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70 Cards in this Set
- Front
- Back
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Properties of Lipids |
1. Do not dissolve in water 2. Energy dense (9 kcal/g) 3. Fats which are solid at room termperature 4. Oils which are liquid at room temperature 5. Made of triglycerides, phospholipds, sterols. |
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Triglycerides (structure) |
Main form of lipids in food and body (storage) glycerol with 3 fatty acids attached Glycerol has 3 hydroxyl groups (-OH) fatty acids are long hydrogen carbon chains with a carboxyl end, and methyl end fatty acids are attached to the hydroxyl groups on glycerol |
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Esterfication |
joining of 3 fatty acids to glycerol |
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De-esterfication |
release of fatty acids from glycerol resulting in free fatty acids |
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Re-esterfication |
reattaching the fatty acid to glycerol |
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monoglyceride |
1 fatty acid + glycerol (loss of two fatty acids) |
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Long chain fatty acids (LCFA) |
12 or more carbons animal fat, plant longest to digest transported via lymphatic system (not portal) |
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Medium chain fatty acids |
6-11 carbons coconut oil, palm oil transported via portal system |
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Short chain fatty acids |
less than 6 carbons dairy transported via portal system |
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Saturated fatty acids (SFA) |
every carbon has 4 bonds no double bonds resist spoilage stearic acid, most common, found in animal fat palm and coconut oil, largely saturated |
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Monounsaturated fatty acids (MUFA) |
2 H missing one double bond formed between carbons oleic acid, part of olive oil, and canola oils |
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Polyunsaturated fatty acids (PUFA) |
2 or more double bonds Linoleic (Omega-6) acid found in safflower, corn, and soybean oil |
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Trans fatty acid |
If hydrogens are found attached to double bonded carbons on opposite sides straight carbon chains with zigzag |
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Cis |
Unsaturated hydrogens attached to same side as double bonded carbons bent |
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Who creates trans fat? |
Food manufactures create trans fat by process of hydrogenation |
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What is hydrogenation? |
Hydrogen ions are added, which breaks the carbon double bonds of unsaturated fats, allowing the carbons to accept the hydrogens makes fat more like saturated fat |
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What are the benefits of hydrogenation? |
The lipid becomes more stable, solid |
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Food sources of trans/hydrogenation |
margine, vegetable shortening either hydrogenated, or partially hydrogenated |
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What is current intake of trans fatty acids? |
about 3% |
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Health dangers of excessive trans fatty acids |
Increase risk for heart disease raises LDL lowers HDL increases inflammation FDA now requires on food labels |
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4 ways to minimize trans fatty acid intake |
limit use of hydrogenated fats limit deep-fried foods limit high fat baked goods limit non-dairy creamer observe food labels |
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Naming fatty acids Omega system |
double bond closest to omega (methyl) end Linoeic acid 18:2n6 18 carbons 2 double bonds 1st double bond starts at 6th carbon |
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Naming fatty acids delta system |
describes fatty acids in relation to carboxyl end of carbon chain indicates location of all double bonds written 18:2 delta 9, 12 |
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Essential fatty acids |
body can make all PUFA except for 2: Omega-3 fatty acids - alpha-linolenic acid Omega-6 fatty acids - linoleic acid
must be ingested, our bodies cannot make fatty acid before 9th carbon |
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Omega-3 (alpha linoleic fatty acid |
If first double bond between 3rd and 4th carbon from methyl end, called omega 3 fatty acid example alpha-linolenic
Found in fish canola oil soybean oil walnuts flax seeds
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Omega-6 (Linoleic acid) |
If first double bond is between the 6th and 7th carbon from methyl end, called omega-6
Found in: safflower oil corn oil soybean oil |
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Omega 3 and Omega 6 FA processed into other fatty acids |
Omega 3- eicosapentaeonic acid (EPA docosahexanenoic acid (DHA)
Omega 6-Dihomo-gamma-linolenic acid arachidonic acid
then all converted to eicosanoids |
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Eicosanoids |
Eicosanoids are hormone like compounds in the body such as prostoglandins, prostacyclins, thromboxanes, etc
Omega-6 eicosanoids increase blood clotting, and increase inflammatory response
Omega-3 eicosanoids decresse blood clotting, reduce heart attack, excess may cause hemorrhagic stroke |
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Fat replacements |
water protein carbohydrates-starch derivatives, fiber, and gums Engineered fats: olestra, salatrim |
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5 functions of triglycerides |
provide energy provide compact energy source insulate, protect body aid fat soluble vitamin absorption and transport essential fatty acid functions |
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Phospholipid structure |
nearly same as triglyceride but:
built on glycerol backbone
has at least one fatty acid replaced with a phosphorus containing compound
allows this lipid type to be in water!
