1 Midterm - 2 November 2015 In class 50 minutes Start 12:55 sharp 55 multiple choice questions –1 point each 1 short answer-10 points from lecture 1a until end of lecture 6c

2 Carbohydrate/lipid/protein/alcohol 4/9/4/7 kcal/gram 17/37/17/29 kJ/gram Note alcohol = ethanol

The new normal-Globe and Mail- 30 September parents do not recognise when they and/or others including kid(s) is/are overweight or obese Fat is the new normal

4 Lecture 5a 5 Oct Lipids I 94/80

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10 Overview of lecture 5a 1) Lipids defined 2) Functions of fats in foods 3) Structure, classification, presence in food and function of: a) fatty acids b) triglycerides c) phospholipids d) cholesterol 4) Ingestion, digestion, absorption, transport, metabolism and excretion 6) Functions of lipids-essential or not

11 1)Lipids defined p. 130 family of compounds that includes triglycerides, (TG), phospholipids (PL) and sterols other definition water insoluble organic compounds made up of C, H, and O like carbohydrates but less O and therefore 9 vs 4 kcal/gm

12 2)Functions of fats in foods absorbing flavours and aromas of ingredients providing flavour of its own creamy and smooth mouth taste tenderizing and adding moisture

13 a)Triglycerides-fatty acids-structure, classification, p Organic acid Saturated 14:0 Monounsaturated 18:1 Polyunsaturated 18:2 n-6 18:3 n-6 (gamma-linolenic acid) 18:3 n-3 (alpha-linolenic acid)

14 REPLACE WITH FIG 5-2 ACETIC ACID Fig. 5-1, p. 140

p. 134

p. 135

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22 a)Triglycerides-fatty acids-structure, classification, p Glycerol + 3 fatty acids make a triglyceride Mixed triglycerides

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Fig. 5-4, p. 137

26 Triglycerides continued Triglycerides in food Processed fat-fat manipulated mechanically or chemically -chemical manipulation-hydrogenation- -hydrogenation yields trans-fatty acids

Fig. 5-7, p. 138

Fig. 5-8, p. 139

29 A)- Triglycerides- in foods and function In foods-triglycerides are most of the fat in our foods (followed by sterols followed by phospholipids) Function in our bodies-triglycerides are an energy source and a major storage form of energy in our bodies

30 B) Phospholipids- structure, classification, in foods and function p. 136 Structure- 2 FATTY ACIDS (FA) and polar head group-generally but exceptions Classification Choline-containing phospholipids Ethanolamine-containing phospholipids Phosphatidylserine Phospatidylinositol Sphingomyelin

Fig. 5-9, p. 140

32 Phospholipids continued Foods- found naturally Function p. 140 Membranes Lipoproteins Cell signalling

33 C) Sterols- structure, classification, in foods and function p. 137 Structure-Ring structure Classification-Sterols

Fig. 5-11, p. 141

35 Sterols continued Foods- found naturally-cholesterol vs phytosterol Function Membranes Lipoproteins Bile acids Hormones Vitamin D

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38 Fatty acids in foods regardless of free or esterified Function of fatty acids in food essential in diet- linoleic acid and alpha-linolenic acid-we cannot make these

39 Ingestion- mouth, tube or IV Digestion of lipids p fats start out separated from enzymes in gi (gastrointestinal tract)-why?\ goal of fat digestion mouth digestion of fat small intestine digestion of fat

40 Absorption of lipids p small molecules short chain fatty acids medium chain fatty acids glycerol direct to blood larger molecules monoglycerides long chain fatty acids micelles formed in intestine micelles into intestinal wall cells chylomicrons formed and released into lymph E:\Media\Animations\chapter5\Absorption_of_Fat\051 7.html

41 Transport of lipids p Lipoproteins-chylomicrons (CM) (POST-PRANDIAL ONLY) - very low density lipoprotein (VLDL) - low density lipoprotein (LDL) - high density lipoprotein (HDL) - albumin density change due to 2 factors

42 Lipoprotein metabolism Chylomicrons- made in small intestine – acted on by lipoprotein lipase in blood to give remnant particle which is taken up liver VLDL (very low density lipoprotein) made via liver VLDL acted on by lipoprotein lipase in blood to give remnant particle (intermediate density lipoprotein or IDL) which is taken up by liver- liver puts out low density lipoprotein (LDL) HDL ( high density lipoprotein) and albumin made by liver

43 Human lipid metabolism-in part only Fatty acids oxidised in mitochondria to give energy and water Glycerol metabolised (enters glycolytic path and then mitochondria) Can also synthesise fatty acids, triglycerides, phospholipids and sterols

44 Lipids excretion Faeces-undigested and/or unabsorbed fat Respiration (lipid metabolites -water and CO 2 ) Urine-lipid metabolite (water) Sweat-lipid metabolite (water) Saliva?-intact fats and lipid metabolite (water)

45 Lipids essential or not ? p Yes-why ? healthy roles

46 Lipids- essential or not? yes- healthy roles 1)insulation- healthy roles protective layer in body to help keep heat losses down

47 Lipids-essential or not? yes Healthy roles 2)support and protection for internal organs and bones fat acts as support and cushioning for organs and cushioning for bones

48 Lipids- essential or not? yes Healthy roles 3)absorption of fat soluble vitamins fat soluble vitamins cannot be absorbed without fat in the diet- why?

49 Lipids- essential or not? yes Healthy roles 4)cell membranes cholesterol and phospholipids are important in maintaining the structure and hence function of cell membranes what is a cell membrane?

50 Lipids- essential or not? yes Healthy roles 5) gives structure to molecules fatty acids give rise to triglycerides and phospholipids and cholesterol fatty acid complexes structure of lipids in part dictates their function

51 Lipids- essential or not? yes Healthy roles 6)metabolically -fat stored as fat- very efficient -making fat from carbohydrate and protein is not very efficient -energy source-can store huge quanities of fat

52 Lipids- essential or not? yes Healthy roles 7) impact on nutrient absorption -gut motility is slowed -slower rate of digestion

53 Fats - Unhealthy roles Fad diets no fat or less than 10 % of calories as lipid in diet with all or mostly all of energy difference made up with carbohydrate

54 Fat- Unhealthy roles Fat to fat- obesity -obesity- tough on joints, -may contribute to arthritis -elevates blood pressure- which may give atherosclerosis and heart attacks and stroke

55 Fat- Unhealthy roles Unhealthy roles-obesity continued -elevates free fatty acids in the blood which may give insulin resistance -if excess fat in the diet this may crowd out other nutrient classes