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Chapter 5 O PR O PA G E As health status has improved over time and life expectancy has increased, behavioural factors have had more time to affect the health of individuals. One significant behavioural determinant that affects health is nutrition. Poor nutrition is linked to a number of health conditions including cardiovascular disease, diabetes mellitus, colorectal cancer, obesity and osteoporosis. These conditions contribute to a large number of premature deaths and significant levels of morbidity in Australia. Having an understanding of the role of key nutrients in the protection or development of these conditions is essential to enable a range of interventions to be developed and further improvements in health to be made. FS Nutrition and the NHPAs EC TE D KEY KNOWLEDGE 1.6The role of nutrition in addressing the following conditions recognised in the NHPAs: cardiovascular disease, diabetes mellitus, colorectal cancer, obesity and osteoporosis, taking into account, where relevant, the function (as a determinant of health) and major food sources of protein, carbohydrate (including fibre), fats (mono, poly, saturated and trans), water, calcium, phosphorus, sodium and vitamin D (pages 00–00) U N C O R R KEY SKILL • Explain the role of nutrition in addressing specific conditions within the NHPAs, including the functions and major food sources of relevant nutrients (pages 00, 00, 00, 00). 212 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 212 11 June 2015 7:57 PM KEY TERM DEFINITIONS U N C O R R EC TE D PA G E PR O O FS bile a chemical released into the intestines to assist in the absorption of dietary fat bone matrix the structure of bone that allows calcium and phosphorus to be deposited, therefore making the tissue hard. The bone matrix consists mainly of collagen digestive tract a collection of organs that carry out digestion. The organs are the mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus energy-dense foods foods that contain significant amounts of fat, therefore contributing large amounts of energy to the diet fortified (foods) foods that have particular nutrients added to them during processing heart failure a condition characterised by the heart’s inability to supply sufficient blood flow to body cells and tissues indigestible cannot be absorbed by the body intracellular fluid fluid between the cells legume a type of pod. Examples include alfalfa, peas, beans, lentils and peanuts macronutrients nutrients that are required in large amounts, such as protein, carbohydrates and fats metabolism refers to all of the chemical processes occurring in the body. Metabolism includes the processes that take place to break food down into its most basic components and the processes that turn these components into energy or body cells micronutrients nutrients that are required in small amounts, such as vitamins and minerals nutrient a substance that is used by living things to build tissue or provide energy in order to assist in growth or to keep the organism alive ossification the process whereby bones are hardened by laying down the minerals calcium and phosphorus peak bone mass the highest level of bone mass reached throughout the life span (usually attained in the late 20s or early 30s) protective nutrient any nutrient that acts to protect a person from a certain condition risk nutrient any nutrient that increases the chances of developing a certain condition c05NutritionAndTheNHPAs.indd 213 11 June 2015 7:57 PM 5.1 The nutrients and the NHPAs: Carbohydrates (including fibre) and protein KEY CONCEPT Understanding the role that nutrients play in addressing health conditions identified within the NHPAs: carbohydrates (including fibre) and protein FS Nutrition is one of the key behavioural determinants of health in Australia. It can act to decrease or increase the risk of a range of conditions identified within the NHPAs, including cardiovascular health, diabetes mellitus, colorectal cancer, obesity and osteoporosis. With issues such as increasing rates of obesity and type 2 diabetes in Australia, it is important to examine the nutrients found in food to gain an understanding of how nutrition can be used to improve health status and address the conditions within the NHPAs. Having a balanced food intake with plenty of variety is the key to maintaining an adequate diet and therefore reducing the risk of diet-related conditions. Six categories of nutrients are needed for optimal health. They are: • carbohydrates (including fibre) • protein • fats • vitamins • minerals • water. Carbohydrates, protein and fats are collectively termed macronutrients, and vitamins and minerals are known as micronutrients. Water is not technically a nutrient, so it is not classified in either group. However, large quantities of water are required for optimal health. There are many different nutrients required by the body for good health. The main nutrients that play a risk or protective role in relation to the NHPAs are summarised in figure 5.1. Each nutrient plays a different role and is required in different amounts, but all are important for good health. Unit 3 O AOS 1 See more Carbohydrate Topic 8 All nutrients R R EC TE D PA G E PR O Concept 2 O Carbohydrates (including fibre) Fats Minerals Vitamins Water U N C Protein Monounsaturated Polyunsaturated Saturated Trans Vitamin D Calcium Phosphorus Sodium FIgURE 5.1 Numerous nutrients can increase or decrease the risk of conditions identified within the NHPAs. Carbohydrates Carbohydrates are considered a macronutrient as we tend to need relatively large quantities each day. The main function of carbohydrates is to provide fuel for energy. When food is eaten, the body metabolises the carbohydrates in the food into useful glucose molecules, the most basic form of carbohydrate. Glucose molecules are 214 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 214 11 June 2015 7:57 PM O FS then used for energy production. In terms of energy production, one gram of carbohydrate produces 16 kilojoules of energy. Glucose molecules (and therefore carbohydrates) not used by the body for energy are stored as adipose (or fat) tissue. This process can be reversed if glucose is needed by the body. For example, in times of starvation, fatty tissue can be broken down and converted back into glucose to be used for energy. If continually eaten in excess, carbohydrates can contribute to obesity and related conditions such as cardiovascular disease, diabetes mellitus (particularly type 2 and gestational) and colorectal cancer. PR O Sources of carbohydrates Figure 5.2 Carbohydrates are used as a fuel for energy production. If not used for energy, excess carbohydrates are stored as fat, which can contribute to weight gain. EC TE D PA G E Carbohydrates are found in foods of plant origin. Different foods contain varying amounts of carbohydrates and therefore varying amounts of energy. Care should be taken to ensure that the foods selected do not contain unnecessarily high levels of energy. For example, foods containing high levels of sugar, such as soft drinks, are rich in carbohydrates, but they often contain more energy than is required by the individual and usually contain low levels of other nutrients. Major food sources of carbohydrates include: • fruits such as oranges, grapes and bananas • starchy vegetables such as potatoes and parsnips • corn • beans • pasta • bread • rice • breakfast cereals such as wheat biscuits and bran. Fibre U N C O R R The main function of fibre is to regulate the functioning of the digestive system. Adequate fibre intake prevents constipation by adding bulk to faeces and assists in removing waste products through the digestive tract. Technically a type of carbohydrate, fibre is made up of the indigestible parts of plant matter found in cereals, vegetables and fruits. Foods that are high in fibre, particularly fruit and vegetables, are usually rich in vitamins and minerals and low in fat, which can improve health and reduce the risk of a number of NHPA conditions, including: • colorectal cancer. Although the relationship between fibre intake and the development of colorectal cancer is still unclear, societies that eat high-fibre diets have much lower rates of colorectal cancer • obesity. By providing a feeling of fullness without the kilojoules, a food intake high in fibre can reduce the amount of energy consumed from other foods • diabetes mellitus (type 2 and gestational). Fibre has been shown to reduce the absorption of glucose from the small intestine. This can decrease the risk of obesity and associated conditions such as diabetes mellitus Figure 5.3 Fibre is essential for the health of the digestive system and can decrease the risk of colorectal cancer. Nutrition and the NHPAs • CHAPTER 5 215 c05NutritionAndTheNHPAs.indd 215 11 June 2015 7:57 PM 5.1 The nutrients and the NHPAs: Carbohydrates (including fibre) and protein FS • cardiovascular disease. Fibre reduces blood cholesterol levels by binding to bile. Bile is released into the stomach to assist in the digestion of dietary fat. Once the fat is