Chapter 5: Lipids
beta-oxidation
-first step in the production of ATP from fatty acids -breaks the carbon chain of FA into 2C units that form acetyl-CoA and release high energy e- that are passed to ETC
saturated fatty acid
a fatty acid in which the carbon atoms are bound to as many hydrogens as possible and which, therefore, contains no carbon-carbon double bonds
monounsaturated fatty acid
a fatty acid that contains 1 C-C double bond (C=C)
polyunsaturated fatty acid
a fatty acid that contains 2 or more C-C double bond
lipids
a group of organic molecules, most of which do not dissolve in water. They include fatty acids, triglycerides, phospholipids, and sterols
LDL receptor
a protein on the surface of cells that binds to LDL particles and allows their content to be taken up for use by the cells
apoprotein B (apo B)
a protein on the surface of the LDL particle that must bind to a receptor protein on the cell membrane called an LDL receptor in order for LDLs to be take up by cells
tropical oils
a term used in the popular press to refer to the saturated oils-coconut, palm, and palm kernel oil-that are derived from plants grown in tropical regions
gluconeogenesis
glycerol from triglyceride breakdown can be used to produce ATP or make glucose through this process
moderate drinking for women
no more than 1 drink per day
moderate drinking for men
no more than 2 drinks per day
extra lean meat
no more than 7.5% fat by weight grounds meat considered extra lean if no more than 10% of its weight is fat
if the first double bond in an unsaturated fatty acid occurs between the 3rd and 4th carbons (from omega, CH3 end) what is this fat said to be?
omega-3(w-3) fatty acid
if the first double bond in an unsaturated fatty acid occurs between the 6th and 7th carbons (from omega, CH3 end) what is this fat said to be?
omega-6(w-6) fatty acid
most common saturated fatty acids
palmitic acid (16 carbons) stearic acid (18 carbons)
alcohol consumption during pregnancy
-FAS/fetal alcohol effects -breast feeding: alcohol readily enters breast milk, concentrates within 1 hr of consumption -decreases milk production -flavours milk
emulsifiers
-substances that allow water and fat to mix by breaking large fat globules into smaller ones -phosphoglycerides are able to act as emulsifiers because they have the ability to mix with both water and fat
atherosclerotic plaque
-the cholesterol-rich material that is deposited in the arteries of individuals with atherosclerosis -consists of cholesterol, smooth-muscle cells, fibrous tissue, eventually calcium -an inflammatory response is initiated by an injury, WBC rush to the injured area, forming blood clots, and new tissue grows to heal the wound
hydrogenation
-the process whereby hydrogen atoms are added to the carbon double bonds of the unsaturated fatty acids, making them more saturated -the resulting fat has more of the properties of a saturated fat, such as increased stability against rancidity and a higher melting point
transportation of short and medium chain fatty acids
-they are water soluble -thy can be transported from the small intestine in the voodoo and delivered to cells throughout the body
what is the recommended percentage of kcal that we should get from fat?
20%-35%
DRI recommended fat intake
20-35% of total kcal for adults 30-40% for age 1-3 25-35% for age 4-18 less than 10% saturated fat polyunsaturated (omega-3 and omega-6) should be ~10% energy
how many kcal/g do fats and oils provide?
9 kcal/g
Trend of fat intake over the past 25 years
based on the CCHS, the amount of fat consumed by canadians has declined over the last 25 years. in 1978, Canadians consumed about 40% of their kcal from fat, this has declined to an average of 31%.
recommended dietary ratio of linoleic to alpha-linolenic acid
between 5:1 - 10:1
how is reverse cholesterol transport accomplished?
