UGRC 145: FOOD AND NUTRITION IN EVERYDAY LIFE Session 2 MACRONUTRIENTS Lecturer: PROF. MATILDA STEINER-ASIEDU, SBS, CBAS; University of Ghana, Email: tillysteiner@gmail.com College of Education School of Continuing and Distance Education 2014/2015 2016/2017
Session Overview At the end of this lecture you should be able to 1. List the macronutrients 2. List the food sources for each macronutrients 3. Describe the functions of each macronutrients 4. Explain problems associated with excess intake and deficiency Prof M. Steiner-Asiedu Slide 2
Session Outline The key topics to be covered in the session are as follows: Topic One: Types of Macronutrients? Topic Two: Carbohydrate Topic Three: Protein Topic Four: Fat Topic Five: Assignment/Discussion For Next Session Prof M. Steiner-Asiedu Slide 3
Topic One TYPES OF MACRONUTRIENTS Prof M. Steiner-Asiedu Slide 4
What are the macronutrients? Main energy providers for the body Three groups: 1. Carbohydrate : One gram=4 Calories (kcal) 2. Protein One gram = 4 Calories (kcal) 3. Fat One gram fat = 9 Calories (kcal) Prof M. Steiner-Asiedu Slide 5
Topic Two CARBOHYDRATE Prof M. Steiner-Asiedu Slide 6
What are carbohydrates? Hydrates (water) of carbon Contains carbon, hydrogen and oxygen Carbohydrates: formed from plants via photosynthesis Glucose sun Chlorophyll Water Carbon dioxide Oxygen Prof M. Steiner-Asiedu Slide 7
Types of carbohydrates Three types: Simple carbohydrates Complex carbohydrates Dietary fibre Prof M. Steiner-Asiedu Slide 8
Simple carbohydrates Have one or two units of sugar One sugar unit - simple sugar (monosaccharide) Examples: Fruit sugar (fructose) Blood sugar (glucose) Two sugar units - double sugar (disaccharide) Example: sucrose (table sugar) Prof M. Steiner-Asiedu Slide 9
Complex carbohydrate More than two units of sugar joined togetherpolysaccharides Complex carbohydrates with 3 to 10 units of sugar are sometimes called oligosaccharides Prof M. Steiner-Asiedu Slide 10
Dietary fibre Term used to distinguish fibre found in foods from those found in synthetic and natural materials Dietary fibre characteristics Polysaccharide Bonds between sugars cannot be broken down by the human digestive enzymes Prof M. Steiner-Asiedu Slide 11
Dietary fibre cont d Grouped into two 1. Those that are soluble in water and a termed soluble fibre 2. Those that are not soluble in water and a termed insoluble fibre Prof M. Steiner-Asiedu Slide 12
Characteristics of Insoluble fibre Natural laxative Absorbs water Helps you feel full when eating Prevents constipation Examples: Cellulose from kontomire Beans Whole maize Millet Sorghum local rice Prof M. Steiner-Asiedu Slide 13
Characteristics of soluble fibre Potential to lower blood cholesterol Examples: Oats Citrus fruits (Oranges, grapefruits, tangerine) Prof M. Steiner-Asiedu Slide 14
Functions of carbohydrates 1. Providing energy 2. Protect muscles Carbohydrates are the first port of call for energy If none is available, then the body uses muscles Carbohydrate diet is sometimes referred to as protein sparing 3. Lower blood cholesterol levels and regulate blood pressure - dietary fibre Prof M. Steiner-Asiedu Slide 15
Topic Three PROTEIN Prof M. Steiner-Asiedu Slide 16
Protein Essential nutrient (Greek word protos, which means first ) Protein molecule -long chain of amino acids Amino acids - building blocks of protein Prof M. Steiner-Asiedu Slide 17
Proteins There are 20 different amino acids; the basic units of proteins Nine are essential amino acids Rest are non-essential Prof M. Steiner-Asiedu Slide 18
What are essential amino acids? These are amino acids that must be present in the food or diet that an individual eats. The human body cannot make the essential amino acids. Examples are: Lysine Tryptophane Methionine Prof M. Steiner-Asiedu Slide 19
