Phospholipids and Sterols

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The Lipids: Triglycerides, Phospholipids, and Sterols - Library

7/18/2012The Lipids:Triglycerides,Phospholipids, andSterolsChapter 5• Poor health• Too much fat• Too little fatIntroduction• Too much of some kinds of fat• Family of lipids• Triglycerides• PhospholipidsSterolsWhitney & Rolfes – Understanding Nutrition, 12 thEditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionChemist’s View of Fatty Acidsand Triglycerides• Energy provided per gram• More carbons and hydrogens• Preview of lipids• Triglycerides: glycerol and 3 fatty acids• Fatty acids: even number of carbons• Fatty acids: saturated or unsaturated• Omega-3 and omega-6 fatty acidsWhitney & Rolfes – Understanding Nutrition, 12 th Edition• Fatty acidsChemist’s View of Fatty Acidsand Triglycerides• Organic acid• Methyl group at one end; acid group at otherend• Usually even number of carbons• 18-carbon fatty acids abundant in food• Saturations• Saturated – full of hydrogens• Unsaturated – missing hydrogensWhitney & Rolfes – Understanding Nutrition, 12 th Edition1


7/18/2012Chemist’s View of Fatty Acidsand Triglycerides• Fatty acids• Location of double bonds• Nearest the methyl end of the carbon chain• Omega number• Linolenic acid• Monounsaturated fatty acids• Omega-9 groupsChemist’s View of Fatty Acidsand Triglycerides• Triglycerides• Glycerol backbone• Three fatty acids• Formed via series of condensation reactions• Usually contain mixture of fatty acidsWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionChemist’s View of Fatty Acidsand TriglyceridesChemist’s View of Fatty Acidsand TriglyceridesWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition2


7/18/2012Chemist’s View of Fatty Acidsand Triglycerides• Degree of unsaturation• Firmness• Polyunsaturated fats• Saturated fats• Length of carbon chain• Stability• Oxidation and spoilage of fatsChemist’s View of Fatty Acidsand Triglycerides• Degree of unsaturation• Hydrogenation• Advantages• Trans-fatty acids• Configurations – cis and trans• Similarity to other types of fatWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionChemist’s View of Fatty Acidsand TriglyceridesChemist’s View of Fatty Acidsand TriglyceridesWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition3


7/18/2012Chemist’s View ofPhospholipids and SterolsPhospholipids• Solubility in fat and water• Emulsifiers in food industry• Lecithin• Food sources• Roles• Part of cell membranes• EmulsifiersChemist’s View ofPhospholipids and SterolsSterols• Food sources• Cholesterol• Plant sterols• Roles of sterols• Body compounds made from cholesterolWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionLipid DigestionLipid Digestion• Fats are hydrophobic• Digestive enzymes are hydrophilic• Goal of fat digestion• Dismantle triglycerides• Monoglycerides, fatty acids, and glycerolWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition4


7/18/2012Lipid DigestionLipid Digestion• Mouth• Lingual lipase• Stomach• Strong muscle contractions• Gastric lipaseWhitney & Rolfes – Understanding Nutrition, 12 th Edition• Small intestine• Cholecystokinin (CCK)• Gall bladder releases bile• Bile acts as emulsifier• Pancreatic lipase• Hydrolysis• Triglycerides and phospholipids• Bile routes• Blood cholesterol levelsWhitney & Rolfes – Understanding Nutrition, 12 th EditionEmulsification of Fat by BileHydrolysis of a TriglycerideWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition5


7/18/2012Enterohepatic Circulation ofBileIn the gallbladder,bile is stored.In the liver,bile ismade fromcholesterol.In the small intestine,bile emulsifies fats.In the colon, bile that hasbeen trapped by solublefibers is lost in feces.Whitney & Rolfes – Understanding Nutrition, 12 th EditionStepped ArtFig. 5-16, p. 144Lipid AbsorptionAbsorption of Fat• Directly into bloodstream• Glycerol and short- & medium-chain fattyacids• Lymphatic system• Micelles diffuse into intestinal cells• Reassembly of triglycerides• Packed with proteins – chylomicrons• Bypass liver at firstWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition6