by the densest lipoprotein particles called high-density lipoproteins called high-density lipoproteins (HDLs)
fat substitutes
can be carbohydrate, protein, or fat-based
calculating energy from fat
fat provides 9kcal energy/gram energy from fat= grams of fat x 9kcal/g
primary type of lipid in our body
triglycerides
what happens to the IDLs that are left over after triglycerides are removed from VLDLs
- 2/3 are returned to the liver -rest are transformed in the blood to low-density lipoproteins -LDLs contain less triglyceride and therefore proportionally more cholesterol than VLDLs and are the primary cholesterol delivery system for cells
transportation of long chain lipids and cholesterol
-not soluble in water -cannot enter bloodstream directly -must be incorporated into lipoproteins -long chain fatty acids and mono glycerides are first assembled into triglycerides by the mucosal cell -the triglycerides are then combined with cholesterol, phospholipids, and a small amount of protein to form lipoproteins called chylomicrons -chylomicrons are transferred to lymphatic system and then enter the bloodstream w/o first passing through the liver
steps of lipid digestion
1. a small amount of lipid digestion occurs in the stomach due lipase produced in the mouth and stomach 2. the liver produces bile, which is stored in the gallbladder and released into the small intestine to aid in the digestion and absorption of fat 3. the pancreas produces the enzyme pancreatic lipase, which is release into the small intestine to break down triglycerides into fatty acids and glycerol 4. in the small intestine, the products of fat digestion and bile form micelles, which move close enough to the brush border to allow lipids to diffuse into the mucosal cells 5. inside the mucosal cells, fatty acids are reassembled into triglycerides and incorporated into lipid transport particles, which enter the lymph
recommended serving of fish per week
2 servings
diglyceride/triglyceride
2/3 fatty acids attached to glycerol
based on animal studies what the benefits of CLA?
CLA reduces body fat and body weight, promotes beneficial changes in blood lipid profiles, reduces blood pressure, reduces cancer risk, improves bone mass, and enhances immune function
AMDR
acceptable macronutrient distribution ranges
what initiates the inflammatory response?
an injury, such as when you cut tousled -WBCs, which are part of the immune system, rush to the injured area, blood clots form, and new tissue grows to heal the wound
possible risks with CLA
based on a small number of studies, CLA was found to promote oxidative stress, which may be detrimental to health and may have adverse effects on liver function, glucose metabolism, and breast milk production
High-density lipoproteins (HDLs)
circulate blood, picking up cholesterol from other lipoproteins and body cells -function as temporary storage site for lipid -some of the cholesterol in HDLs is taken directly to the liver for disposal -some is transferred to the organs that have a high requirement for cholesterol
problems with fat intake below 20%
increase probability that vitamin E and essential fatty acid intakes will be low and may contribute to unfavourable changes in HDL and triglyceride levels
where do HDLs originate from?
intestinal tract and liver
what food groups are the highest contributors of fat in the canadian diet?
meat and milk and alternatives -- they account for 31.6% and 17.9% of total fat, respectively
lean meat
meat,poultry, turkey, etc that has not been ground and contains less than 10% fat by weight ground meats are considered lean if no more than 17% of its weight is fat
scavenger receptors
proteins on the surface of macrophages that bind to oxidized LDL cholesterol and allow it to be taken up by the cell
most common drugs used to treat elevated blood cholesterol
statins: work by blocking cholesterol synthesis in the liver and by increasing the number of LDL receptors
risks associated with trans fats
when consumed in the diet, trans fats raise blood-cholesterol levels and increase the risk of heart disease
in an uninjured blood vessel what would the LDL particle do?