digested, bile is normally reabsorbed into the blood stream. Fibre binds with bile and excretes it, preventing it from being reabsorbed. The liver makes more bile to replace what has been excreted. Cholesterol is a key component of bile, so bile production reduces the amount of cholesterol in the blood. Foods high in fibre generally have lower saturated fat content, which further reduces the production of cholesterol. Sources of fibre PR O O The Australian Heart Foundation recommends that adults eat between 25 and 30 grams of fibre every day. Children should consume 10 grams plus one gram for every year of age (for example, 20 grams for a ten-year-old). Examples of foods that contain fibre are: • bran flake cereal • wholemeal bread • fruit and vegetables — particularly good sources include raspberries, apples, bananas, pears, oranges, peas, potatoes, broccoli and corn • baked beans. Fibre absorbs water, so if the amount of fibre in the diet is increased, water consumption should also be increased. Protein PA G E Figure 5.4 Bran, which is found in many breakfast cereals, is a good source of fibre. Unfortunately, too few people get enough of this nutrient. O R R EC TE D Protein is considered a macronutrient. The primary function of protein is to promote the growth, maintenance and repair of body cells. However, as a secondary function, protein is also used as a fuel for energy production. This means that if there are insufficient carbohydrates and fat for energy use, protein may be used. Protein that has been converted into muscle and other tissues can also be used as a fuel source during times of starvation. Protein yields approximately 17 kilojoules per gram when used for energy. Although protein deficiency is rare in Australia, a World Health Organization report (2003) suggests that protein deficiency may contribute to decreased bone density and an increased risk of osteoporosis. According to the Australian Institute of Sport (2014), excess protein may be converted into glucose and then stored as fat if not used for growth, repair or energy. As a result, excess protein intake can contribute to obesity and related NHPA conditions such as cardiovascular disease, diabetes mellitus (specifically type 2 and gestational diabetes) and colorectal cancer. Although most people in Australia have enough protein in their diet, some people supplement their dietary protein with products such as protein shakes in an attempt to build muscle. According to the Better Health Channel, people taking supplementary protein while weight training add no more muscle than those not taking protein supplements. Excess protein intake can put strain on the kidneys and liver, which are responsible for protein metabolism. Excess protein may also lead to excessive loss of the mineral calcium from bones, which can contribute to osteoporosis. U N C Figure 5.5 Nuts, grains, lean meat, fish and eggs are rich sources of protein. 216 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 216 11 June 2015 7:57 PM Sources of protein Unit 3 AOS 1 Topic 8 See more Protein O FS Concept 1 Unit 3 AOS 1 Topic 8 Concept 1 Do more Protein R EC TE D PA G E PR O Although found in vast amounts in animal products, protein can also be found in many foods of plant origin. Some rich sources of protein include: • animal origin: –– eggs –– milk, cheese and other dairy products (except cream) –– beef –– chicken and other poultry –– fish and seafood. • plant origin: –– soy products (such as tofu and soya milk) –– legumes –– nuts –– whole grain cereals –– brown rice. Care should also be taken when choosing protein-rich foods, as some options are healthier than others. For example, steak is a good source of protein, but if it is not a lean cut (that is, if it has a lot of fat around and through it), the benefits of getting the protein from the meat may be outweighed by the extra fat that is being consumed. Much of the fat from red meat is saturated fat, which has further negative health implications. Fish, such as salmon, is a better option as it is rich in protein but has half the fat of a normal steak, and only a small percentage is saturated fat. Lentils are another good source of protein, with very low levels of fat and high levels of fibre. R TEST your knowledge U N C O 1 What are the six categories of nutrients? 2 Explain what is meant by the term: (a)macronutrient (b)micronutrient (c)metabolism. 3 (a) What is the main function of carbohydrates? (b) How much energy does one gram of carbohydrate produce? 4 (a) What is the function of fibre? (b) List five foods that are major sources of fibre. 