1 FATS (LIPIDS) Department of Applied Science King Saud University/ Community College By: Murad Sawalha

2 FATS (LIPIDS) Nature of fats: Nature of fats: –Are storage form of concentrated fuel –Fats are either solid or liquid oils –Either saturated fats or unsaturated –Not soluble in water, greasy. –Lipids are the chemical group name for organic substances of a fatty nature (fats, oil, & other fat related compounds) –Fats are composed of the same elements composing CHO, i.e. C, H, O

3 Classes of fats (lipids) Triglycerides: Triglycerides: - a class of lipids composed of a glycerol molecule as its backbone with 3 fatty acids attached. - a class of lipids composed of a glycerol molecule as its backbone with 3 fatty acids attached. - account for approximately 98% of the lipids in food and are the major storage form of fat in the body. - account for approximately 98% of the lipids in food and are the major storage form of fat in the body.

4 Classes of fats (lipids) Fatty acids (F.A): Fatty acids (F.A): - They are the main building blocks of fats. - They are the main building blocks of fats. - FA are Classified by their chain length: - FA are Classified by their chain length: 1) Short chain have (2-4) carbon atoms 1) Short chain have (2-4) carbon atoms 2) Medium chain have (6-10). 2) Medium chain have (6-10). 3) Long (more than 12) carbon atoms. 3) Long (more than 12) carbon atoms. - The chains are made up of carbon atoms with a methyl group (-CH3) on one end & a carboxyl group (-COOH) on the other end. - The chains are made up of carbon atoms with a methyl group (-CH3) on one end & a carboxyl group (-COOH) on the other end. - Fatty acids have 2 significant characteristic: saturation & essentiality. - Fatty acids have 2 significant characteristic: saturation & essentiality.

5 FATTY ACIDS Saturated (filled with H atoms) and unsaturated (unfilled with H atoms at one or more spots) Saturated (filled with H atoms) and unsaturated (unfilled with H atoms at one or more spots) Essential F.A (can not be synthesized by the body) and Non Essential (can be synthesized by the body) Essential F.A (can not be synthesized by the body) and Non Essential (can be synthesized by the body)

6 FATTY ACIDS Saturation Saturated F.As: saturated with H atoms, no double bonds, heavier, denser and more solid, mostly of animal origin (e.g. meat fat, eggs, dairy, … etc Saturated F.As: saturated with H atoms, no double bonds, heavier, denser and more solid, mostly of animal origin (e.g. meat fat, eggs, dairy, … etc Unsaturated F.As: with one or more double bonds, less heavier (a liquid oil) Unsaturated F.As: with one or more double bonds, less heavier (a liquid oil) 1) Some are monounsaturated fat (olives & olive oils, peanuts & peanuts oil, canola oil (rapeseed), almonds, pecans, avocado 1) Some are monounsaturated fat (olives & olive oils, peanuts & peanuts oil, canola oil (rapeseed), almonds, pecans, avocado

7 FATTY ACIDS Saturation 2) Polyunsaturated F.As: having two or more double bonds (e.g. Vegetable oils, safflower, corn, cottonseed, soybean) 2) Polyunsaturated F.As: having two or more double bonds (e.g. Vegetable oils, safflower, corn, cottonseed, soybean) Fats from plants are usually unsaturated except coconut, palm oil Fats from plants are usually unsaturated except coconut, palm oil

8 FATTY ACIDS Essentiality Essential fatty acids:: Essential fatty acids:: - They are essential nutrients: - They are essential nutrients: 1)Its absence cause a specific deficiency disease 1)Its absence cause a specific deficiency disease 2)The body can not manufacture them and must obtain them from outside in the diet 2)The body can not manufacture them and must obtain them from outside in the diet - The only fatty acids known to be essential for complete human nutrition are the polyunsaturated fatty acids linoleic & linolenic. - The only fatty acids known to be essential for complete human nutrition are the polyunsaturated fatty acids linoleic & linolenic.

