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93 Cards in this Set
- Front
- Back
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Lipids in foods
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Foods richest in fat are veg oil, margarine, butter, avocado and nuts
Many prot rich foods, such as meat, cheese, and peanut butter are high in fat Dietary fats provide flavor, texture, and energy, but also vit A, D, E and K Contribute to feeling full and satisfied and help us lengthen the time between meals |
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Properties of lipids
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Do not readily dissolve in water (transport, removal)
Fats - solid at room temp (TAG mostly of SFA) Oils - liquid at room temp ( TAG mostly of UFA) TAG are main form of lipids in food and body (storage) Energy dense - 9 cal/g |
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Functions of lipids
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Fatty acids
Triacylglycerols Phospholipids Cholesterol (sterols) |
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Fatty Acids
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Largest source of energy (TAG)
Precursors of eicosanoids (PL) |
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Triacylglycerols
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Provide energy (FA)
Store energy (stable and dry) Transport of lipid-soluble nutrients |
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Phospholipids
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Most common lipids in BM (biological membranes) (GPL)
Digestion of dietary lipids (lecithin) Sources of eicosanoids (UFA at C2) Transport of lipid-soluble nutrients |
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Cholesterol
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Sources of all steroid hormones and BS (bile salts) for lipid digestion
Component of BM Transfer of lipid-soluble nutrients Source of vit D |
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Fatty Acids
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Simplest lipids
R-COOH Short, med, long chains SFA UFA - MUFA, PUFA Trans (TFA) - mostly man-made Nonessential (NEFA) Essential (EFA) - Linoleate / linoleic acid / C18:2 / w-6, Linolenate / linolenic acid / C18:3 / w-3 We store mostly long chain Generally same energy whether sat or unsat, length determines storage |
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FA chain and melting point
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Long Chain FA - >or=12 C, SFA solid at room temp, UFA liquid at room temp, most abundant in cells (C16:0 palmitate, C18:0 stearate, C18:1 oleate)
Medium Chain FA - 6-10 C, semi-liquid at room temp (8-10 gel-like) short Chain FA - <6C, liquid at room temp |
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Trans FA
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We make cis
Improper storage and sometimes cooking (preparation) causes = causes bending in cis In trans no bending even with = so lowers fluidity of membrane |
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Cis and Trans
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Cis FA are more common in foods than trans FA
Trans fats are primarily found in foods containing hydrogenated fats, such as margarine, shortening and deep fat-fried foods |
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Hydrogenation of PUFA
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Changes comp9osition and texture
Eliminates = "Makes food more fxl" - last longer for food industry |
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Trans fat and food labels
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Hydrogenated fats appear in ingredients list as partially hydrogenated or hydrogenated fat
Can call "trans fat free" is .5g or less/serving |
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Hydrogenation of UFA
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Process used to solidify vegetable oils (increase food functionality)
Addition of H to C=C double bonds To increase shelf-life of foods (prevent or slow down rancidity) Formation of trans fatty acids |
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Rancidity
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Oxidized vegetable UFA
Breakdown of the C=C double bonds by ultraviolet rays, oxidants, O2 Yields unpleasant odor, flavor, sickness when consumed PUFA more susceptible (more =) Limits shelf life |
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Prevention of rancidity
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Vacuum-packed (elim O2)
Hydrogenation (elim = ) Addition of natural antioxidants - Vit E (tocopherols, tocotrienols) and Vit C Addition of artificial antioxidants - butylated hydroxyanisol (BHA), butylated hydroxytoluene (BHT) |
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Essential FA
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Made by plants only