5 (a) Outline the functions of protein. (b) How much energy does one gram of protein provide? (c) List four food sources of protein. APPLY your knowledge 6 Explain the possible positive or negative health impacts of consuming a diet high in the following nutrients over a period of time. (a)Carbohydrates (b)Fibre (c)Protein 7 Outline the possible health impacts of consuming diets low in the following nutrients over a period of time. (a)Fibre (b)Protein 8 Identify and explain any relationships that exist between obesity, cardiovascular disease, diabetes mellitus, colorectal cancer, osteoporosis and: (a) carbohydrates (including fibre) (b)protein. 9 Approximately how much fibre should the following people consume each day? (a) Fletcher, a 7-year-old male (b) Laura, a 15-year-old female (c) Lisa, a 22-year-old female Nutrition and the NHPAs • CHAPTER 5 217 c05NutritionAndTheNHPAs.indd 217 11 June 2015 7:57 PM 5.2 The nutrients and the NHPAs: Fats and water KEY CONCEPT Understanding the role that nutrients play in addressing health conditions identified within the NHPAs: fats and water Fats FS Fats (also known as lipids) are a macronutrient. The main function of fats is as fuel for energy. Fats are a rich source of energy, providing 37 kilojoules per gram. This explains why foods high in fat but low in other valuable nutrients are referred to as energy-dense foods. Fats are an important part of a balanced diet, but some types of fats are better for health than others. Most people get enough fats in their diet. In fact, Australians are more likely to overconsume than underconsume this nutrient, particularly the type known as saturated fats. As all fats contribute 37 kilojoules per gram, if they are eaten in excess they contribute to weight gain and obesity and associated effects, such as increased risk of cardiovascular disease, diabetes mellitus (type 2) and colorectal cancer. Fats are classified according to their chemical make-up and are categorised into four broad types (see figure 5.6). Regardless of the type of fat, they all contribute the same number of kilojoules of energy per gram to the body. PR O O eLesson: Omega 3 Searchlight ID: eles-0221 E Unit 3 AOS 1 Concept 3 PA G See more Fat Topic 8 TE D All fats Polyunsaturated Saturated Trans fats Omega 3 O R R EC Monounsaturated U N C Omega 6 Unit 3 AOS 1 Do more Fat Topic 8 Concept 3 218 FIgURE 5.6 The different types of fat Monounsaturated fats Monounsaturated fats are considered one of the more healthy types of fat, though their energy contribution is still 37 kilojoules per gram. Monounsaturated fats can assist in the lowering of low density lipoproteins (LDL, the ‘bad’ cholesterol). (See page 47 in Chapter 2 for more information on cholesterol.) The exact mechanism of this process is not fully understood, but replacing saturated fats with monounsaturated fats decreases the level of LDL cholesterol, reducing the risk of atherosclerosis and cardiovascular disease. Monounsaturated fats have also been shown to decrease the impact of impaired glucose regulation and decrease the risk of type 2 diabetes when consumed in place of saturated fat. In moderation, UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 218 11 June 2015 7:57 PM therefore, monounsaturated fats can have positive health effects. Like any fat, however, too much will still contribute to weight gain, obesity and associated conditions. O PR O Monounsaturated fats are liquid at room temperature and begin to solidify when placed in the refrigerator. Foods rich in monounsaturated fats include: • olive oil • avocado • canola oil • nuts • peanut butter. FS Food sources of monounsaturated fat Polyunsaturated fats O R R EC TE D PA G E Polyunsaturated fats are also considered one of the more healthy types of fat, although they contribute the same kilojoule value as other types. The greatest gains are achieved when saturated and trans fats are replaced with monounsaturated and polyunsaturated fats. There are two main categories of polyunsaturated fats: omega 3 and omega 6. Both omega 3 and omega 6 fats act to lower LDL cholesterol in the blood stream and increase HDL cholesterol, therefore reducing the risk of heart disease. Polyunsaturated fats also have other functions: • Omega 3 polyunsaturated fats appear to promote the elasticity of blood vessels, which can reduce blood pressure and the risk of cardiovascular disease. • Omega 3 polyunsaturated fats also prevent blood clots in the arteries. Blood clots can block blood flow in blood vessels and are one of the causes of heart