVD, but the mechanisms are unclear at this point.
CCK signals the pancreas to secrete digestive enzymes, including pancreatic juice, which is necessary to...
create an alkaline environment in the small intestine. It also signals the pancreas to secrete digestive enzymes, including pancreatic lipase, into the duodenum of the small intestine.
AIDS, for example, is caused by human immunodeficiency virus (HIV); a person cannot...
develop AIDS without being infected with HIV. Atherosclerosis, however, is an extremely complex disease process.
In the future, young people could undergo genomic testing to determine their risk of...
developing atherosclerosis well before the symptoms of the condition appear.
A healthy ratio of total cholesterol to HDL cholesterol is less than 3.5:1. IF this man thinks his risk of...
developing heart disease is low because his blood cholesterol level is less than 200 mg/dL, he is incorrect.
Despite the added challenges, the average healthy adult....
digests, absorbs, and utilizes about 98% of fat that is consumed.
Steaming meats and vegetables is a cooking method that...
does not require adding fat during preparation, Stir-frying pieces of raw vegetables, meat, fish, shellfish, and poultry in small amounts of hot vegetable oil cooks them quickly and preserves micronutrients.
Cell membranes are composed of a...
double layer that is mostly phospholipids. The chemical structure of the phospholipids enables the membrane to be flexible and function properly. Phospholipids are also needed for normal functioning of nerve cells, including those in the brain.
ADMRs have been established for the essential fatty acids. In adults...
linoleic acid should provide 5% to 10% and alpha-linolenic acid 0.6 to 1.2% of total daily kcal. Americans consuming a typical Western diet regularly meet these essential fatty acid recommendations.
As the food enters the stomach, the organ's acidic environment activates the...
lipase, enabling some lipid breakdown to occur.
To reduce the risk of developing CVD, the Dietary Guidelines and American Heart Association guidelines....
recommend limiting saturated fat intake to less than 10% of total energy by replacing foods that are rich sources of long-chain saturated fat with foods that contain high amounts of unsaturated fat.
People may also reduce their risk of developing CVD by making other dietary changes. Eating foods that are rich sources of fiber, particularly soluble fiber can....
reduce LDL cholesterol levels without lowering beneficial HDL cholesterol levels.
Fatty acids can be...
saturated or unsaturated.
The lack of the enzyme results in lipid accumulation in bone marrow and some organs, including the liver, kidneys, lungs spleen, and brain... Although Gaucher disease is fatal...
some individuals with the inherited condition survive to the early teenage years and young adult hood.
Additionally, genes may influence the way in which the circulatory and immune systems respond to a diet. Thus...
some people may be protected against the development of CVD, whereas other persons with similar diets develop serious arterial plaques early in life and die prematurely of CVD as a result.
Although cholesterol is not metabolized for energy, cells use it to synthesize a variety of substances, including....
steroid hormones, such as vitamin D, cortisol, aldosterone, testosterone, estrogen, and progesterone.
Cholesterol is the most well-known
sterol.
The small intestine, however, it the primary site of lipid digestion. As the fatty chyme leaves the...
stomach and enters the small intestine, it stimulates certain intestinal cells to secrete the hormones cholecystokinin and secretin.
Chylomicrons are too large to leave the villus via the bloodstream. Chylomicrons are...
too large to leave the villus via the bloodstream. Chylomicrons are too large to leave the villus via the bloodstream, so they pass through the larger openings of a lacteal, the lymph vessel located in the center of each villus.
A neurotransmitter is a chemical that...
transmits messages between the nerve cells.
Taking these steps can also reduce blood LDL and...
triglyceride levels and raise blood HDL levels.
Because of the time required to clear the chylomicrons, a 10-12 hour fast is...
necessary to obtain accurate measurements of lipids in the blood.
Additionally, when ground beef is browned in a pan, much of the fat can be...
drained before adding other ingredients to the meat.
People should limit their trans fat intake as much as possible. This can be accomplished by...
eating fewer solid fats, especially foods made with partially hydrogenated oils, such as stick margarine.
A person may be able to forestall CVD and live a longer, more satisfying life by reducing or...
eliminating modifiable risk factors for developing atherosclerosis. Diet, for example, influences the likelihood of developing atherosclerosis and is highly modifiable
The lymphatic system transports chylomicrons to the thoracic duct, where they...
enter the bloodstream through the left subclavian vein in the chest.