phosphate (head) of phosphoslipid is hydrophillic (water loving)
fatty acid end (tail) is hydrophobic (water fearing) |
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Phospholipids source? |
synthesized by body (liver)
Food: egg yolks wheat germ peanuts
food sources not essential, liver produces enough |
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Phospholipids Functions |
component of cell membranes
emulsifier- forms shell around fat droplets and allows them to mix with water
bile acids |
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Leithin |
part of eggs (lecithin in yoke) and soybeans used as food additive, keeping water and oil mixed
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Sterols structure |
Ring structure, most known is cholesterol |
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Sterols Functions |
Essential component of cell membrane produce by liver found only in animal products precursor to bile acids |
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Cholesterol forms what three important hormones? |
Estrogen
testosterone
vitamin D |
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Recommendations for fat intake |
no RDA value
Institute of Medicine (IOM) and American Dietetic Association recommends: AMDR limit total fat intake to 20%-35% of total energy intake
over 35% implies saturated fat values are too high
under 20% implies not enough vitamin A,E (which is fat soluble) |
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Institute of medicine (IOM) recommended daily fate intakes
Total Dietary fat saturated fat trans fat unsaturated fat omega 6 linoleic acid omega 3 alpha linolenic acid cholesterol |
Total dietary fat 20-35% of calories
Saturated fat as low as possible Trans fat as low as possible unsaturated fat most of fat intake omega-6 linoleic acid 5% of calories omega 3 alpha-linolenic acid .6-1.25% of calories
Cholestoral as low as possilbe no more then 200-300 mg
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American Heart association Recommendations
saturated polyunsaturated trans cholesterol |
Limit saturated fats 10% of total calories
Limit polyunsaturated fats to 0% of total calories
Minimize trans fat intake
Limit cholesterol intake less than 300 mg daily
values decrease for "at risk" populations |
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Essential fatty acid needs |
adequate intake -4 tablespoons daily
deficiency unlikely
toxicity no upper level set
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Fat digestion
% absorbed
mouth enzyme
stomach enzyme |
95% of fat consumed is absorbed
mouth lingual lipase - only short fatty acid chains
Stomach gastric lipase - acts on triglycerides containg long and mdedium chain fatty acidz |
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Fat Digestion Small Intestine
CCK
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Small Intestine
CCK stimulates pancreas to release:
pancreatic lipase pancreatic colipase-help facilitate lipase enzyme action CCK stimulates release of bile to help emulsify fat, forms micelles Fat broken down into monglycerides fatty acids |
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Fat Digestion
What are triglycerides broken down into? Phospholipids? Cholesterol esters? |
Triglycerides to monoglycerides and free fatty acids
Phospholipids to: free fatty acids glycerol phosphoric acid
cholesterol esters to cholesterol and free fatty acids |
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Fat Absorption
Large fatty acids
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Large fatty acids (greater than 12 carbons): requires bile, which emulsifies large fatty acid forming structure called micelle
Micelles are readily absorbed into cells of small intestine at brush border |
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Fat absorption small intestine short and medium chain fatty acids |
Small and medium sized fatty acids (less than 6 carbons, or 6-11 carbons, respectively) absorb directly into the cell of the small intestine. |
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Fat absorption SI short, medium (circulation
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Short and medium chain fatty acids absorbed via portal vein and enter into cardiovascular system directly |
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fat absorption Long chain fatty acid (cardiovascular) |
Long chain fatty acids are re-esterified as triglycerides ad chylomicrons and enter the lymphatic system dumped into cardiovascular system at the thoracic duct near the heart
Bile recycled enteroheptic circulation |
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Absorption of triglycerides |
1. Large fat droplets enter small intestine 2. Bile (mostly) lecithin emulsify fats into smaller particles 3. Lipase breaks down fat into fatty acids and monoglycerides 4. Monoglycerides and fatty acids absorbed as micelles through the brush border and re-formed into triglycerides 5. short and medium chain fatty acids enter CV via portal vein 6. Triglycerides combine with: cholesterol protein phospholipids to form chylomicrons, which enter the lymphatic system |
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Transport of Dietary fats |
1. absorbed micelles and large fatty acids reformed into triglycerdes with in intestinal cells
2. most lipid components repackaged into chylomicrons- type of lipoprotein that only comes from intestinal cells. |
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Chylomicrons enter lymphatic circulation... to .. |
Chylomicrons enter lymphatic circulation to reach blood stream at thoracic duct
So many lipids from diet are transported in lymph, through blood to liver as chylomicrons. |
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Cholesterol Uptake, Receptor Pathway |
1. LDL broken down and utilized in body. 2. Receptors on cell surface (mostly liver) bind to LDL surface 3. LDL taken up by endocytosis 4. LDL broken down to free cholesterol, protein |
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How is the (LDL) receptor pathway enhanced? |
Enhanced by diets low in cholesterol and saturated fat
excess oxidized by free radicals, antioxidants. |
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Transport of dietary fats
What does lipoprotein lipase do? |
lipoprotein lipase on blood vessel walls break down triglycerides in the chylomicrons into fatty acids and glycerol
fatty acids absorbed by cells or stored in adipose
2-10 hours to clear chylomicrons. |
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Transporting Fat
What is fat from liver transported as?