would no enter the artery wall, but rather would continue to the capillaries and then enter nearby tissue
cardiovascular disease
-2nd leading cause of death in canada, after cancer -accounts for ~30% of deaths -in general, populations that consume high-fat diets have a higher incidence of heart disease -populations that consume a diet high in omega-3 FA have a low incidence of heart disease
what is one drink in terms of alcohol
-350 ml of beer -150 ml of wine -50 ml of spirits
recommended intake for alpha-linolenic acid
-AI: 1.1g/day (women), 1.6 g/day (men) -can meet this requirement by eating 60ml of walnuts or 15 ml of cola oil or ground flaxseeds AMDR: 0.6-1.2% of daily energy
recommended intake for linoleic acid
-AI: 12g/day (women), 17g/day (men) -can meet this requirement by consuming 125 ml of walnuts or 30 ml of safflower oil AMDR: 5-10% of energy
moderate alcohol consumption and heart disease
-MAc may reduce stress, raise levels of HDL cholesterol, and reduce clotting, thus reducing risk of HD -greater effects then red wine is consumed
biological role of fatty acids
-PUFAs help to regulate blood pressure and blood clotting -essential fatty acids are important for growth, skin integrity, fertility, and the structure and function of cell membranes -fatty acids and glycerol can be used to produce energy in the form of ATP -Eicosanoids are made from omega-3 and omega-6 fatty acids
essential fatty acid deficiency
-a condition characterized by dry, scaly skin and poor growth that results when the diet does not supply sufficient amounts of the essential fatty acids -occurs when inadequate amounts of linoleic and alpha-lenolenic acid are consumed -symptoms include scaly, dry skin, liver abnormalities, poor healing of wounds, growth failure in infants -very rare disease b/c the requirement for essential fatty acids is well below the typical intake
cholesterol
-a lipid that consists of multiple chemical rings and is made only by animal cells -necessary in the body -not essential in the diet because it is manufactured by the liver -also part of the myelin coating on many nerve cells -needed to synthesize vitamin D in the skin, chalice acid (component of bile), some hormones, and cortisol -may increase the risk of heart disease when circulated in the blood at high levels
lecithin
-a phosphoglyceride composed of a glycerol backbone, two fatty acids, a phosphate group, and a molecule of choline -lecithink is a major constituent of cell membranes and is required for their optimal function -also used to synthesize the neurotransmitter acetylcholine
oxidized LDL cholesterol
-a substance formed when the cholesterol in LDL particles is oxidized by reactive oxygen molecules. it is key in the development of atherosclerosis because it contributes to the inflammatory process
rate of alcohol metabolism
-about 0.5 oz alcohol/hr -alcohol in blood increases if exceeds the rate of breakdown
health risks of alcohol use
-accident and fatalities -hangover -free radical damage -liver damage -decreased ADH resulting in increased urine output which in turn results in loss of zinc, calcium, potassium and magnesium -other chronic diseases of kidney and heart, pancreas, cancer, ulcers, sexual dysfunction, and infertility
Citric acid cycle
-acetyl-CoA (2C) combines with oxaloacetate (4C) to form a 6C molecule called citric acid -rxns of CAC then removed 1C at a time to produce CO2 -high energy e- from beta-ox and CAC are shuttled to the ETC (last step of cellular res)
lipoproteins
-act as transport particles for water insoluble lipids -particles containing a core of triglycerides and cholesterol surrounded by a shell of protein, phospholipids, and cholesterol that transport lipids in blood and lymph -transport dietary triglycerides, cholesterol and fat soluble vitamins from the small intestine, and stored of newly synthesized lipids from the liver
B vitamins and heart disease
-adequate intakes of B6, B12 and folic acid may help protect against HD because they keep blood levels of the a.a. homocysteine low -niacin is another B vitamin that may affect HD -when niacin is consumed in extremely high does, the nicotinic acid form of niacin can be used to lower blood cholesterol
"free" fatty acids
-adipose tissue releases fatty acids into the blood to use as a source of energy -referred to as free FA to emphasize they are not in the form of triglycerides
triglycerides
-aka triacylglycerols -the major form of lipid in food and the body -consist of three fatty acids attached to a glycerol molecule
amount of free fatty acids released
-amount of free fatty acids released is proportional to the amount of adipose tissue present in the body
trans fatty acid
-an unsaturated fatty acid in which the hydrogen atoms are on apposite sides of the double bond -has a higher melting point than the same fatty acid in the cis configuration
Cholesterol is considered a parent compound for steroid hormones, what are the 5 major classes?
