A3 Nutrition, balanced diet and health. Protein. Use your glossary to define the following terms: protein. amino acid. essential.

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1 Sha Tin College IB Design and Technology A3 Nutrition, balanced diet and health Protein Use your glossary to define the following terms: protein amino acid essential Biological value The Nutritional Function of Protein Protein has many important functions as a nutrient: It is necessary for the growth and repair of body tissues. It is also a source of energy. 1g of protein provides 17kJ (4 kcal) Essential and non essential amino acids After a protein is eaten it is broken down by digestion into amino acids, which are then absorbed and used to make other proteins in the body. The human body is able to make some amino acids for itself. These are known as non-essential (or dispensible) amino acids. However, it is not able to do this for every amino acid so a certain number must be supplied by the diet. They are known as the essential (or indispensable) amino acids and for the human adult there are eight: Isoleucine Leucine Lysine Methionine Phenylalanine Threonine, Tryptophan Valine In children, Histidine is also considered to be an essential amino acid since they are unable to make enough to meet their needs. Animal and plant-source proteins All animal and plant cells contain some protein but the amount of protein present in food varies widely (Figure 4). It is not just the amount of protein that needs to be considered - the quality of the protein is also important and that depends on the amino acids that are present. If a protein contains the essential amino acids in the approximate proportion required by humans, it is said to have a high biological value. If it is 1

2 comparatively low in one or more of the essential amino acids it is said to have a low biological value. The amino acid that is in shortest supply in relation to need is termed the limiting amino acid. In general, proteins from animal sources have a higher biological value than proteins from plant sources, but the limiting amino acid varies. Lysine is the limiting amino acid in wheat protein, Tryptophan in maize protein, and Methionine and Cysteine in beef protein. Among the vegetable sources, soya protein is the most complete. Figure 4 Protein content of a selected number of foods (g/100g food) Food Amount of protein (g per 100g of food) White rice, cooked 2.6 Pasta, cooked 7.7 White bread 7.9 Semi-skimmed milk 3.4 Cheddar cheese 25.4 Poached egg 12.5 Rump steak, grilled 31.0 Peanuts 25.6 TASK - Complete the chart with examples of HBV and LBV proteins HBV Protein Foods LBV Protein Foods 2

3 Complementary action of proteins The limiting amino acid tends to be different in different proteins, so when two foods providing vegetable protein are eaten at a meal, such as a cereal (e.g. bread) and a pulse (e.g. baked beans), the amino acids of one protein may compensate for the limitations of the other, resulting in a combination of higher biological value. This is known as the complementary action of proteins. Amino acid histograms for cheese and bread protein The effect of low protein intake - protein deficiency Protein energy malnutrition (PEM) describes a range of disorders occurring mainly in developing countries. It mainly affects young children and is the result of both too little energy and too little protein in the diet. The two most common forms of PEM are marasmus and kwashiorkor. 1. Marasmus occurs in infants under one year of age who have been weaned off breast milk onto a diet containing too little energy and protein. In addition, inadequate hygiene often leads to contamination of foods which causes infections, particularly gastro-intestinal infections, and a further increase in energy requirements. The parent may treat this by fasting the child, giving only water or other fluids of little nutritional value. As a result, the child becomes severely underweight and very weak and lethargic. 2, Kwashiorkor tends to occur in slightly older children who, after an extended period of breast feeding, have been weaned onto a diet high in starchy foods which is low in energy and protein. Kwashiorkor often follows an acute infection. A child with kwashiorkor is severely underweight but this is often masked by oedema (water retention) which makes the face moon-shaped, and the arms and legs look plump. The hair is thin and discoloured, and the skin may show patches of scaliness and variable pigmentation. Medical treatment and an adequate diet, combined with good hygiene practices, are vital if children with PEM are to recover and grow properly. 3

4 Questions 1. State THREE functions of protein? 2. Explain the terms essential and non essential amino acids. 3. Outline why the biological value of protein significant? 4. Describe using examples how the problem of a limiting amino acid be avoided? 5. List six good sources of protein. Practical Task Make a food product which contains a high biological value protein. State the target group for the food product. Calculate the protein content of the food product and compare this to the needs of your target group. Prepare a time plan and an order form (the order form for ingredients from school). 4

