Chapter 4 Lipids PDF

Chapter 4: Lipids Dr. Raed Ali Jaradat Lecturer of Nursing Mutah University  Lipids A group of water-insoluble, energy-yielding organic compounds composed of carbon, hydrogen, and oxygen atoms Lipids, commonly known as fats that include: 1. triglycerides (fat & oils)...

Chapter 4: Lipids Dr. Raed Ali Jaradat Lecturer of Nursing Mutah University  Lipids A group of water-insoluble, energy-yielding organic compounds composed of carbon, hydrogen, and oxygen atoms Lipids, commonly known as fats that include: 1. triglycerides (fat & oils) which represents 95% of the total fat intake 2. phospholipids (lecithin) 3. sterol (cholesterol) * Dr. Raed Ali Jaradat 2  Composition of fat Fat are made of the elements carbon, hydrogen, & oxygen in the form of one glycerol molecule with one, two, or three fatty acids attached. Although fats contain the same elements as CHO, they have less oxygen & more hydrogen & carbon atoms; because of this, they are higher in calories * Dr. Raed Ali Jaradat 3  Composition of fat Glycerol: Is an alcohol made of a three-carbon atom with alcohol groups attached to each; all glycerol molecules are the same. After fat is broken down through the process of digestion into fatty acids & glycerol, the glycerol molecule is absorbed directly into the portal vein. * Dr. Raed Ali Jaradat 4  Composition of fat: (cont’d) b- Fatty Acids: Are composed of a straight chain of carbon atoms with hydrogen atoms attached & an acid group (COOH) at one end & a methyl group (CH3)at the other end. Most fatty acids have an even number of carbon atoms ranging from 2 to 24. Short chain F.A. contain 2 - 4 carbon atoms Medium chain F. A. contain 6 – 12 carbon atoms * Dr. Raed Ali Jaradat 5  Fat includes 1-Triglycerides A class of lipids composed of a glycerol molecule as its backbone with 3 fatty acids attached. account for approximately 95% of the lipids in foods and are the major storage form of fat in the body Diglycerides consist of glyceride molecules that have 2 fatty acid Monoglycerides have one fatty acid attached * to one a Dr.glyceride Raed Ali Jaradat 6  Triglycerides (cont’d) 99% are classified as mixed because they contained more than one kind of F.A. For example: triglyceride may contain one saturated F.A. , one monounsaturated F.A., & one PUFA. Simple triglycerides which contain three molecules of the same fatty acid * Dr. Raed Ali Jaradat 7  Types of Fat Fatty Acids: – Organic acid units that make up fat. There are three types… 1. Saturated 2. Polyunsaturated 3. Monounsaturated * Dr. Raed Ali Jaradat 8  Saturated Fatty acids Each carbon atom has 4 bonding sites; when all 4 sites hold single bond, that carbon atom said to be saturated with the maximum number of hydrogen atoms No double bond exist All short- and medium- chain fatty acids are saturated Appear to raise the level of LDL (“bad”) cholesterol in the bloodstream * Dr. Raed Ali Jaradat 9  Saturated Fatty acids Food fats that are high in saturated fatty acids tend to be solid at room temperature & have high melting points. With the exception of those found in poultry & freshwater fish, all animal fats are high in saturated fats (butter, beef) The only saturated vegetable fats are coconut, palm oils. They are more stable than unsaturated They are animal in origin * Dr. Raed Ali Jaradat 10  sources Fats & oils % 1. Coconut oil 88% 2. Palm oil 81% 3. Butter 65% 4. Beef fat 53% * Dr. Raed Ali Jaradat 11  Unsaturated Fats Are not saturated with hydrogen atoms, so double bonds form between the carbon atoms to satisfy nature’s law that each carbon atom must have 4 bonds connecting it to other atoms Monounsaturated fatty acids: have only one double bond between carbon atoms polyunsaturated fatty acids (PUFA): have 2 or more double bonds * Dr. Raed Ali Jaradat 12  Unsaturated Fats 