Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42The Lipids: The Lipids: Triglycerides, Triglycerides, Phospholipids, and Phospholipids, and SterolsSterolsChapter 5 (Lecture #2)Chapter 5 (Lecture #2)Dr. Alisha RovnerDr. Alisha RovnerUniversity of DelawareUniversity of DelawareNutrition Concepts (NTDT200)Nutrition Concepts (NTDT200)Fall 2013Fall 2013Lecture ObjectivesLecture Objectives•Recognize the chemistry of fatty acids and triglycerides and differences between saturated and unsaturated fats. •Describe the chemistry, food sources, and roles of phospholipids and sterols.•Summarize fat digestion, absorption, and transport.Lecture ObjectivesLecture Objectives•Explain the relationships among saturated fat, trans fat, and cholesterol and chronic diseases, noting recommendations(how much consume in diet cannot increase disease).•Explain the relationships between monounsaturated and polyunsaturated fats and health, noting recommendations.Lipid ReviewLipid Review•Family of compounds that include:TriglyceridesPhosopholipidsSterols• Characterized by their insolubility in waterReview of TriglyceridesReview of Triglycerides•Glycerol backbone with 3 fatty acids•Predominant(commonly found) lipids in both food and in the body•Fatty acids vary in the length of their carbon chains, their degrees of unsaturation and the location of their double bondsImportant terms to knowImportant terms to know•Fats•Oils•Fatty acids•Saturated fatty acids•Unsaturated fatty acids•Hydrogenation•Trans FatsPhospholipidsPhospholipids•Unique chemical structure that allow them to be soluble in both fat and water•In food industry they are used as emulsifiers (fat & water can mix) (eg. lecithin)•In the body they are part of cell membranes, help fat soluble substances pass in and out of cellsp136Emulsifiers are substances with both water and fat soluble portions that promote the mixing of oils and fats (eg. Mayonnaise)Without help from emulsifiers, fats and water don’t mix.PhospholipidsPhospholipidsPhosopholipidsPhosopholipids•Lecithin supplements•Claims that it’s a major constituent of cell membranes, that cell membranes are essential to the integrity of cells therefore people must take a supplement(false body can make by self)•Supplements are NOT necessary because people make all of the lecithin they need (not an essential nutrient)•Large doses can cause GI distress, sweating and loss of appetiteSterolsSterols•Compounds containing a 4 ring carbon structure with any of a variety of side chains attached•Sterols in the body include: •Cholesterol•Bile acids•Steroid hormones•Vitamin DSterolsSterols•Cholesterol- most familiar sterol•Liver makes 800-1500 mg/day (endogenous)•Certain foods contain cholesterol (exogenous)•Only animal products contain cholesterol•Not inherently evil, body needs it•Harmful effects in the body occur when it accumulates in the artery walls and contributes to formation of plaqueSterolsSterolsFat soluble vitamin D is synthesized from cholesterol.Structurally very similar with the exception that cholesterol has a closed ring (highlighted in red) and vitamin D is open.Lipid DigestionLipid Digestion•Fats are hydrophobic (“fear of water”) so there’s a challenge in keeping the fats mixed with watery fluids in GI tract•Goal of fat digestion is to dismantle triglycerides into smaller molecules (monoglycerides, fatty acids, and glycerol) that the body can useLipid DigestionLipid Digestion•Mouth•Fat digestion starts off slowly here•Stomach•Churning grinds solids to finer particles, mixes chyme and disperses fat into small droplets•Gastric lipase hydrolyzes small amount of fat•Little fat digestion actually occurs hereLipid DigestionLipid Digestion•Small intestine•When fat enters it triggers release of cholecystokinin (CCK) to release bile which acts as an emulsifier•Fats are fully digested here•After bile emulsifies fat it’s either reabsorbed or excretedLipid AbsorptionLipid Absorption•The end products of fat digestion are (1) Monoglycerides (mostly), (2) Fatty acids (some), (3) Glycerol (very little)•Small molecules (short and medium chain fatty acids) can move directly into the bloodstream•Larger lipids (long chain fatty acids) combine with bile to form micelles that are water soluble.Absorption of FatAbsorption of FatLipid TransportLipid Transport•Lipoproteins solve the body’s challenge of transporting fats through watery bloodstream•Four main types of lipoproteins which can be distinguished by their size and density•Chylomicrons•Very-low-density lipoproteins (VLDL)•Low-density lipoproteins (LDL)•High-density lipoproteins (HDL)Lipid TransportLipid Transport4 main types of lipoproteins:(1) Chylomicrons- transport diet derived lipids from small intestines to the rest of the body(2) Very-low-density lipoproteins (VLDL)- Lipids made in liver are packaged with proteins and shipped to other parts of body(3) Low-density lipoproteins (LDL)- circulates throughout the body and makes their content available to cells of all tissues(4) High-density lipoproteins (HDL)- removes cholesterol from the cellsHealth Implications- HDL and LDLHealth Implications- HDL and LDL•Blood cholesterol linked to heart disease is LDL cholesterol (“bad cholesterol”)•High HDL (“good cholesterol”) has protective affect on heart. HDL represents cholesterol returning to liver for breakdown and excretion.Factors that Factors that LDL and/or LDL and/or HDL HDL•Weight control•Consuming mono or poly unsaturated fat rather than saturated fat•Soluble dietary fiber•Phytochemicals•Moderate alcohol consumption•Physical activityDesirable blood lipid profilesDesirable blood lipid profiles•Blood lipid profiles are blood tests that include total cholesterol, triglycerides and various lipoproteins•Desirable values (blood value)•Total cholesterol <200 mg/dL•LDL cholesterol <100 mg/dL•HDL cholesterol ≥ 60 mg/dL•Triglycerides <150 mg/dLHealth Effects of LipidsHealth Effects of Lipids•Elevated blood cholesterol major risk for cardiovascular disease (CVD). •Cholesterol accumulates in arteries, restricts
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