Functions of proteins 1. Enzymes - speed chemical reactions (catalysts) 2. Antibodies - Proteins that help fight illness and disease 3. Haemoglobin - Protein found in the blood that transports oxygen all over the body 4. Hormones (most) - Proteins that regulate many body functions 5. Growth - building materials 6. Maintenance - repair of body tissues Prof M. Steiner-Asiedu Slide 20
Protein types All proteins are NOT considered equal Not all proteins contain all the amino acids needed by the body Proteins are grouped into two based on the amino acids profile Complete Incomplete Prof M. Steiner-Asiedu Slide 21
Complete proteins Complete proteins: Contain ample amounts of essential amino acids. Animal proteins (meat, fish, eggs and poultry) are considered good sources Prof M. Steiner-Asiedu Slide 22
Incomplete proteins Incomplete proteins Do not have enough of one or more of the essential amino acids Plant proteins (grains, legumes, nuts, seeds and other vegetables) are incomplete proteins Prof M. Steiner-Asiedu Slide 23
Complementary proteins Good quality protein from plant sources Combine foods from the various plant sources to balance each other Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids Prof M. Steiner-Asiedu Slide 24
Table 1: Foods that complement each other to form complementary proteins Prof M. Steiner-Asiedu Slide 25
Problems with eating to much or too little protein Overeating protein is not a major problem in Ghana Not eating enough protein is however a major problem especially in children When children do not get enough protein, they may develop a disease called Kwashiorkor Marasmus occurs when children do not get enough protein and energy Prof M. Steiner-Asiedu Slide 26
Protein energy malnutrition KWASHIOKOR Prof M. Steiner-Asiedu Slide 27 MARASMUS
Topic Four FAT Prof M. Steiner-Asiedu Slide 28
Fats The chemical family name for fat and related compounds is Lipids Fat = Liquid (oil) or solid Fat energy value = 9 Calories Energy values of fat is higher than Protein or carbohydrate = 4 calories Alcohol = 7 Calories Prof M. Steiner-Asiedu Slide 29
Types of fats Foods contain three kinds of fats: 1. Triglycerides 2. Phospholipids 3. Sterols. Prof M. Steiner-Asiedu Slide 30
Structure of common fat - Triglycerides Glycerol, a small, water-soluble carbohydrate derivative, plus three fatty acids equals a triglyceride R + R Glycerol R 3 Fatty acids of differing lengths A fat or oil (a triacylglycerol Prof M. Steiner-Asiedu Slide 31
Classification of Fat 1. Saturated fatty acids (SFA) contain the maximum amount of hydrogen atoms possible all C-C bonds are single SFA tend to be solid at room temperature 2. Monounsaturated fatty acids (MUFA) have 1 point of unsaturation MUFA tend to be solid at refrigerator temperature 3. Polyunsaturated fatty acids (PUFA) have 2 or more points of unsaturation PUFA are liquid at room and refrigerator temperatures Prof M. Steiner-Asiedu Slide 32
Classification of Fat Cont d Prof M. Steiner-Asiedu Slide 33
Composition of fatty acids in common fats and oils Prof M. Steiner-Asiedu Slide 34
Trans fatty acids Trans fatty acid occurs during hydrogenation Process of changing plant oils into fats that resemble animal fat by the addition of hydrogen Can be harmful because they act as saturated fats Prof M. Steiner-Asiedu Slide 35
Functions of fats 1. The body stores energy as fat 2. Acts as insulation blanket that reduces heat loss 3. Part of every cell membrane & covers nerves 4. A shock absorber that protects internal organs from injury and shocks 5. Used in formation of hormones (vitamin D) 6. Use in the formation of bile 7. Aid the transport of fat soluble vitamins Prof M. Steiner-Asiedu Slide 36
Topic five ASSIGNMENT/DISCUSSION FOR NEXT SESSION Prof M. Steiner-Asiedu Slide 37
Take Home What is the energy value of a meal containing 20 grams fat, 50 grams protein and 200 grams carbohydrate? Prof M. Steiner-Asiedu Slide 38
NEXT WEEK We shall discuss Micronutrients Make sure you read the section in handout 2A before class. Prof M. Steiner-Asiedu Slide 39