-androgens -estrogens -progestins -mineralcorticoids -glucocorticoids
role of essential fatty acids
-cannot be made by body -essential fatty acids needed for: growth, skin integrity, fertility, nerve and brain function, and the structure and function of cell membranes
risks associated with high fat intake
-cardiovascular disease linked to high cholesterol intake, saturated fat and trans fat -the risk of certain types of cancer (breast, colon,prostate) have all been linked with high fat intake -obesity -diabetes -high blood pressure
fatty acid
-chain of carbon atoms with an acid group (COOH) at one end -other end is called the omega/methyl end (CH3) -physical properties depend on the length of the carbon chain and the type and location of the bonds between the C atoms
transport of lipids from the liver
-chylomicron remnants are disassembled and triglycerides from the remnant recovered -excess protein, CHO, or alcohol can be broken down as well and used to make triglycerides or cholesterol -triglycerides in liver are incorporated into lipoprotein particles called very-low-density lipoproteins -Cholesterol synthesized in the liver or delivered in chylomicron remnants can also be incorporated into VLDLs or used to make bile -VLDLs transport lipids out of the liver and deliver triglycerides to body cells -lipprtein lipase breaks down the triglycerides in VLDLs so that the fatty acids can be taken up by surrounding cells -after triglycerides are removed from VLDLs, smaller intermediate-density lipoprotein (IDL) remain
alcohol
-class of organic compounds containing hydroxyl groups -ethyl alcohol is the ingredient in beer. wine and liquor -produced by microbial fermentation of CHO -provides 7kcal/g
where do most of the trans fats that we eat come from?
-comes from products that have undergone hydrogenation -after hydrogenation occurs, some of the double bonds accept hydrogens and become saturated -during hydrogenation, only some of the bonds become saturated, some of those that remain unsaturated are altered, converting them from the cis to the trans configuration -the resulting product therefore, contains more trans fatty acids than the original oil
ketones
-created when there is not enough glucose (specifically acetyl-CoA) from fat breakdown to enter CAC -can be used as an energy source by muscle and adipose tissue -during prolonged starvation the brain adapts to use ketones to meet about 1/2 of its energy needs (needs glucose for other half)
dietary fat and obesity
-dietary fat thought to contribute to weight gain and obesity -fat has 9kcal/g which is almost twice as much as either carbs or protein. therefore a high fat meal contains more kcal in the same volume as a lower fat meal
dietary fat and colon cancer
-diets high in processed meats and red meat have been associated with an increased risk of colon cancer -diets high in omega-3 fats acids from fish are associated with a lower incidence of colon cancer -connection between dietary fat and colon cancer may be related to the breakdown of fat in the large intestine
what drives the formation of atherosclerotic plaque?
-driven by inflammation
production of ATP from ETC
-electrons are passed from beta-ox and CAC down to ETC, which is the last step of cellular res -molecules in this chain accept e- and pass them down the chain until they are finally combined with oxygen to form water -energy in these e- is then used to generate ATP
fat storage in adipose tissue
-excess energy consumed as fat can be transported directly from the intestines to the adipose tissue in chylomicrons -excess energy consumed as carbohydrate or protein must first go to the liver, where the carbohydrate and protein can be used to synthesize fatty acids -these FA are then assembled into triglycerides, which are transported to the adipose tissue in VLDLs -lipoprotein lipase at the membrane of cells lining the blood vessels breaks down the triglycerides from both chylomicron and VLDLs so the FA can enter the fat cells, where they are reassembled into triglycerides for storage
dietary cholesterol and heart disease
-excessive cholesterol intake increases risk of HD
what happens to CAC when there is insufficient oxaloacetate?