0mega-3 fatty acids: are PUFA that have their first double bond 3 carbon atoms from the methyl carbon atom Sources: cold water fish, fish oil, tuna, salmon, sardines, green leafy vegetable, nuts, soybean walnuts, hazelnuts Benefits of omega- 3 FA: 1. Lower triglyceride level 2. Reduce blood pressure 3. Inhibit the development of cancer 4. Has anti-inflammatory effect (RA, asthma, ulcerative colitis 5. Decrease incidence of stroke * Dr. Raed Ali Jaradat 13  Unsaturated Fats Foods fats that are high in unsaturated fatty acids tends to be soft or liquid at room temperature & have low melting points, susceptible to rancidity when exposed to light & O2, found mostly in plant fats & oils except of coconut, palm. Examples: 1. sunflower 2. margarine 3. corn 4. soybean 5. cottonseed 6. cashew nut 7. walnut 8. olive oil 9. peanut oil 10. chicken, turkey, egg * Dr. Raed Ali Jaradat 14  Monounsaturated fats & oils Fats & oils % Olive oil 71% Peanut oil 49% Soft margarine 47% Chicken, turkey 42% * Dr. Raed Ali Jaradat 15  Polyunsaturated fats & oils Fats & oils % 1. Sunflower oil 64% 2. Soybeans oil 58% 3. Corn oil 55% * Dr. Raed Ali Jaradat 16  All fats include all 3 kinds of fatty acids, but in varying amounts. Each type of fat has a different effect on cholesterol levels * Dr. Raed Ali Jaradat 17  Hydrogenated Fats Are unsaturated vegetables oils (corn, soybean, cottonseed, peanut, or olive) that have hydrogen atoms added to some of the double bonds to make the fat more saturated, to improve the stability of a fat or oil, change its texture & increase its functionality This forms a new type of fatty acid called trans fatty acid. Trans fatty acids have many of the same properties as saturated fats * Dr. Raed Ali Jaradat 18  Visible Fat Fat that is easily seen Examples: Butter on a baked potato, layer of fat around meat, etc. * Dr. Raed Ali Jaradat 19  Invisible Fat Fat that cannot be detected by the eye Examples: whole milk, some cheese, egg yolks, nuts, avocados, etc. * Dr. Raed Ali Jaradat 20  Fat includes 2- Other Lipids: account for 5% a- Phospholipids: Are group of compound lipids that are similar to triglycerides in that they contain a glycerol molecule & two fatty acids. In place of the third fatty acid, phospholipids have a phosphate group to which is attached a molecule of choline or another nitrogen-containing compound. Phospholipids are found naturally in almost all food, & because they are soluble in both water & fat, they are used extensively by the food industry as emulsifier The fatty acids make phospholipids fat-soluble. Phosphate group makes them water-soluble. * Dr. Raed Ali Jaradat 21  Functions:/1 1. serve as structural component of cell membrane 2. transport fat-soluble, water-soluble substances across cell membrane 3. precursors of prostaglandin, a group of fatty acid derivatives with hormonelike actions that perform the following functions: * Dr. Raed Ali Jaradat 22  Functions Function of prostaglandin 1. help regulate blood pressure 2. assist with nerve impulse transmission 3. regulate gastric secretion & muscular contraction of GIT 4. stimulate uterine contraction 5. induce labor & abortion 6. inhibit lipid catabolism 4. Work as emulsifiers to keep fats suspended in the blood & other body fluids * Dr. Raed Ali Jaradat 23  Sources 1. Liver 2. eggs 3. wheat 4. peanuts * Dr. Raed Ali Jaradat 24 Alert ??????!!!!!!! it is untrue that Lecithin (best known phospholipids) lowers blood cholesterol; improve memory, controls weight, cure arthritis, hypertension, & gallbladder problems. Because it is digested in the GIT into its component parts, not absorbed intact to perform super functions. Lecithin is not even an essential nutrient, because it is synthesized in the body. Many people who take lecithin supplements do not realize that they provide 9 