5 Key points Protein is needed for growth and repair of the body. The building blocks of protein are called amino acids. Proteins are made of amino acids joined together to form chains. Foods contain essential and non essential amino acids. High biological value proteins contain all the essential amino acids needed by the body. Protein can also provide energy: 1 gram provides 17 kj (4 kcal). Carbohydrate Use your glossary to define the following terms: Monosaccharide Disaccharide Polysaccharide Use pages 102 and 103 of Burnett-Fell and Stutchbury Food Technology in Action to answer the following questions. Your teacher will give you additional information for question State the names of THREE monosaccharides. Outline the source of these monosaccharide. Name of monosaccharide Source 5

6 2. Complete the spaces to show which two molecules are combined together to make the following disaccharides: Sucrose is one molecule of and one molecule of Lactose is one molecule of and one molecule of Maltose is one molecule of and one molecule of 3. Outline the source of these disaccharides. Name of disaccharide Source Sucrose Lactose Maltose 4. State the names of FOUR polysaccharides. Outline the source of these polysaccharides. Name of polysaccharide Source 6

7 The Nutritional Function of Carbohydrate Carbohydrate provides energy 1g of carbohydrate provides 16kJ (4 kcal) During digestion sugars and starches (carbohydrates) are broken down to glucose. Glucose is also stored as glycogen stores and when dietary supply of glucose is unable to supply the demands of the body, the glycogen is converted back to glucose. Glucose is transported via the bloodstream to ceslls and there energy release occurs. (NOTE remember amino acids from protein can also provide energy when other sources have been used). Total Carbohydrate, Sugar and Starch Content of Foods Use food tables to complete the sugar and starch content of these foods: Sugar Rice Pasta Potato (boiled) Biscuits Honey Jam Apple Milk (whole) Chocolate Carrots Cornflakes Percentage Carbohydrate Percentage Sugars Percentage Starch TASK - Product Analysis Product 1: Product 2: Product 3: Look at the ingredients lists found on the products food label. 7

8 Complete the information for these products Product name and ingredients Does this ingredient contain carbohydrate? Type of carbohydrate 8

9 Staple Foods Staple foods are defined as foods that are commonly eaten as part of a daily diet. To be classed as a staple the food must provide energy, be cheap and readily available. Cassava, rice, wheat, potatoes and maize (corn) are staple foods eaten in different parts of the world. Use page 4 of Burnett-Fell and Stutchbury Food Technology in Action to complete plant sources of staple foods around the world. The Effect of Low and Excess Carbohydrate Intakes Lipids Table of Important Lipid Definitions Term Lipid Glycerol Definition An organic compound that contains aliphatic hydrocarbons, essential for the structure and function of living cells. Examples include fats, waxes and steroids. A sugar alcohol with three hydrophilic hydroxyl groups. It is an important component of triglycerides (fats and oils) and phospholipids. 9

10 Triglyceride Fatty acid Essential fatty acid Saturated fatty acid Unsaturated fatty acid Fatty acids are carboxylic acids with a long hydrocarbon chain, usually straight. Fatty acids that are required in the human diet. This means that they cannot be synthesized by the body from other fatty acids and must be obtained from food. A fatty acid in which no double bonds are present between the carbons of the fatty acid chains. One in which there are double bonds present between the carbons of the fatty acid chains. Look up the following link: onid=320&parentsection=299&which=1 The Nutritional Function of Lipids Lipids many important functions as a nutrient: Lipids are a rich source of energy 1g of carbohydrate provides 37kJ (9 kcal) An insulating layer under the skin Protecting vital internal organs Fats act as a carrier for fat soluble vitamins A, D, E and K. Lipids prevent hair and skin becoming too dry Lipids provide essential fatty acids. 10