As chylomicrons circulate through the body, lipoprotein lipase, an...
enzyme in the walls of capillaries, breaks down the triglycerides in the chylomicron into fatty acids and glycerol.
In 2009-2010, the typical American consumed about 62 pounds of fat per year. Although the DRI committee has not...
established an RDA or AI for total fat intake (over 1 year of age), the Acceptable Macronutrient Distribution Range for fat is 20 to 35% of total caloric intake.
Fried foods, chips, and salad dressings are high in fat; bacon, sausage, hot dogs, luncheon meats, and hard cheese are also fatty foods. Nuts, including peanuts and almonds, have high....
fat content, but they generally contain high amounts of healthier monounsaturated fats
Fat-free milk actually contains less than 0.5% fat by volume, and...
fat contributes essentially no energy to the beverage. About 90% of the calories in cream chesses and about 100% of the calories in butter and margarine are from fat.
Although it is easy to peel greasy breading from fried fish or chicken, much of the...
fat that we eat is hidden in foods and beverages. For example, fat comprises only 2% of the milk's volume but contributes 37% of the beverage's calories
The process of digesting phospholipids is similar to that digesting triglycerides. A pancreatic phospholipase removes the...
fatty acid from the second position of the phospholipid molecule. The remaining structure is a phospholipid fragment.
People who are trying o reduce their energy intake should recognize that fat-reduced and fat-free foods are not "calorie-free". Food manufacturers often...
increase the amounts of added sugars in these products to improve taste and to compensate for reduced fat content
Age, sex, racial/ethnic ancestry, and family history are major, nonmodifiable risk factors for developing CVD, including heart disease. The risk of heart disease...
increases as people grow older, and men are more likely to have heart attacks than women.
Scientists are searching the entire set of human genes (genome) to locate genes...
involved in the development of atherosclerosis and to develop blood tests that identify biomarkers produced by the mutated genes.
An omega-3 fatty acid
is a PUFA with its first double bond at the third carbon from the omega end of the molecule.
Partial hydrogenation
is a food manufacturing process that adds hydrogen atoms to some unsaturated fatty acids in liquid vegetable oil. The process converts many of the oil's naturally occurring cis fatty acids. Oils that contained these artificial fats are called partially hydrogenated oils )PHOs).
A chylomicron
is a specific type of lipoprotein formed in enterocytes.
An omega-6 fatty acid
is also a PUFA, but its first double bond occurs at the sixth carbon from the omega end of the chain.
Trans fat recommendations:
keep intake as low as possible
Without bile's action, lipids would collect in a greasy film or aggregate into...
large globules within the lumen of the small intestine.
Several major risk factors for atherosclerosis involve....
lifestyle choices that can be modified, including hypertension, diabetes, and smoking
The typical American eats far more omega-6 foods than foods that contain omega-3 fatty acids. The essential omega-6 fatty acid...
linoleic acid, is found in vegetable oils used for frying and for making margarines and salad dressings.
When exposed to watery digestive juice, hydrophobic long-chain fatty acids, along with bile, cholesterol, fat-soluble vitamins, and other products of...
lipid digestion, pack together into round structures called micelles. The bile salts create a shell around each micelle, which allows the small lipid clusters to remain suspended in the watery digestive juices.
For the average adult, about two-thirds of the total body cholesterol is made in the...
liver and one-third is consumed through food sources.
Certain lipoproteins carry lipids from the liver to cells. Other lipoproteins convey lipids from cells to the...
liver, where they may be converted into new compounds.
This particular type of LDL is not beneficial because it is taken up by immune system cells called...
macrophages, which over time, become "foam" cells.
Because the bile salts are then excreted in feces, new bile must be...
made from cholesterol, reducing blood cholesterol levels.
Twenty million Americans suffer from gallstones that develop in their gallbladders or bile ducts...
making gallstones one of the most common digestive diseases in the US.
Average cholesterol intake during that same period was 325 mg/day for...
males and 229 mg/day for females.