Body can only make = no further than C 9 and 10 from carboxy end Most foods have higher levels of C18:2 (w-6) than C18:3 (w-3) Metabolized to make eicosaniods (prostaglandins, thromboxanes, leukotrienes) |
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Omega-6 fa
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Linoleic acid -> dihomo-gamma-linolenic acid -> arachidonic acid -> eicosanoids
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Omega-3 fa
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Alphaic acid -> eisosapentoenic acid (EPA) -> docosahexaenoic acid (DHA) -> eicosanoids
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Metabolism of EFA
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If not good levels of omega-3, make eicosanoids that cause inflammation
If good amounts, make eicosanoids that fight inflammation |
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Omega-3 fatty acids
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a-linolenic acid (ALA, C18:3) found in fish, canola oil, soybean oil, walnus, flax seeds
Eicosapenaenoic acid (EPA, C20:5) and docosahexaenoic acid (DHA, C22:6) are related fatty acids (high in fish oils-esp cold water fish, NEVER found in plant foods) |
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w-3 fatty acids in fish
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2.0 is recommended
Atlantic salmon - 1.8 Anchovy - 1.7 Sardines - 1.4 Tuna, white, canned - .7 Halibut - .4 Catfish, channel - .2 |
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Omega-6 fatty acids
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Linoleic acid (LA, C18:2) found in many foods, particularly plant oils
Lead to production of arachidonic acid (AA, C20:4), the precursor of most eicosanoids Excess intake may cause general inflammation and increase BP |
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Wild Salmon
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Total FA - 6.3
SFA - .98 MUFA - 2.1 PUFA - 2.54 LA - .17 AA - .27 ALA - .3 EPA - .32 DHA - 1.12 w-6 - .44 w-3 - 1.74 About 1:4 |
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Farmed Salmon
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Total FA - 10.8
SFA - 2.18 MUFA - 3.87 PUFA - 3.94 LA - .59 AA - 1.15 ALA - .09 EPA - .62 DHA - 1.29 w-6 - 1.74 w-3 - 2.00 About 1:1 |
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Eicosanoids
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Group of hormone-like compounds
Regulates BP, childbirth, clotting, immune responses, inflammatory responses, and stomach secretions Bypass the blood stream and work in the area or origin |
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Food sources of Triglycerides
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Most foods provide at least some TG
Most abundant lipids in food and body Some foods are primarily TG (animal fats and veg oils) Bakery items have significant levels of TG (snack foods and dairy desserts) Plant foods are generally low in TG (except for veg oils, nuts, and avocados) TG found in plant foods are generally made of UFA (except for coconut and palm oils) |
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SFA
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Increase blood levels of cho
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SFA
long chain |
0=
Lard, fat in beef, pork, and lamb Solid at room temp |
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SFA
medium and short chain |
0=
Milk fat (butter), coconut oil, palm oil, palm kernel oil Soft or liquid at room temp |
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MUFA
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Decrease blood levels of cho
1= Olive oil, canola oil, peanut oil Liquid at room temp |
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PUFA
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Decrease blood levels of cho
2 or more= Sunflower oil, corn oil, safflower oil, fish oil Liquid at room temp |
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EFA
Omega-3: alpha linolenic acid |
Reduces inflammation responses, blood clotting, and plasma TG
3= Cold water fish (salmon, tuna, sardines, mackerel), walnuts, flaxseed, hemp oil, canola oil, soybean oil Liquid at room temp |
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EFA
Omega-6: linoleic acid |
Regulates BP and increases blood clotting
2= Beef, poultry, safflower oil, sunflower oil, corn oil Solid to liquid at room temp |
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TFA
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Increases blood cho more than SFA
Less than the PUFA used to make trans fat Margarine (squeeze, tub, stick), shortening Soft to very solid at room temp |
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Flax seeds
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Seeds high in omega-3 fats
Can be ground and used as a meal in baked goods Can be pressed to extract the oil, which is sold as a nutritional supplement Only have one type of omega-3 fa, linolenate C18:3 (ALA) |
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Is fish safe to eat?