-fatty acids cannot enter CAC -form ketone bodies instead
dietary recommendations to reduce cancer risk
-follow Canada's food guide -eat regularly -fill 1/2 plate with vegetables, 1/4 with grains, 1/4 with meat and alternatives -watch portion sizes -plans meals and make gradual improvements to your diet -read nutrition labels
bile acids
-formed from cholesterol -once conjugated with taurine or glycine (in liver) they are secreted in the bile -solubilize phospholipids and cholesterol (detergents) -aid in digestion and absorption of fa and fat-soluble vitamins in the intestine
arachidonic acid
-found naturally in animal tissues -most of it is made from
long chain fatty acids
-greater than 1 2carbons -usually remain solid at room temp, higher melting points
alcohol rate of breakdown depends on
-health -genetics -body consumption -gender -age -frequency of alcohol consumption -fasting vs fed state (ADH is broken down during fasting)
results of high levels of HDL
-help prevent cholesterol from depositing in artery walls -associated with reduction in heart disease risk -referred to as "good" cholesterol
trans fatty acids and heart disease
-high trans fatty acid intake increases risk of HD -diets high in trans fat cause greater increase in HD than diets high in saturated fat -trans fatty acids promote synthesis of cholesterol in the liver -> may cause increases in LDL cholesterol -trans fat may also increase risk of HD by increasing inflammation
essential fatty acids
-humans are capable of synthesize most of the fatty acids our body needs from glucose or other sources -our body is not able to synthesize double bonds in the omega-6 and omega-3 positions -linoleic acid and alpha-linoleic acid are essential fatty acids -importnt for formation of phospholipids that give cells membranes their structure and functional properties
omega-6 fatty acids
-important for growth -skin integrity -fertility -maintain RBC structure
how does the atherosclerotic process begin?
-in response to an injury that causes changes in the lining of the artery wall -once this injury has occurred, the lining of the artery becomes more permeable to LDL particles, which migrate into the artery wall
effects of lifestyle factors on heart disease risk
-inactive lifestyle and cigarette smoking both increase risk of HD -dietary factors: high intake of saturated and trans fats, as well as cholesterol increase risk of HD
effect of genetics on heart disease risk
-individuals with a male family member who exhibited heart disease before age 55 -or female family member who exhibited heart disease before age 65 are considered to be at greater risk of HD
diabetes, high BP, obesity, blood-lipid levels effect on cardiovascular disease
-individuals with diabetes have an increased risk of developing heart disease - high levels of blood glucose that occur from obesity cause damage to blood vessels, initiating atherosclerotic events -elevated BP can increase risk by damaging blood vessels -high BP forces heart to work harder, causing it to enlarge and weaken over time -obesity increases the amount of work required by the heart and also increase BP, blood-cholesterol levels, and the risk of developing diabetes
what happens when blood sugar is low
-insulin is absent -hormone sensitive lipase is not suppressed and free fatty acids are released from adipose tissue into the blood -these FAs are taken up by tissue, and act as a source of fuel -spares glucose for the brain which cannot use free FA as a source of furl
plant foods and heart disease
-inverse relationship exists between consumption of fruits and vegetable and incidence of HD -fruits, veg, legumes are good sources of fibre, vitamins, minerals, and phytochemicals -soluble fibres reduce blood cholesterol and therefore reduce HD -vitamins, minerals, and phytochemical in plant foods protect against HD b/c many have antioxidant functions
what does the formation of the cap (during inflammatory response) do?
-it is a way of healing the injury -but if inflammation continues, substances secreted by immune system cells can degrade this cap -if the cap becomes too thin and ruptures, the material leaks out and causes blood clots to form -the clots can completely block the artery at that spot, or break loose and block an artery elsewhere
why is oxidized LDL cholesterol harmful?