Instead of relying on PHOs to extend the shelf life of products...
manufacturers can preserve fat and other ingredients in foods by adding antioxidants to them. Certain food additives, vitamins, and plant pigments function as antioxidants
Some signs of lipid storage diseases include an enlarged spleen or liver, swollen abdomen, skeletal disorders, and swollen lymph nodes. The...
most common lipid storage disorder, which affects between 1 in 50,000 and 1 in 100,000 Americans is Gaucher disease.
Thus, more research is needed to clarify the pros and cons of following diets that contain high amounts of...
omega-6 fatty acids. Eating foods that supply omega-3 fatty acids reduces the risk of developing heart disease to a greater extent than does eating foods that supply omega-6 fatty acids.
When a gallbladder that contains stones contracts or when a large gallstone lodges in...
one of the ducts that carry bile from the gallbladder to the small intestine, the person feels considerable pain in the right upper part of the abdomen.
The liver releases protein "Shells" into the bloodstream that pick up cholesterol and...
other lipids that are released from cells. When they are filled with lipids, the shells are called high-density lipoprotein (HDL). Compared to the other lipoproteins, HDL has the most protein.
This section focuses on dietary and other forms of cardiovascular disease. Although...
people often establish poor lifestyle practices early in life, changing these practices at any age can reduce their chances of developing CVD.
Because their chemical structures are similar to cholesterol's....
plant sterols and stanols compete with cholesterol for intestinal adsorption, which reduces the amount of cholesterol that is absorbed. As a result, consuming foods that contain plant sterols and stanols may be an effective way to lower elevated blodd cholesterol levels, a risk factor for developing heart disease.
Exposure to secondhand smoke is also a risk factor for heart disease. Simply improving a smoker's diet is unlikely to...
reduce his or her risk of developing atherosclerosis; therefore, smokers should make every effort to quit using tobacco products.
Atherosclerosis results in decreased arterial blood flow and arteriosclerosis,....
reduced arterial wall flexibility (hardening of the arteries).
Monounsaturated fatty acids (MUFAs) generally lower blood LDL cholesterol without...
reducing HDL cholesterol levels. As with the action of MUFAs, diets containing high amounts of polyunsaturated fat acids (PUFAs) may reduce blood levels of total cholesterol and blood LDL cholesterol.
Trans fats also raise blood cholesterol levels. However, trans fats raise LDL cholesterol while...
reducing beneficial HDL cholesterol. Cholesterol intake may also raise some individuals' blood LDL cholesterol levels
Stains interfere with the liver's metabolism of cholesterol, effectively reducing LDL cholesterol and triglyceride levels as a result. Stains are..
relatively safe when taken as directed and with regular monitoring by one's physician.
Consumers can reduce their intakes of trans fats by using soft (tub) or liquid margarines, or trans fat-free spreads that...
resemble margarine, instead of stick margarine.
Zetia is a drug that works differently from a statin Zeta inhibits intestinal absorption of cholesterol and, as a...
result, lowers LDL cholesterol levels. However, question have been raised about about the medication's safety, particularly when it is taken with other cholesterol-lowering medications
When a thrombus completely blocks blood flow to a section of the heart muscle, the muscle dies...
resulting in a myocardial infarction, which is commonly called a "heart attack". Sudden death can result from a severe myocardial infarction
To calculate risk of having a heart attack during the next 10 years, use the...
risk assessment tool at www.heart.org.
Studies designed to determine the effects of dietary cholesterol on blood cholesterol levels and...
risk of heart failure, heart attack, and stroke have had mixed results.
In general, scientific evidence suggest that dietary cholesterol levels and...
risk of heart failure, heart attack, and stroke have had mixed results. In general, scientific evidence suggests that dietary cholesterol does not have as much effect on blood cholesterol levels as dietary saturated fat.
Many Americans have replaced butter with partially hardened vegetable oil margarines because of concern over butter's cholesterol and...
saturated fat content. Compared to butter, a serving of margarine provides more unsaturated fat, less saturated fat, and less cholesterol.
According to the Dietary Guidelines, adults should consume less than 10% of their total calories from...
saturated fatty acids and limit their fat and cholesterol intakes to as little as possible.
Furthermore, those who do not smoke should avoid breathing secondhand smoke, and...
those considering using e-cigarettes should be aware that research on the safety of e-cigarettes is limited; therefore, such products should not be considered a safe alternative to traditional tobacco products.