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Potential toxic contaminants - pesticides, herbicides, methylmercury
To minimize risks - choose wild versus farmedn shoose small non-predatory fish, vary type of fish, buy it from reputable markets, discard fatty portions from fish, check the locations where you catch own fish |
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Types of FA in fats and oils
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SFA - coconut oil, butter, palm oil, lard or beef fat
MUFA - olive oil, canola oil, peanut oil PUFA - safflower oil, sunflower oil, corn oil, soybean oil TFA - tub margarine, stick margarin, shortening |
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Fat replacements
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Dairy-Lo - fat replaced by water and protein
A-Trim, Maltrin, Stellar, Oatrim, and gum fibers - starch derivatives Olestra (Olean) and salatrim (Benefat) - engineered fats (fatsand sucrose), cannot be digested or absorbed |
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Reduced fat ice cream
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A reduced fat food many not be lower in cal than its full fat counterpart
When fat is removed, something must be added (usually sugars) Fat replacements, such as gum fiber,are often used in soft serve ice cream |
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Functions of TG
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Provide energy - high energy density, 9 cal/g - energy for all cells except brain and RBC
Efficient storage of energy (stored dry) - adipocytes are 80% TG and 20% water-soluble Insulation and protection of organs - visceral fat covers and protects internal organs Transport fat-soluble nutrients - components of lipoproteins Satiety, flavor and mouth feel - kees us full longer |
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Energy
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When at rest or during light activity, the body uses mostly fa for fuel
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Functions of EFA
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Help in keeping membranes fluid
DHA is needed during fetal life and infancy for normal retina development and function DHA is also vital in the first weeks of embryonic life for normal CNS development and maturation A generous intake of w-3 FA (ALA, EPA, and DHA) reduces CVD by reducing general inflammation and BP |
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Signs and symptoms of EFA deficiency
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Flaky, ithcy skin
Diarrhea Infections Retarded growth and wound healing Anemia |
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Phospholipids
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Many types of PL are found in food and in the body cell membranes, particularly in brain cells
PL are amphipathic Two major fxn - cell membrane component, emulsifier |
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Fxn of PL in foods
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PL, other lipids and other molecues are often used as emulsifiers in food preparation and manufacturing
Eggs are used in many baking recipes Food makers add emulsifiers to keep the fat and the watery compounds in them from separating Without emulsifiers, foods that contain fatty and watery compounds would seem oily and would have a sandy or rough texture |
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Common emulsifiers
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Added to food to improve texture
Lecithins Monoglycerides Diglycerides Polysorbate 60,80 (not natural) Egg whites and yolks Whole eggs |
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Natural sources of PL
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Make by body or found in diet
Egg yolks, wheat germ and nuts are high in lecithins Lecithin supplements have been promoted as a way to lose weight, lower cho, and reduce risk of Alzheimer's disease (data on cho and Alzheimer's is not conclusive and no effect on weight loss found) |
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Sterols
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Cho is the main sterol
Polar (amphipathic) lipid Functions of cho - cell membranes, body steroid hormones, vit D, bile salts, emulsifier, lipoprotein component |
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Sources of cho
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Found in foods of animal origin
Most people get about 1/3 of their cho from foods and the rest is made by the body On ave, American diets supplied about 180 -325 mg of cho daily Plants make other sterols, such as ergosterol (vit D precursor) and sitostanol (sitosterol), which is added to some margarines - can potentially lower the absorption of diet cho |
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Cho in foods
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3oz beef brains - 2635 mg
3oz beef liver - 337 mg 1 large egg - 209 mg 1 cup 1% mild - 12 mg 1 cup fat-free milk - 5 mg 1 large egg white - 0 |
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Recommended lipid intakes
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There is no RDA for fat but there is an AI for children
IOM's AMDR for fat is 20-35% cal - >35% often means too much sat fat, <20% increases chance of too little vit E and EFA IOM recommends that sat fat intake, including trans fat and cho levels be kept as low as possible |
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Recommended lipid intakes
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Healthy People 2010 - Reduce % of people over 2 yo who get more than 10% of cal from sat fat
AHA and Diet Guidelines for Americans - healthy people limit sat fat and PUFA cal to no more than 10% each and minimize trans fat intake More - When fat cal is >30%, MUFA supply the extra cal and cho should be limited to about 300 mg daily |
