Nutrition Chapter 6: Lipids, Triglycerides, Phospholipids and steroids
LIpases
enzymes that break down lipids
homocysteinuria
a group of conditions caused by gene mutations that cause homocysteine to accumulate in the blood
Cardiovascular disease (CVD)
a group of diseases that affect the heart and blood vessels; includes coronary artery disease, stroke and disease of the blood vessels.
Eicosanoids
a group of long-chain acids with hormone like functions
Embolus
a thrombus or part of a plaque that breaks free and travels through the bloodstream
phospholipid
a type of lipid needed to make cell membranes and for proper functioning of nerve cells;chemically similar to a triglyceride except that one of the fatty acids is replaced by a chemical group that contains phosphorus. -partially water soluble
chylomicron
a type of lipoprotein formed in enterocytes to transport lipids through the bloodstream.
where are plant sterols and stanols found?
grains fruits vegetables nuts seeds legumes
Cis fatty acids
most naturally occurring unsaturated fatty acids hydrogen atoms of the double-bonded carbons are on same side of hydrocarbons chain
Stroke
occurs when a clot blocks an artery in the brain; brain cells that are nourished by the vessel die.
VLDLs
shuttle lipids to adipose tissue cells (cells that store triglycerides)
where does the majority of lipid absorption occur?
small intestine
Enterohepatic circulation
the process that recycles bile salts in the body which is incorporated into new bile
How are long-chain fatty acids absorbed?
requires additional steps. they are packed together with bile, cholesterol and fat-soluble vitamins in micelles. -then when micelles comes close to villi, there contents diffuse into absorptive cells
AHA recommendations for reducing the risk of developing CVD:
sat fat <10% of total kcals limit trans fat intake omega-6 fatty acids 5-10% total energy intake 8 oz of cold-water fatty fish/week limiting consumption of animal foods
Lymphatic system's role
transports chylomicrons to the thoracic duct; where it will enter the bloodstream at the left subclavian vein and circulate through the body
cascade of events following injury of arterial lining:
injured arterial lining becomes inflamed> white blood cells become laden with oxidized LDL particles> arterial plaques (fatty buildup in the artery) form interference of circulation > clots more likely to form
Plants containing soluble fiber
interfere with cholesterol and bile absorption which helps reduce blood cholesterol levels
Oil
less dense than water, so it will rise to the top of a solution
medium-chain fatty acids have how many carbons?
6-12
AI's for alpha-linolenic acid
1.6g/day for men 1.1 g/day for females
long-chain fatty acids have how many carbons?
14-24
olive oil
a rich source of MUFAs
Atherosclerosis
a long-term disease process in which plaque builds up inside arterial walls
Carotid Arteries
convey blood to the brain **atherosclerosis in these arteries can result in reduced blood flow to the brain and increase the risk of stroke
lipid storage diseases
genetic conditions that cause lipid accumulation in cells damaging tissues.
Gallstones
hard particles that can accumulate in the gallbladder or become lodges in one of the ducts carrying bile from the gallbladder to the small intestine
Cholecystokinin (CKK)
hormone that stimulates the gallbladder to release bile and the pancreas to secrete digestive juices
two parts of a phospholipid
hydrophobic end (will not dissolve in water) hydrophilic end (water loving)
Pancreatic Lipase
the digestive enzyme that removes two fatty acids from each triglyceride molecule
Omega
the end of a fatty acid containing a methyl group
hydrogenation
the food manufacturing process that adds hydrogen atoms to liquid vegetable oil, forming trans fat -these foods can be stored for longer because they are less likely to undergo oxidation -raise "bad" cholesterol in the blood -increases risk of heart disease
After absorption:
the fragments are reassembled into triglycerides and phospholipids.
Fat malabsorption
the impaired fat absorption; symptoms include diarrhea, steatorrhea and rapid weight loss
Gaucher disease
the most common lipid storage disease; caused by a deficiency of the enzyme glucocerebrosidase
steatorrhea
the presence of lipid in the stool -can occur if gallbladder is diseased or removed
lipoproteins
play roles in the development of atherosclerosis
hydrocarbon chain
a chain of carbon atoms bonded to each other and to hydrogen atoms.
Prostaglandins
a class of eicosanoids that produce a variety of important effects in the body.
Lipids
a class of nutrients that do not dissolve in water; triglycerides, phospholipids and sterols they dissolve in organic substances
Stearic acid
an 18-carbon saturated fatty acid
homocysteine
an amino acid that may play a role in the development of atherosclerosis
Lipoprotein lipase
an enzyme in capillary walls that breaks down the triglycerides -nearby cells pick up fatty acid s and glycerol to use for energy
carboxylic acid
an organic molecule with a carboxyl group
trans fats
are unsaturated fatty acids that have a double-bond hydrogen atoms of the double bonded carbons are on opposite sides of hydrocarbon chain
will cause HDL levels to decrease
blood concentrations of triglycerides increasing (this may contribute to CVD)
how are fatty acids identified?
by number of carbon atoms bonded and the type of bond between the carbon atoms
Plant sterols and stanols
chemicals found in plants that are structurally similar to cholesterol (these in mass, can help lower Cholesterol levels)
Bile Salts
components of bile; aid in lipid digestion and emulsification
how are short- and medium-chain fatty acids absorbed?
diffuse into the absorptive cells of the villi to enter into the capillary network
other dietary recommendations:
eat soft or liquid margarines trim away fat from meat consume fat-free milk eat food rich in fiber consume less alcohol engage in moderate-intensity physical activity 5 days/week
Where is cholesterol found?
egg yolk liver meat poultry dairy products
Essential fatty acids
fatty acids that must be supplied by the diet; linoleic and alpha-linolenic acid are both essential fatty acids
Thrombus
fixed bunch of clots that remain in place and disrupt blood flow. (partially closes off artery's lumen) **if in heart, person experiences bouts of chest pain.