Trans fatty acids resemble...
saturated fatty acids and provide properties of long-chain saturated fatty acids to foods that contain them. Fats that contain a high proportions of PHOs are more solid at room temperature than those with a high proportion of cis fatty acids. As a result of partial hydrogenation process, vegetable oil can be made into vegetable shortening ( a solid fat) or shaped into sticks of margarine.
Essential fatty acids are necessary in...
small amounts for good health. Infants require DHA and EPA for nervous system development, and babies do not grow property when their diets lack essential fatty acids.
Whole milk and whole-milk products, butter, and meat naturally contain....
small amounts of trans fats. Although the body can use trans fatty acids for energy, these lipids are not essential, and medical researchers have not discovered any positive health effects from consuming them. In the body, trans fat raise blood levels of an unhealthy form of cholesterol, which increases the risk of heart disease.
However, margarine made from partially hydrogenated vegetable oil contains considerable amounts of unhealthy trans fatty acids. The amount of saturated and trans fat in...
soft margarines is less than the amount in hard margarines or butter.
Lipids are structural components of the plasma membrane that....
surrounds each cell. The layer of fat under the skin stores energy; insulates against cold temperatures, protects against minor bruising, and contributes to the body's contours.
To obtain beneficial long-chain omega-3 fatty acids such as DHA, the Dietary Guidelines recommend....
that Americans eat at least 8 ounces of seafood (fish and shellfish) a week, such as sardines, salmon, tuna, and trout.
Atherosclerosis and arteriosclerosis are terms...
that are often used interchangeably; however, arteriosclerosis is actually a symptom or by-product of atherosclerosis.
A thrombus or part of a plaque that breaks free and travels through the bloodstream is an embolus. An embolus...
that lodges in an artery can create the same serious consequences as a stationary thrombus
In 2014, heart disease and stroke together accounted for nearly half of all deaths. Indeed, heart disease kills someone in...
the US about once every 84 seconds.
LDL transports cholesterol and other lipids to tissues. Cell remove LDL from...
the bloodstream and use its lipids to make vital substances and structures.
The amino acid homocysteine may be associated with CVD. Amino acids are...
the chemical units that comprise proteins, but the substance s a toxic by product of protein metabolism
As a result, the affected person experiences bouts of chest pain, especially when...
the heart beats faster, such as during intense emotional states or physical activities
Fatty acids are identified not only by their chain length and number of double bonds, but also...
the location of the double bonds in the carbon chain.
When miclles come close to their villi their contents diffuse into absorptive cells (enterocytes). Under normal conditions....
the small intestine digests and absorbs nearly all of the triglycerides and phospholipids in food. but only about 50% of dietary cholesterol is absorbed.
HDL is...
the smallest and densest of these lipoproteins, because it transports more protein and less lipids than the other lipoproteins.
CCK also triggers the gallbladder to release stored bile and...
the sphincter that controls the flow of bile and pancreatic juice into the duodenum to open.
The liver clears these remnants from the bloodstream and uses....
their contents to synthesize new lipids and other lipoproteins that are released into the general circulation.
Lipoproteins play major major roles in the development of atherosclerosis. HDL conveys lipids away from tissues and to the liver, where...
they can be processed and eliminated. Thus, the cholesterol carried by HDL (HDL cholesterol) is often called "good" cholesterol because it does not contribute to plaque formation
Short-and medium chain fatty acids diffuse into the absorptive cells of villi, where...
they enter the capillary network (bloodstream). Absorption of long-chain fatty acids, however, requires additional steps
Most foods contain fats with both saturated and...
unsaturated fatty acids. Some commonly consumed fats have 180carbon fatty acids in their hydrocarbon chain.
Polyunsaturated fatty acids (PUFAs)
unsaturated, but they have two or more double bonds in their hydrocarbon chains.
hydrophilic
water loving; attracts water
To determine a person's risk of developing atherosclerosis, it is a good idea to have regular medical checkups in...
which a physician checks the patient's blood pressure and listens to blood flow in the carotid arteries. Such tests assess whether the arteries are becoming blocked.
Under conditions in which blood LDL concentration is high, inflammation triggers certain...
white blood cells in arteries to become heavily laden with oxidized LDL particles ("foam cells"). The cholesterol-rich foam cells become trapped in the artery wall and overtime, contribute to the formation of arterial plaques. An arterial plaque is a fatty buildup in the artery.