9 FATTY ACIDS Essentiality Linoleic acid is found in vegetable oils: Linoleic acid is found in vegetable oils: (DRIs): (17 gm / day for men) (DRIs): (17 gm / day for men) (12 gm / day for women) (12 gm / day for women) Linolenic acid is found in milk, soyabean Linolenic acid is found in milk, soyabean (DRIs): (1.6 gm / day for men) (DRIs): (1.6 gm / day for men) (1.1 gm / day / women) (1.1 gm / day / women) They have important functions: They have important functions: - Tissue strength, cholesterol metabolism, muscle tone, blood clotting, & heart action - Tissue strength, cholesterol metabolism, muscle tone, blood clotting, & heart action

10 LIPOPROTEINS FAT + PROTEIN (APOPROTEIN) FAT + PROTEIN (APOPROTEIN) Major vehicles in transport function in blood Major vehicles in transport function in blood Lipoproteins contain triglycerides, cholesterol, other minerals and vitamins Lipoproteins contain triglycerides, cholesterol, other minerals and vitamins Their density is proportionate to the protein load. Their density is proportionate to the protein load. The higher protein load, the higher lipoproteins density. The higher protein load, the higher lipoproteins density. The higher the fat load, the lower the lipoprotein density. The higher the fat load, the lower the lipoprotein density.

11 LIPOPROTEINS Low density lipoproteins (LDLs): carry fat & Cholesterol to the cells of the body Low density lipoproteins (LDLs): carry fat & Cholesterol to the cells of the body High density lipoproteins (HDLs): carry free cholesterol from body tissues to the liver to be broken and then excreted. High density lipoproteins (HDLs): carry free cholesterol from body tissues to the liver to be broken and then excreted. Lipids are associated with lipids disorders, blood vessels, and heart diseases (atherosclerosis) Lipids are associated with lipids disorders, blood vessels, and heart diseases (atherosclerosis) - Hyperlipidemia: the condition of an elevated level of blood fats. - Hyperlipidemia: the condition of an elevated level of blood fats.

12 CHOLESTEROL IT IS NOT A FAT IT IS NOT A FAT IT IS FROM A DIFFERENT CHEMICAL GROUP CALLED STEROLS IT IS FROM A DIFFERENT CHEMICAL GROUP CALLED STEROLS It is vital in human metabolism It is vital in human metabolism Present in all animal tissue particularly egg yolk, organ meat as liver and kidneys and meat Present in all animal tissue particularly egg yolk, organ meat as liver and kidneys and meat Not found in plants food Not found in plants food It is synthesized in the liver, adrenal cortex, skin, intestines, testes and ovaries It is synthesized in the liver, adrenal cortex, skin, intestines, testes and ovaries

13 CHOLESTEROL The body does not need cholesterol from outside, so there is no biological requirements for it The body does not need cholesterol from outside, so there is no biological requirements for it Also no DRIs set for cholesterol consumption Also no DRIs set for cholesterol consumption It is connected with the occurrence of coronary heart diseases It is connected with the occurrence of coronary heart diseases

14 FUNCTIONS OF FATS 1) Energy: - Its a fuel for energy production - Its a fuel for energy production - Caloic (fuel )value of fats is 9 Kcal/ gm - Caloic (fuel )value of fats is 9 Kcal/ gm - Storage form of body fuel (excess CHO is changed into fats) 2) Essential nutrients: - Provide essential fatty acids for production of other fats and cholesterol - Aid in absorption of fat soluble vitamins

15 FUNCTIONS OF FATS 3) Flavor and Satisfaction: Some fat adds flavor to foods, & contributes to a feeling of satisfaction after meal (low rate of gastric emptying and digestion) Some fat adds flavor to foods, & contributes to a feeling of satisfaction after meal (low rate of gastric emptying and digestion) 4) Fat Substitutes: several fat substitutes are being marketed without added Kcalories, and not even absorbed, but gives the fat flavor e.g. simplesse, and olestra