-its presence promotes inflammation in a number of ways -it triggers the production and release of substances that cause immune system cells to stick to the lining of the artery and then to migrate into the artery wall -once inside these cells become large WBCs called macrophages which have scavenger receptors on their surface -scavenger receptors bing to and transport oxidized LDL cholesterol to the interior of the cell -as macrophages fill with more oxidized LDL cholesterol, they are transformed into cholesterol-filled foam cells -foam cells accumulate in the artery wall and then burst, depositing cholesterol to form a fatty streak
breast cancer
-leading form of cancer in women worldwide -approx 20,000 Canadian women diagnosed annually -more common in women age 50-69, women who have no children or had children later in life -more common in women with a family history
low-density lipoproteins (LDLs)
-lipoproteins that transport cholesterol to cells -elevated LDL cholesterol increases the risk of cardiovascular disease - "bad" cholesterol
acute effects of alcohol consumption
-liver breaks down 15 ml go EtOH/h = EtOH in 150 ml wine, 350 ml beer, 50 ml spirit -when alcohol intake exceeds that ability of the liver to break it down, alcohol intoxication or alcohol poisoning can occur -the circulating alcohol affects the CNS, breathing and HR
long term effects of alcohol use
-long term excessive alcohol consumption causes malnutrition: decreasing overall nutrient intake, causes primary malnutrition (low intake of CHO, thiamin, vitamin A/C), -causes secondary malnutrition by interfering with nutrient absorption, storage, metabolism and excretion (inflammation to GI organs, damage to intestinal lining limits absorption of thiamin, other B vitamins and vitamin C) -increases kcal intake which can lead to obesity
HDL and risk of cardiovascular disease
-low levels of HDL are associated with increased risk of cardiovascular disease -blood levels of triglycerides are a reflection of the amount of VLDLs in circulation and therefore higher levels of triglycerides are associated with increased risk of cardiovascular disease
phosphoglycerides
-major class of phospholipids -consists of a glycerol molecule, 2 fatty acids, and a phosphate group -fatty end of a phosphoglyceride is soluble in fat, whereas the phosphate end is water soluble -this allows phosphoglycerides to mix in both water and fat
role of fatty acids in synthesis of regulatory molecules
-make hormone like molecules that help regulate blood pressure, blood clotting, and other functions such as gene expression
dietary fat and cancer
-mediterranean women who rely on olive oil (source on monounsaturated fat) have a low incidence of cancer -omega-3 fatty acids from fish result in a protective effect -trans fats have been suggested to increase cancer risk
benefits of alcohol consumption
-moderate drinking: no more than 1 drink/day for women and 2 drinks/day for men -moderate drinking has a number of benefits including reduced risk for HD and stroke (higher HDL, lower fibrinogen) -antioxidant (red wine) -decreased stress
monoglyceride
-monoacylglycerol -one fatty acid attached to glycerol molecule
reverse cholesterol transport
-most body cells do not have a system for breaking down cholesterol -therefore it must be returned to the liver to be eliminated from the body
lipid function in structure and lubrication
-most lipids in the human body are triglycerides stored in adipose tissue -adipose tissue insulates body from temp changes and provides a cushion to protect internal organs against shock -lipids are important structural components at cellular level, particularly in the brain and NS (form an insulating coating around myelin sheath) -also important for lubricating body surfaces
arachidonic acid and DHA
-necessary for normal brain development in infants and young children
olive oil and heart disease
-olive oil is very high in monounsaturated fats -substituting monounsaturated fat from police reduces unhealthy LDL cholesterol without decreasing healthy HDL cholesterol
EPA and DHA
-omega-3 fatty acids that can be synthesized from alpha-linolenic acid -should be obtained directly from diet through consumption of fish
fatty acids
-organic molecules made up of a chain of carbons linked to hydrogen atoms with an acid group at one end -determine the physical properties and health effects of the triglycerides we consume
micelles
-particles formed in the small intestine when the products of fat digestion are surrounded by bile acids. they facilitate the absorption of fat
Effect that types of fat have on health
-populations that have higher intakes of fat from meats and dairy products, foods that are high in saturated fat and cholesterol, tend to have a higher incidence of heart disease and certain types of cancer than populations where intake of saturated fat and cholesterol is low -food sources that contain more saturated and trans fats are linked to increased risk of human health
why is fat needed in the diet?