components? |
fat from liver transported as lipoproteins.
Lipid core components: proteins carbohydrates free fatty acids
Shell components: protein, phospholipids, cholesterol, triglycerides |
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Transport of Synthesized Fats
liver packages cholesterol, triglycerides as?
LPL? |
Liver packages cholesterol and triglycerides as VLDL (very low density lipoprotein)
Lipoprotein lipase takes triglycerides form VLDL and moves into cells.
As lipids lost, the VLDL becomes more dense LDL. main component to cholesterol. |
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Receptor pathway cholesterol uptake
Cholesterol from LDL taken by receptor |
Cholesterol from LDL is taken by a receptor called B 100
Cholesterol used in cell manufacture many compounds (mainly hormones)
when B100 receptor no longer takes LDL, LDL is increased in blood and becomes oxidized (damaged) by free radicals
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Scavenger pathway for cholesterol |
1. removes oxidized LDL 2. Scavenger WBC removes oxidized LDL from circulation. 3. prevents oxidized LDL from returning to circulation. |
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Scavenger pathway uptake cholesterol diet enhancements |
Process enhanced by diets: high in cholesterol saturated fat trans fat
cholesterol builds up on blood vessel walls (plaque) |
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atherosclerosis |
plaque build up in blood vessel from cholesterol blockage |
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HDL
where is HDL synthesized?
Functions |
HDL (high density lipoprotein) "good cholesterol"
Synthesized by liver and intestine HDL high proportion of protein
Functions:
Pick up cholesterol from dying cells and other sources Transfers cholesterol to other lipoproteins for transport to liver for excretion. HDL can also transfer directly back to liver Blocks oxidation of LDL |
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Benefits of a high HDL level |
1. Remove cholesterol from bloodstream. 2. HDL may block oxidation of LDL. 3. Reduce risk of heart disease 4. Pre-menopausal women have higher HDL. 5. HDL level is indication of CV health. |
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Health Concerns
High PUSF
Excessive omega 3
imbalances in omega 3 an omega 6 fats |
1. High polyunsaturated fat intake (greater than 10%) increases cholesterol deposits in artieries and may block immune system
2. Excessive omega 3 fat intake more than 8 oz of source daily may impair immune system, cause excessive bleeding
3. Imbalances in omega 3 and omega 6 fats
Cause inflammation |
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Health Concerns
rancid fats
trans fats
total fat |
1. Intake of rancid fats contain components that damage cells (reason for hydrogenation)
2. Diets high in trans fats: raise LDL, lower HDL, Increase Inflammation, FDA require on food label
3. Diets high in total fat: risks of obesity, certain cancers, and CV disease |
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Cardiovascular Disease (CVD)
Development Result Risk factors |
1. Development of CVD: Atherosclerotic plaque
2. Result: heart attack, stroke
3. Risk factors: Cannot change: age, race, gender, genetics
Can change: triglyceride and cholesterol levels, hypertension, smoking, physical inactivity, obesity, diabetes, and other diseases |
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Ratings of blood lipoprotein levels mg/dl
Cholesterol (desirable, borderline high, high) |
Total cholesterol
less than 200 desirable 200-239 borderline high 240 or more high |
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LDL cholesterol |
less than 100 optimal 100-129 near optimal 130-159 borderline high 160-189 high 190 or more very high |
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HDL cholesterol |
less then 30 low 50 or more high |
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Triglycerides |
less than 100 optimal 100-149 near optimal 150-199 borderline high 200-499 high more than 500 very high |
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Preventing CVD
Fat intake values Total fat Sat. fat Trans PUSF MUSF Cholesterol
Include 2g sterols soluble fiber body weight increase physical activity |
Total fat 20-35% total calories Saturated fat less than 7% total calores Trans fat low PUSF less than 10% MUSF less than 20% Cholesterol less than 200 mg Include 2 g plant stanols/sterols Soluble fiber 20-30g Body weight healthy level Increase physical fitness |