16 FAT in the body Fat in the body: Fat in the body: 1. Adipose tissue: supports, protects vital organs, under the skin (heat regulation), in myelin sheaths of nerves (relay nerve impulse) 2. Cell membranes structure: forms the fatty center, regulates the cell membrane transport

17 FAT SOURCES Food Sources of Fat: Food Sources of Fat: 1. Animal fats: animal sources (saturated fat) e.g. meat fat, dairy fat products (cream, ice-cream, butter, cheese), egg yolk, red meat (veal, beef, pork, lamb), poultry, shelfish, fish 2. Plant fat: - Mostly unsaturated; mono and polyunsaturated fat - Mostly unsaturated; mono and polyunsaturated fat - In vegetable oils (safflower, corn, cottonseed, peanut, olives, soybeans) - In vegetable oils (safflower, corn, cottonseed, peanut, olives, soybeans) - Coconut & palm oils are exception (saturated fat) - Coconut & palm oils are exception (saturated fat)

18 FAT SOURCES 3. Hydrogenated Fat: margarine and shortenings, sometimes fortified with vitamins A &D Risks of high saturated fat diet and cholesterol: 1. Some cancers3. diabetes mellitus 2. Coronary heart diseases4. obesity

19 FAT SOURCES Characteristics of food sources: Characteristics of food sources: Food fats are classified into: visible and invisible fats, to help individuals become aware of all food sources of fat Food fats are classified into: visible and invisible fats, to help individuals become aware of all food sources of fat Visible fat: plain to see and include: butter, margarine, separate cream, salad oils, and dressing, lard, shortenings, fat meal Visible fat: plain to see and include: butter, margarine, separate cream, salad oils, and dressing, lard, shortenings, fat meal Invisible fat: include cheese, cream portion Invisible fat: include cheese, cream portion

20 FAT SOURCES Of a homogenized milk, egg yolk, nuts, seeds, olives, avocados, lean meat Of a homogenized milk, egg yolk, nuts, seeds, olives, avocados, lean meat BODY NEEDS OF FAT: BODY NEEDS OF FAT: Dietry fat and health Dietry fat and health Not more than 20 – 35 % of the total caloric requirements should come from fat Not more than 20 – 35 % of the total caloric requirements should come from fat Diseased individuals should stick to 15 – 25 % to provide the needed F.F. Diseased individuals should stick to 15 – 25 % to provide the needed F.F.

21 HEALTH PROMOTION The trends of health promotion and disease prevention is through reduction of risk factors related to chronic diseases The trends of health promotion and disease prevention is through reduction of risk factors related to chronic diseases Excess dietary fat, particularly saturated fat, cholesterol, hypertension, stress, lack of exercise, obesity, diabetes mellitus, elevated blood lipids all predispose to heart diseases Excess dietary fat, particularly saturated fat, cholesterol, hypertension, stress, lack of exercise, obesity, diabetes mellitus, elevated blood lipids all predispose to heart diseases

22 DIGESTION OF FAT 1. In the Mouth: lingual lipase, secreted from glands at the back of tongue, has little effect + mechanical breakdown 2. Stomach: little if any chemical digestion by gastric lipase tributrinase 3. Small intestine: chemical digestion through 3 major sources: a) Liver bileb) pancreatic lipases c) intestinal enzymes

23 DIGESTION OF FAT a) Bile from the gall bladder: fat is emulsified by bile into small particles with large surface are and lower surface tension in an alkaline medium b) Pancreatic enzymes: I. Pancreatic lipase: powerful enzyme, completes digestion of fats into FFA + glycerol, monoglycerides, some fat remain as such for excretion II. Cholesterol estrase: on cholesterol esters

24 DIGESTION OF FAT c) Enzymes from the small intestine: Lecithinase which acts on lecithin (another lipid compound) Absorption of fats: MICELLESCHYLOMICRONS Lymphatic circulation