-provide essential fatty acids -allow absorption of fat-soluble vitamins and phytochemical -provide energy
metabolism of alcohol
-quickly absorbed and used quickly (20% of consumed alcohol is absorbed in the stomach) -food slows down the absorption -alcohol enters the blood steam quickly -alcohol can cause dehydration -alcohol lost through lungs used to estimate blood alcohol -metabolized by the liver (fast): alcohol dehydrogenase metabolizes it -microsomal ethanol oxidizing system (MEOS) --reactive oxygen species produces
short chain fatty acids
-range from 4-7 carbons in length -remain liquid at colder temp
medium chain fatty acids
-range from 8-12 carbons -solidify in the refrigerator but liquefy at room temp
major health behaviours that reduce the risk of cardiovascular disease
-reduced dietary cholesterol intake -reduced saturated fat -plant sterols: 1-2g daily -diets that include soy protein, soluble fibre, and/or nuts -dietary patterns such as the mediterranean type diet, DASH diet, and the portfolio diet -moderated alcohol intake -weight loss and reduction of abdominal obesity -EPA & DHA: 2-4 g daily -exercise -smoking cessation
eicosanoids
-regulatory molecules including prostaglandins and related compounds -made from omega-6 and omega-3 -regulate blood clotting, BP, immune function, and other body process -eicosanoids derived from omega-3 FA, such as EPA have anti-inflammatory properties -eicosanoids derived from omega-6 FA, such as arachidonic acid, promote inflammation
dietary lipids that protect against heart disease
-replacing saturated and trans fats with dietary omega-6 and omega-3 polyunsaturated fatty acids as well as monounsaturated fatty acids tends to decrease the risk of HD. -some of this is due to a reduction in LDL cholesterol and an increase in HDL cholesterol
what happens if the amount of LDL cholesterol in the blood exceeds the amount that can be taken up by cells?
-results in a high level of LDL cholesterol -high levels of LDL particles in the blood have been associated with an increased risk for heart disease
age effects on heart disease
-risk of developing heart disease increases with age -men generally affected a decade earlier than women -this is partially due to the protective effect the hormone estrogen has n women -the effects of menopause (decline of estrogen and weight gain) increase risk of HD
replacing saturated and trans fats in the diet
-saturated and trans fats are best replace with unsaturated fats -replacing saturated and trans fats with refined carbs and sugars does not decrease risk of HD, it remains roughly the same -replacing with unrefined carbs and low GI foods is likely to be beneficial
how do macrophages and foam cells continue the inflammatory response?
-secrete growth factors and other chemicals -the release of growth factors signals smooth-muscle cells from the wall of the artery to migrate into the fatty streak and secrete fibrous proteins -platelets become sticky and clump together around the lesion -as the lesion enlarges, it causes the artery to narrow and lose its elasticity, hampering blood flow -a fibrous cap of smooth muscle cells and fibrous proteins forms over the mixture of WBCs, lipids, and debris, walling it off from the lumen of the artery
effect ethnicity has on heart disease risk
-studies suggest that canadians of south again origin have higher risk of HD than europeans -europeans have higher risk than chinese -first nations have higher risk than european origin
conjugated linoleic acid (CLA)
-trans fats that occur naturally in beef and dairy products differ in composition from hydrogenated fats and include conjugated linoleic acid (CLA) which is different from the essential fatty acid linoleic acid
lipid bilayer
-two layers of phosphoglyceride molecules oriented so that the fat-soluble fatty acid tails are sandwiched between the water-soluble phosphate-containing heads -this for the barrier that helps regulate which substances can pass into and out of the cell
atherosclerosis
-type of cardiovascular disease that involves the buildup of fatty material in the artery walls, reducing their elasticity and eventually blocking the flow of blood
phospholipids
-types of lipids containing phosphorous -most common are the phosphoglycerides, which are composed of a glycerol backbone with two fatty acids and a phosphate group attached
sterols
-types of lipids with a structure composed of multiple chemical rings -do not dissolve well in water -found in both plants and animals
melting points in saturated vs unsaturated fatty acids
-unsaturated fatty acids melt at cooler temperatures than saturated fatty acids of the same chain length -the more unsaturated bonds a fatty acid contains, the more likely it is to be liquid at room temp
role of cholesterol in synthesis of regulatory molecules
-used to make number of hormones -- include sec hormones estrogen and cholesterol along with the stress hormone cortisol
dietary sources of alpha-linolenic acid
-walnuts -flaxseed -leafy greens -canola oil
factors affect blood alcohol level
-weight -gender -food -drinking rate -type of drink
role of insulin in carbohydrate metabolism
-when blood-glucose levels are high, insultin stimulates uptake of glucose by the liver and its conversion to the storage polysaccharide, glycogen -insulin also stimulates activity of the enzyme lipoprotein lipase, which promotes the uptakes of triglycerides from chylomicrons -insulin suppresses activity of hormone-sensitive lipase, which in turn suppresses the release of free fatty acids from adipose tissue into the blood
in what age group was consuming above 35% of kcal from fat most common?