cal/g, just like all fats in the diet. * Dr. Raed Ali Jaradat 25  2- Other Lipids: account for 5% b- Cholesterol (sterol) Cholesterol is NOT fat. It is a “fat-like” substance present in all body cells that is needed for many essential body processes. Cholesterol is a member of the sterol family which includes (bile acids, sex hormones, adrenocortical hormones, & vitamin D. It is not essential in the diet because it is synthesized primarily in the liver from glucose or saturated fatty acids. Is found in all cell membranes & in myelin; brain & nerve cells Used to synthesize bile acids, steroid hormones, Vitamin D * Dr. Raed Ali Jaradat 26  b- Cholesterol (sterol) High fiber diet enhance the excretion of bile acids & therefore reduces cholesterol in the body Found in all animal products with the exception of egg whites. Organ meats & egg yolks, are the richest sources of Cholesterol; smaller amounts are found in muscle meats, shellfish, poultry, & dairy products * Dr. Raed Ali Jaradat 27 C- Lipoprotein Are compound lipids that contain both protein & various types & amounts of lipids. They are made mostly in the liver & are used to transport water- soluble lipids through the blood. Elevated level of certain kinds of lipoprotein represent a risk factor for the development atherosclerosis * Dr. Raed Ali Jaradat 28  C- Lipoprotein Classification of lipoprotein: 1. Very-low-density lipoprotein (VLDL): contains triglycerides (50%) with some protein & cholesterol. Transport lipids (triglycerides, cholesterol) from the liver to the tissues. High serum VLDL level may increase the risk of atherosclerosis 2. Low-density lipoprotein (LDL): composed of cholesterol. LDL function to transport cholesterol from the liver to the tissues. High serum LDL level increase the risk of atherosclerosis. Diet that are high saturated fat are associated with elevation of LDL cholesterol * Dr. Raed Ali Jaradat 29  Classification of lipoprotein: 3. High-density lipoprotein (HDL): contain primarily protein, with small amounts of triglycerides & cholesterol. Transport cholesterol from the tissues to the liver to be metabolized. High serum levels are protective against the development of atherosclerosis * Dr. Raed Ali Jaradat 30  HOW THE BODY HANDLES FAT * Dr. Raed Ali Jaradat 31  HOW THE BODY HANDLES FAT DIGESTION: – Amount of chemical digestion occurs in the mouth & stomach through the action of lingual lipase & gastric lipase – As fat enters the duodenum, it stimulate the release of the hormone cholecystokinin, which stimulate the gallbladder to release bile (which is not enzyme but it is emulsifier). – Bile is continually produced in the liver & concentrated & stored in the gallbladder which contains bile salt, cholesterol, bilirubin, & electrolytes). * Dr. Raed Ali Jaradat 32  HOW THE BODY HANDLES FAT DIGESTION: (cont’d) – As an emulsifier, bile breaks down fat globules into smaller particles to increase the surface area on which pancreatic lipase can work. – Most fat digestion occurs in the small intestine. Pancreatic lipase splits off one fatty acid at from triglyceride molecule – 4 – 5 g escape digestion & excreted in the feces – End-product for absorption are Monoglycerides, fatty acids & glycerol * Dr. Raed Ali Jaradat 33  HOW THE BODY HANDLES FAT ABSORPTION: About 95% of consumed fat is absorbed, mostly in the duodenum & jejunum Small fat particles such as short chain fatty acids & glycerol, are absorbed directly through the mucosal cells into portal vein & are transported to the liver METABOLISM: After entering the bloodstream, lipids are transported to either the liver or adipose tissue. * Dr. Raed Ali Jaradat 34  HOW THE BODY HANDLES FAT Metabolism Triglycerides are broken down into glycerol & F.A. by lipoprotein lipase glycerol & F.A enter cells where catabolized for energy or