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Recommended lipid intakes
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For people at risk of heart disease - 20% of total fat cal, 7% of sat fat cal, 200 mg or less of cho, less than 20% of total fat cal diets need the supervision of a doc
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Recommended lipid intakes
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Total dietary fat - 20-35% of cal
Sat fat - low as poss Trans fat - low as poss Unsat fat - most of fat intake Omega 6 - 5% of cal Omega 3 - .6-1.2% of cal Cho - low as poss |
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Mediterranean diet
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Up to 40% of cal from fat can be healthy if MUFA account for most of fat
Features - olive oil is main fat, rich daily intake of fruits whole grains beans veggies (leafy greans) nuts and seeds, reduced intake of processed foods and increased intake of seasonally fresh and locally grown foods, daily intake of small amounts of cheese and yogurt, weekly intake of low to moderate amounts of fish, limited use of eggs and red meat, regular exercise, moderate drinking of wine at meals |
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EFA needs
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IOM set AI for EFA - 120 EFA cal for women (13g - 12g w-6 and 1g w-3), 170 total EFA cal for men (19g - 17g w-6 and 2g w-3)
No UL for EFA - Greenland's Eskimos safely consume 6.5g of w-3 (3-5 times higher than AI) |
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Our fat intake
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We get plenty of fat
Ave 33% of cal from fat During last century fat intake has doubled Omega-6 fat intake is plentiful but omega-3 is lower than optimal - at least 2 servings of cold water fish/week, walnuts flaxseeds and canols soybean and flaxseed oils, Recommend fish supplements with 650mg of EPA and 650mg of DHA (pts with bleeding disorders, scheduled surgeries, under anticoagulants should check with doc to minimize risk of harmful side effects with omega-3 supp which can prolong bleeding time) |
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Digestion of dietary lipids
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Mouth - lipase secreted, little or no fat digested
Stomach - lipase secreted, little fat digested Liver - produces bile (released and stored by GB into CBD which empties into SI ), bile emulsifies fat Pancreas - secretes lipase (digests TG), phospholipase (digests phospholipids), and cho esterase (digests cho) into CBD which empties into SI SI - fat is digested and absorbed in duodenum and jejunum, bile is reabsorbed in ileum LI - less than 5% of fat passes through and is excreted |
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Digestion of dietary lipids
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Pancreatic lipase (and lipase) - TAG - 2FA + 2MAG
Remove FA at 1 and 3 That is 90% Phospholipase A - Phospholipids - FA + Lyso-PL Remove FA at 2 Cholesterol ester hydrolase - Cholesteryl esters - FA + CHO Those 2 are 10% |
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4 products of lipid digestion
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FA
MAG Lyso PL Free CHO |
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Dietary lipid absorption
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Large fat droplets enter SI after meal
Bile and lecithin emulsify into smaller particles Lipase breaks down fat into FA and monoglycerides Monoclycerides and FA are absorbed as micelles through the brush border and then re-formed into TG Short and medium chain FA enter the blood stream TG combine with cho, prot, and PL to form chylomicrons, which enter the lymphatic system |
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Transport of dietary lipids
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Dietary lipids are reassembled
Packaged into chylomicrons (LP) LP components (TAG, PL, CNO/CHOE, apoproteins Lipoprotein lipase breaks down TAG into chylomicrons and VLDL FA and glycerol are absorbed by cells Chylomcrons enter lymphatic circulation to reach bloodstream at thoracic duct Takes up to 10-12 hrs to clear chylomicrons from blood |
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Functions of apoproteins
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Increase solubility of lipoproteins
ApoC-II - activates lipoprotein lipase ApoC-III - inhibits lipoprotein lipase ApoB-100 - binds to LDL receptor ApoE - triggers clearance of VLDL and chylomicron remnants (a varient mutation, like in Italy, lowers risk of CVD) |
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Chylomicron
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TG
Carries dietary fat from the SI to cells |
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VLDL
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TG
Carries lipids both taken up and make by the liver to cells |
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LDL
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Cho
Carries cho made by liver and from other sources to cells |
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HDL
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Prot
Helps remove cho from cells and in turn excretion of cho from the body |
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Lipoproteins
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Chylomicron - 80-90% TG
VLDL - 55-65% TG LDL - 45% CHO HDL - 45-50% Prot |
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Lipoprotein metabolism
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see chart
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Receptor Pathway