11 The Main Sources of Lipids in the Diet The pie chart shows the main source of fat in the diet of British adults. How do you think these figures compare to adults in: a) Hong Kong b) Japan c) North America The Effect of Low and Excess Fat Intakes Lipids contribute to the feeling of fullness (satiety) and the body digests them slowly..as already stated lipids are a very rich source of energy. When dietary fat exceeds the body s requirement, the excess fat is stored in the body as adipose tissue. This is found under the skin and surrounding vital organs. Fat is a concentrated source of energy and foods that are high in fat provide a lot of energy. As fat provides a feeling of satiety it is easy to consume an fat and therefore an excess of energy. If too much energy is consumed, the excess energy is stored in the body as fat. Over the long term this may result a person becoming overweight or obese. Obesity is defined as an excessively high amount of body fat in relation to lean body mass. A body mass index of more than 30 is defined as obese by the World Health Organization. Vitamins and Minerals Vitamins - Organic molecules required by a living organism in minute amounts, but which the organism cannot synthesize. Minerals - Natural compounds formed through geological processes. Water Soluble Vitamins 11

12 Use pages 109 to 111 of Burnett-Fell and Stutchbury Food Technology in Action to complete the following chart. Vitamin Function Sources Effects of deficiency or excess intake Vitamin C Thiamin B1 Riboflavin B2 Niacin Pyridoxide Pantothenic acid Folate 12

13 Vitamin B12 Fat Soluble Vitamins Use pages 108 to 109 of Burnett-Fell and Stutchbury Food Technology in Action to complete the following chart. Vitamin Function Sources Effects of deficiency or excess intake Vitamin A Vitamin D Vitamin E Vitamin K Minerals Use pages 112 to 114 of Burnett-Fell and Stutchbury Food Technology in Action to complete the following chart. 13

14 Minerals Function Sources Effects of deficiency or excess intake Calcium Phosphorus Iron Sodium and potassium Zinc Fluorine 14

15 Vitamins and Minerals Practical Task Date of practical: 1. Choose a food product. 2. Calculate the nutritional value of one serving of the product. 3. Identify one vitamin OR one mineral to increase e.g. increase the calcium content of a salad increase the iron content of a muffin increase the vitamin D content of fried rice 4. Modify the recipe to improve the nutritional value of the chosen vitamins OR minerals. 5. Recalculate the nutritional value and compare with the control. 6. Prepare a ingredient list, equipment list and time-plan 7. Prepare an ingredient order form. Vitamins and Minerals Key points Vitamins and minerals are micronutrients they are needed in very small amounts. Vitamins and minerals have many roles in the body. The body s requirement for vitamins and minerals changes during our lifetime. Balanced Diets and Health Micronutrient deficiency Malnutrition Lack of essential vitamins and minerals resulting from unbalanced food intake and specific problems of food absorption. The physiological condition resulting from inadequacy or imbalance in food intake or from poor absorption of food consumed. What is meant by a balanced diet? In order to help consumers understand what constitutes a balanced diet and therefore to achieve a healthy nutritious diet various food selection guides have been developed. They aim to show consumers in an easy to understand how appropriate food choices. Read pages 128 to 130 of Burnett-Fell and Stutchbury Food Technology in Action to find out more about food selection guides. 15

16 Read the information on the following link 16

17 Look at the nutritional education diagrams and analysis their effectiveness using the following chart Nutritional Education Diagram Produc ed by Advantages Disadvantages Effectiv e? Nutritional Requirements and Food Choice during the Lifecycle Age, body size and gender affect the amount of energy and nutrients an individual needs during various stages of the lifecycle. Energy Requirements The minimum amount of energy required by the body is referred to as the basal metabolic rate (BMR). This differs from individual to individual and is a calculation of the amount of energy required to maintain all essential processes whilst the body is at rest. Explain how the following factors influence basal metabolic rate: 1. Age 2. Physical activity 3. Size 17

18 4. Amount of lean tissue 5. Gender 6. Physical state Use the following link to find out more about nutritional needs: ng.htm RESEARCH TASK Research the nutritional requirements of ONE of the following groups. Chapter 7 Diets for Optimum Nutrition of Burnett-Fell and Stutchbury Food Technology in Action is a good starting point to find out more about the nutritional requirements of: Pregnancy and lactation Infancy Adolescence Elderly people Balanced diets revision Watch the DVD Designing Menus for Balanced Diets Answer the following questions as you watch. 1. Outline what the body needs to function? 18