25-50 year age group for both men and women
% of cancers directly linked to dietary and lifestyle choices
30-40%
% of canadian diet that comes from fat
31%
% of adults with high blood cholesterol levels
40%
after a meal, where are lipids transported?
from small intestine to the organs in the body for use as fuel
lipoprotein lipase
an enzyme that breaks down triglycerides into fatty acids and glycerol; attached to the cells membranes of cells that line the blood vessels
antioxidants and HD
decrease the oxidation of LDL cholesterol and are hypothesized to prevent development of plaque in artery walls
saturated fat and heart disease
diet high in saturated fat increase LDL cholesterol which then increases risk of atherosclerosis, increases risk of HD
what happens if blood clots form in the blood vessels that supply the heart muscle? brain?
heart: blood flow to the heart muscle is interrupted and eat cells die, resulting in a heart attack or myocardial infarction brain: blood flow to the brain interrupted results in stroke
why is the ratio of omega-3 to omega-6 fatty acids in the diet important?
it is important for process such as blood pressure regulation, blood clotting, and immune function since the ratio of omega-3 to omega-6 fatty acids determined the biological effect of the molecule synthesized
calculating % energy from fat
kcal from fat/total kcal x 100%
"cholesterol-free" labelling rules
label is only permitted for foods that contain less than 2mg of cholesterol and 2g or less of saturated and trans fat per serving
daily recommended trans fat
less than 1% of energy or 2g/day
how to reduce the intake of saturated fatty acids
limit: -fried foods -high fat snack foods -bakery products -high fat processed foods -high fat meats and dairy
most common polyunsaturated fatty acid
linoleic acid (omega-6) -- found in corn, safflower, soybean oils
very low density lipoproteins (VLDLs)
lipoproteins assembled by the liver that carry lipids from the liver and deliver triglycerides to body cells
chylomicrons
lipoproteins that transport lipids from the mucosal cells of the small intestine and deliver triglycerides to other body cells
what are omega-3 and omega-6 fatty acids used for?
synthesize regulatory molecules in the body and the biological effect of the molecule synthesize depends on the structure of the fatty acid from which it is made
what does the function of a phosphoglyceride depend on?
the molecule that is attached to the phosphate group
glucose/fatty acid cycle
the relationship between blood glucose and free Fas. When blood glucose levels are high, as in the post-prandial state, free FA levels are low. in the fasting state, when blood glucose levels decline, free FA levels increase
what happens when less energy is consumed than is needed?
the release of these (free) fatty acids is especially stimulated -the enzyme hormone-sensitive lipase inside the fat cells receives a hormonal signal enhancing enzyme activity, promoting breakdown of stored triglycerides -the free FAs and glycerol are released directly into blood, where they can be taken up by cells throughout the body to produce ATP
post-prandial state
the time following a meal when nutrients from the meal are being absorbed
what happens when saturated fatty acids in the diet are replaced with polyunsaturated fatty acids?
this has been associated with a reduced risk of cardiovascular disease