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Receptors on cell surface (mostly liver) bind to LDL
LDL taken up by endocytosis Apoproteins make it possible to bind Process enhanced by diets low in cho and sat fat |
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HDL
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Hynthesized by liver and intestine
High proportion of prot Functions - picks up cho from dying cells and blood, transfers cho to other lipoproteins for transport to liver for excretion, can transfer directly back to liver, blocks axidation of LDL, can closely predict he risk of CVD |
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Antioxidants
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Reduce oxidation (LDL)
Slow down LDL uptake into scavenger cells Need for supplements? disappointing results Plant food up! - Ascorbate, vit E, lycopene, carotenoids, resveratrol, sulforaphane, anthocyanins |
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Scavenger Pathway
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Scavenger WBC removes (oxidized) LDL from circulaton
Prevents oxidized LDL from returning to circulation Build-up of plaque on walls of blood vessels leads to atherosclerosis Process enhanced by diets high in cho, sat fat, and trans fat |
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Blood lipids
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Reducing the intake of fried foods can help lower blood lipid levels
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High PUFA intake
>10% cal |
Increases amount of arteries hurt by cho and CVD
Impair immune system |
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Excessive omega-3 intake
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Impair immune system
Uncontrolled bleeding and hemorrhagic stroke |
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Imbalances in omega-3 and omega-6 fats
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Too little w-3 causes general inflammation
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Intake of rancid fats
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Organic peroxides and aldehydes can damage cells
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Diets high in trans fats
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Increases total cho and lowers HDL levels which increases risk of CVD
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Diets high in total fat
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Increases risk of obesity
Increases risk of colon-rectum, prostate, and breast cancer |
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CVD
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Leading cause of death in NA
500,00 people each year (60% >cancer 1.5 mill people in USA each year has heart attack Male to Female is 2:1 Women lag about 10 yrs behind men in developing disease Kills more women than any other disease For each death from CVD, 20 more have symptoms High fat diets increase risk Symptoms develop over years and become obvious on old age |
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Plaque formation
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CVD begins with formation of plaques on blood vessel walls
Contributors - smoking, diabetes, HT, homocysteine, LDL, Blood vessel inflammation, excess iron and copper |
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Risk factors for CVD
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HIgh fat diets
Age - over 83% who die >=65 Gender - men greater risk and have attacks earlier Genetics - have close reletive who died young (<50) Race - Aftican, Hispanic, Native and Asian AMericans are at higher risk because higher obesity and diabetes in these groups |
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Risk factors for CVD
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CHO levels
TG levels HT Smoking Physical inactivity Obesity Diabetes Liver and kidney disease Low thyroid hormone levels |
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Lipid profile
Total CHO |
Desirable - <200mg
Borderline high - 200-239 High - >=240 |
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Lipid profile
LDL |
Optimal - <100
Near optimal - 100-129 Borderline high - 130-159 High - 160-189 Very high - >=190 |
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Lipid profile
HDL |
Low - <30
High - >=50 |
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Lipid profile
TG |
Optimal - <100
Near optimal - 100-149 Borderline high - 150-199 High - 200-499 Very high >=500 |
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Preventing CVD
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Total fat intake 20-35% of total cal
SFA intake below 7% of total cal TFA intake low PUFA intake below 10% total cal MUFA intake below 20% total cal CHO intake below 200 mg/day Include 2g of plant stanols/day Increase soluble fiber to 20-30g/day Keep healthy body weight Increase physical activity |
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Signs of Heart Attack
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Men and women - intense, prolonged chest pain, shortness of breath, sweating, weakness, irregular heartbeat
Women - Nausea and vomiting, dizziness, jaw, neck, and shoulder pain |
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Signs of stroke
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Sudden!
Numbness or weakness of face, arm or leg Confusion and or trouble speaking or understanding Trouble seeing in one or both eyes Trouble walking, dizziness and or loss of balance or coordination Sever headache with no known reason |
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Intake of fats
Summary |
Total fats - 20-30% of cal
Sat fat - <10% of cal PUFA - <10% of cal MUFA - <20% of cal EFA - .6-1.2% w-3, 5% w-6 CHO - <300mg Trans fat - as low as possible |