7/18/2012Lipid TransportLipid Transport• Four main types of lipoproteins• Chylomicrons• Largest and least dense• Transport diet-derived lipids• Liver removes remnants from blood• Very-low-density lipoproteins (VLDL)• Made in the liver• Proportion of lipid shiftWhitney & Rolfes – Understanding Nutrition, 12 th Edition• Four main types of lipoproteins• Low-density lipoproteins (LDL)• Cell needs• Liver regulation• High-density lipoproteins (HDL)• Remove cholesterol from cells• Carry cholesterol to liver for recycling• Anti-inflammatory properties• Health implicationsWhitney & Rolfes – Understanding Nutrition, 12 th EditionLipid TransportRole of TriglyceridesWhitney & Rolfes – Understanding Nutrition, 12 th Edition• Provide the cells with energy• 9 kcalories per gram• Virtually unlimited ability to store fat energyin body• Adipose tissue• Secretes hormones• Adipokines• Skin insulation, shock absorption, cellmembranes, and cell signaling pathwaysWhitney & Rolfes – Understanding Nutrition, 12 th Edition7


7/18/2012Whitney & Rolfes – Understanding Nutrition, 12 th EditionEssential Fatty Acids• Linoleic acid – Omega-6 fatty acid• Sources• Linolenic acid – Omega-3 fatty acid• Sources• DHA• EPA• Eicosanoids• Fatty acid deficienciesWhitney & Rolfes – Understanding Nutrition, 12 th EditionA Preview of LipidMetabolism• Adipose cells store fat after meals• Lipoprotein lipase• Hydrolyzes triglycerides• Triglycerides reassembled inside adiposecells• Using fat for energy• Protein sparing• Energy deprivation• Fasting and ketone bodies• Heart diseaseWhitney & Rolfes – Understanding Nutrition, 12 th EditionHealth Effects of Lipids• Elevated blood cholesterol• Saturated fat – increase LDL cholesterol,promote blood clotting• Dietary choices• Trans-fats – increase LDL cholesterol• Dietary cholesterol• Heart diseaseWhitney & Rolfes – Understanding Nutrition, 12 th EditionHealth Effects of Lipids• Monounsaturated fats• Replace saturated and trans fats• Reduces blood cholesterol• Dietary sources• Omega-3 fats• Benefits• Dietary sources• Omega-6 to omega-3 ratio8


7/18/2012Health Effects of Lipids• Cancer• Promotion rather than initiation of cancer• Dietary fat and cancer risk• Differs for various types of cancer• Obesity• Cutting fat from diet reduces kcalories• Dietary recommendationsRecommended Intakes of Fat• DRI and Dietary Guidelines• Diet low in saturated and trans fat• Diet low in cholesterol• 20 to 35 percent of daily energy from fat• AI set for linoleic and linolenic acids• Daily Values (DV) on food labels• Saturated fat and cholesterol• Risk of insufficient fat intakeWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionFrom Guidelines to Groceries• Fat-soluble vitamins• A, D, E, and K• Flavor, texture, and palatability• Meats and meat alternatives• Selections• Milk and milk products• SelectionsFrom Guidelines to Groceries• Vegetables, fruits, and grains• Lowers consumption of various fats in thediet• Invisible fat• Fried and baked goods• Choose wisely• Unprocessed foodsWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition9


7/18/2012From Guidelines to Groceries• Fat replacers• Types• Risks• Read food labels• Total fat, saturated fat, trans fat, andcholesterol• Compare products• % Daily Value vs. % kcalories from fatButter and Margarine LabelsComparedWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionGuidelines for Fat IntakeHighlight 5High-Fat Foods – Friend or Foe?• Limit saturated fat and trans fat intake• Moderate kcalories• Enough fat for good health• Not too much of the harmful fats• DRI recommendations• Compatible with low rates of diseaseWhitney & Rolfes – Understanding Nutrition, 12 thEditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition10


7/18/2012High-Fat Foods and HeartHealth• Olive oil• Benefits for heart health• Replace saturated fats• Nuts• LDL cholesterol• Fat composition• Benefits for heart health• Cautious advice for dietary inclusionHigh-Fat Foods and HeartHealth• Fish• Omega-3 fatty acids• Benefits for heart health• Environmental contaminants• Dietary recommendationsWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionHigh-Fat Foods and HeartHealthHigh-Fat Foods and HeartDisease• Saturated fat and LDL cholesterol• Sources of saturated fat in the U.S.• Meats• Whole milk products• Tropical oils• Zero saturated fat is not possible• Trans fat• Limit hydrogenated foodsWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition11


7/18/2012High-Fat Foods and HeartDiseaseHigh-Fat Foods and HeartDiseaseWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th EditionHigh-Fat Foods and HeartDisease• TraditionallyThe Mediterranean Diet• Low in saturated fat• Very low in trans fat• Rich in unsaturated fat• Rich in complex carbohydrate and fiber• Rich in nutrients and phytochemicals• Benefits for heart disease riskWhitney & Rolfes – Understanding Nutrition, 12 th EditionWhitney & Rolfes – Understanding Nutrition, 12 th Edition12

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