19 2. State the name of the most basic nutrient. 3. List the 5 nutrients and name an example of a food, which contains each one. Nutrient Food 4. Describe what happens to children who don t get enough protein in their diet. 5. In order to have a balanced diet identify the percentage of energy which should come from the following: a) Protein b) Carbohydrate c) Fat 6. Explain the function of iron in the body? 7. Define the medical condition is Osteoporosis? 8. Outline the proportions of foods recommended in the Healthy Diet Pyramid, to promote a balanced diet. 8. Explain the term lacto-ovo vegetarian? 9. Identify the non-meat foods which are good sources of iron? 19

20 11. Explain how can vegetarians can increase their absorption of iron? The Nutritional Content of Typical Foods Changing Diets The change in diets from a traditional diet based on staple foods in many countries is having an impact on health. Obesity, coronary heart disease (CHD), cancers and diabetes are on the increase. Discuss the social impacts of the increasing incidence of these diseases. A3Nutrition, balanced diet and health 6 hours Assessment statement Obj Teacher s notes Proteins (1 hour) A.3.1 Define protein, amino acid, essential and biological value. 1 A.3.2 Describe the role of protein in the body. 2 Protein provides essential and non-essential amino acids and acts as an energy source. A.3.3 A.3.4 Identify foods of high biological value and low biological value. Describe how low biological value foods are complemented in different parts of the world to ensure that essential amino acid requirements are met. 2 2 For example, complementation of rice and beans. A.3.5 Discuss the effect of low protein intake. 3 Stunted growth, kwashiorkor, marasmus. Carbohydrates (1 hour) A.3.6 A.3.7 A.3.8 A.3.9 A.3.10 Define monosaccharide, disaccharide and polysaccharide. Describe the role of carbohydrate as an energy source in the body. Identify the importance of staple foods in the provision of dietary carbohydrate. Explain that carbohydrate foods are often cheap and used by people on low incomes to bulk their diet. Discuss the effects of low and excess carbohydrate intakes For example, cassava, rice, wheat, maize, potatoes and sugar. 3 3 Lipids (1 hour) A.3.11 Define lipid, glycerol, fatty acid, essential fatty acid, saturated fatty acid and unsaturated fatty acid. 1 A.3.12 Describe the role of lipids in the body. 2 20

21 A.3.13 Identify major sources of lipids in the diet. 2 A.3.14 Discuss the effects of low and excess lipid intakes. 3 Vitamins and minerals (1 hour) A.3.15 Define vitamins and minerals. 1 A.3.16 Describe the role of water-soluble vitamins (vitamin B complex, vitamin C) in the body and their food sources. 2 A.3.17 Describe the role of fat-soluble vitamins (vitamins A, D, E, K) in the body and their food sources. 2 A.3.18 A.3.19 Describe the effects of deficiency of water-soluble vitamins on the body. Describe the effects of deficiency or excess of fatsoluble vitamin intake. 2 For example, effect of lack of B vitamins or vitamin C. 2 For example, cases of excess vitamin A or D intake in children in western Europe, and effect of lack of vitamin A on eyesight in parts of central Africa. A.3.20 Describe the functions and sources of minerals. 2 Consider calcium and iron. A.3.21 Discuss the effect of low or excessive intake of calcium and iron. 3 Balanced diets and health (2 hours) A.3.22 Define micronutrient deficiency and malnutrition. 1 A.3.23 A.3.24 Explain what is meant by a balanced diet and how various food-group systems can be used to help achieve a balanced diet. Explain how nutritional requirements and food choice change as a person gets older. 3 Consider pyramid, chalice, five a day and plate systems. 3 A.3.25 Identify the nutrient content of typical foods. 2 A.3.26 A.3.27 Discuss how health awareness affects food choice with reference to fat (quality and quantity), fibre, sugar and salt content. Discuss the social impacts resulting from a change from traditional diets and the effect on consumer health. 3 Consumer awareness of acute and chronic health issues has a major impact through the food chain from food production to food manufacture and distribution. Understanding of such issues and health impacts has a considerable influence on patterns of food consumption. 3 Consider the increasing incidence of diabetes and obesity. 21