Myocardial infarction
heart attack-occurs when a thrombus completely blocks blood flow to the heart muscle
Sterols
lipids that have a more chemically complex structure than a triglyceride or fatty acid.
Liquid corn oil
contains a greater proportion of unsaturated than saturated fatty acids.
fat in beef and dairy products
contains more saturated than unsaturated fatty acids
processed foods and margarines
contribute to the largest amounts of trans fats
chronic inflammation can lead to
development of CVD
LDL
"bad" cholesterol conveys lipid to tissue
HDL
"good" cholesterol does not contribute to plaque formation
AI's for linoleic acid
17 g/day for men 12 g/day for women
AMDR for fat =
20-30%
Oxidized LDL
LDL that has ben damaged by free radicals and contributes to atherosclerosis
Arteriosclerosis
a condition that results from plaque build up inside arterial walls and is characterized by loss of arterial flexibility
Dietary Guidelines suggestions on foods:
you should emphasize foods that are rich in polyunsaturated and monounsaturated fatty acids (ie> fish, nuts, and vegetable oil)
Major functions of lipids in the body:
1. providing and storing energy 2. forming and maintaining cell membranes 3. producing steroid hormones 4. insulating the body against cold temperatures 5. cushioning the body against bumps and blows 6. forming body contours 7. absorbing fat-soluble vitamins and phytochemicals
short-chain fatty acids have how many carbons?
2-4
How much does fat contribute to the average American;s daily energy intake (DEI)
33%
essential fatty acids that are precursors to eicosanoids:
Arachidonic acid (AA) Eicosapentaenoic acid Docosahexaenoic acid
Saturated fatty acid (SFA)
a fatty acid that has each carbon atom within the chain filled with hydrogen atoms.
Monounsaturated fatty acids (MUFA)
a fatty acid that has one double bond within the carbon chain
Polyunsaturated (PUFA)
a fatty acid that has two or more double bonds within the carbon chain
Unsaturated fatty acid
a fatty acid that is missing hydrogen atoms and has one or more double-bonds within the carbon chain
Fatty acid
a hydrocarbon chain bound in lipids; one end of the chain forms a carboxylic acid, and one end forms a methyl group.
Cholesterol
a lipid found in animal foods; precursor for steroid hormones, bole and vitamin D
Monoglyceride
a lipid that has one fatty acid attached to a three-carbon compound called glycerol
Triglyceride
a lipid that has three fatty acids attached to a three-carbon compound called glycerol -comprises 95% of lipids in food and body -most contain a mixture of unsaturated and saturated fatty acids; with one type of fatty acid predominating
Diglyceride
a lipid that has two fatty acid attached to three-carbon compound called glycerol
Very-low-density lipoprotein (VLDL)
a lipoprotein made in liver that carries much of the triglycerides in the bloodstream
Low-density lipoprotein (LDL)
a lipoprotein that carries cholesterol into tissue. elevated levels is strongly linked to increased risk of CVD.
High-density lipoprotein (HDL)
a lipoprotein that transports cholesterol away from the tissues to the liver to be eliminated. low levels is linked to increased risk of CVD.
High-sensitivity C-reactive protein (hs-CRP)
a portion produced primarily by the liver in response to inflammation; a marker of CVD
Lipoprotein profile
a series of blood tests to evaluate total cholesterol, HDL and LDL and triglyceride levels. this helps determine a person's risk for developing atherosclerosis
emulsifier
a substance that helps water soluble and water insoluble compounds mix together (a phospholipid is an example of this because it has both a hydro-phobic & philic end )
Cholecyctetomy
a surgery to remove a diseased gallbladder
Glycerol
a three-carbon alcohol that forms the "backbone" of fatty acids
omega-6 fatty acid
a type of polyunsaturated fatty acid with the first double bond at the sixth carbon from the omega end of the molecule (linoleic acid)
Omega-3 fatty acid
a type of polyunsaturated fatty acid with the first double bond at the third carbon from the omega end of the molecule (alpha-linolenic acid)
choline
a water-soluble vitamin like compound and is a component of lecithin. -it is found in egg yolk, liver, wheat germ, parent butter and soybeans (used to form acetylcholine)
Oleic Acid
an 18-carbon monounsaturated fatty acid
Alpha-linolenic acid
an 18-carbon polyunsaturated fatty acid with 18-double bonds; an essential fatty acid.
Linoleic acid
an 18-carbon polyunsaturated fatty acid with two double bonds; an essential fatty acid