rebuilt into triglycerides for storage Adipose cell give up stored fat when an enzyme within adipose (hormone-sensitive lipase) react to the need for energy by splitting TG into glycerol & F.A., which are released to bloodstream Regulated by hormones: 1. ACTH, epinephrine glucagon, Glucocorticoids, Thyroxine. promote fat mobilization (catabolism) 2. Insulin stimulate fat synthesis (anabolism) * Dr. Raed Ali Jaradat 35  1- FAT ANABOLISMM fatty acid synthesis: With the exception of the essential fatty acids, the body can synthesize fatty acids from acetyl-A; thus an excess of calories from any dietary source can be used. A group of enzymes known as fatty acid synthetases catalyze the series of reaction that take place in the liver * Dr. Raed Ali Jaradat 36  1- FAT ANABOLISMM Triglyceride synthesis: Liver can synthesize triglycerides from an excess intake of CHO or protein through the process of lipogenesis. In which glucose is converted to glycerol & fatty acids, which then be synthesized into triglycerides for storage in adipose tissue, or converted to lipoprotein, phospholipids, or cholesterol as needed. * Dr. Raed Ali Jaradat 37  2- FAT CATABOLISM: If the body is to use stored fat for energy, lipases within the cells must first split the triglycerides into their component parts – a glycerol & fatty acids The glycerol then converted to glucose (gluconeogenesis) Through a series of reactions, fatty acids catabolized by the liver (β oxidation) to two-carbon fragments. These fragments known as acetyl coenzyme A (co-A), can be oxidized for energy During normal fat metabolism, small quantities of ketones bodies are formed (ketogenssis) & used for energy. When fat catabolism is excessive , such as in DM, ketones accumulated in the blood leading to the condition known as ketosis * Dr. Raed Ali Jaradat 38  Hormones affecting fat metabolism Hormone Effect on fat metabolism 1. ACTH increase fat metabolism 2. Epinephrine increase the rate of fat metabolism 3. Glucagons increase but decrease fat synthesis 4. Glucocorticoids increase the rate of fat metabolism 5. Insulin stimulate fat synthesis 6. Thyroxine increase the rate of fat metabolism 7. GH stimulate the release of free fatty acids from adipose tissue * Dr. Raed Ali Jaradat 39  Fat intake guidelines limit fat to 30% or less of total calories limit saturated fat less than 10% of total calories limit cholesterol to 300 mg / day For someone consuming 1600 cal. /day. A total of 53 g of fat daily. 1600 cal * 0.3=480 cal 480 cal / 9 cal = 53.3 g total fat And less than 18 g of saturated fat daily: 1600 cal * 0.1 = 160 cal 160 cal / 9 cal/g = 18 g saturated fat * Dr. Raed Ali Jaradat 40  Fat excess Fat excess increases the risk for the following: obesity coronary heart disease: lead to elevate serum cholesterol & lipoprotein levels certain types of cancer: increase risk of cancers of colon, rectum, prostate, & endometrium * Dr. Raed Ali Jaradat 41  Fat deficiency Inadequate intake of calories is most likely related to the following problems: – disease- or drug induced anorexia (cancer therapies) – anorexia nervosa – altered digestion & absorption, associated with pancreatic insufficiency, celiac sprue, lactose intolerance * Dr. Raed Ali Jaradat 42  Function 1. Energy 2. Support & protection for internal organs 3. Temperature regulation 4. Absorption of fat-soluble vitamins * Dr. Raed Ali Jaradat 43  SOURCES OF FAT Animal sources account for 57% of total fat intake, & plant fat account for 43% The top of five sources of fat are: – Beef – Margarine – Salad dressing / mayonnaise – Milk – Cheese – Cakes / doughnuts Vegetables contain little fat or no fat Fruits do not contain fat except; avocado, coconut, coconut milk, olive oil Meat, poultry, fish, dry beans, eggs, nuts group * Dr. Raed Ali Jaradat 44 THE END A N K R H O S