attack and stroke. • According to the American Heart Foundation (2009), omega 6 polyunsaturated fats decrease the impact of impaired glucose regulation and ultimately decrease the risk of developing type 2 diabetes. • Polyunsaturated fat reduce the impact of inflammation of blood vessels and can reduce the risk of cardiovascular disease as a result. These two types of fat need to be eaten in appropriate ratios to achieve their full benefit. Adults should be eating omega 3 and omega 6 fats in a ratio of about 1 : 4. Very few people are deficient in these types of fats, but most people tend to eat too much omega 6 fat. C Food sources of polyunsaturated fats U N Polyunsaturated fats are generally liquid at room temperature and when refrigerated. Food sources for omega 3 fats include: • fish (particularly oily fish such as mackerel, trout, sardines, tuna and salmon) • soy and canola oils, and canola-based margarine. Food sources for omega 6 fats include: • most nuts and seeds • corn, safflower and soy oils. Saturated fats When overconsumed, saturated fats are often associated with negative effects on health. Saturated fat has been shown to increase LDL cholesterol production in Figure 5.7 Oily fish such as mackerel are a good source of omega 3. Nutrition and the NHPAs • CHAPTER 5 219 c05NutritionAndTheNHPAs.indd 219 11 June 2015 7:57 PM 5.2 The nutrients and the NHPAs: Fats and water the liver and also contains substantial amounts of LDL cholesterol, which can contribute to atherosclerosis and cardiovascular disease. Diets high in saturated fat have been shown to increase the impact of impaired glucose regulation and the risk of type 2 diabetes. Although saturated fat can increase the risk of obesity, which is a risk factor for colorectal cancer, excessive saturated fat intake also appears to increase the risk of colorectal cancer directly (that is, even in people who are not obese). FS Food sources of saturated fat PA G Trans fats E PR O O Saturated fats are mostly found in foods of animal origin and are usually solid at room temperature. Examples include: • fatty cuts of meat. Saturated fat can be seen along the edges and through some meats. • full cream milk, cream and cheese • coconut milk and cream • most fried takeaway food • most commercially baked goods such as pastries and biscuits. Trans fats behave much like saturated fats in the body by raising LDL cholesterol levels. Trans fats also work to decrease levels of HDL cholesterol, thereby increasing the risk of cardiovascular disease. Trans fats can also interfere with the structure of cell membranes, which can affect the movement of nutrients and fluids in and out of the cells. If glucose is restricted from entering the cells, insulin levels increase in response to the higher blood glucose levels. This can contribute to insulin resistance and increases the risk of type 2 diabetes. TE D FIgURE 5.8 The visible fat on meat is largely saturated fat. Energy input Energy output O R R Lose weight = EC In order to lose weight, energy intake must be less than energy output: U N C If a person wants to gain weight, energy intake must be more than energy output: Gain weight = Energy output Energy input To maintain weight, energy input and energy output must be equal: Maintain weight = Energy input Energy output FIgURE 5.9 The effects of different energy inputs and outputs 220 Food sources of trans fats Although small amounts of trans fats are found naturally in certain foods, including beef, mutton and dairy products, most trans fats are created when liquid oil is converted into solid fat by a process called hydrogenation. For this reason, trans fats are generally found in processed foods, such as pies, pastries and cakes. Margarines and solid spreads made for cooking are sometimes high in trans fats and should make up only a small part of the diet. The nutrition information found on packaging of processed foods usually indicates how much trans fat the food contains. By consulting these labels, consumers can choose foods with little or no trans fats. The relationship between food and body weight In order to lose, gain or maintain body weight, the balance between energy intake (energy consumed) and energy output (energy expended) is important. UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 220 11 June 2015 7:57 PM Carbohydrates, protein and fat (energy intakes) that are not used for energy production can be stored as adipose tissue (fat), so someone who continually takes in more energy than they use risks becoming overweight and/or obese. Obesity is a risk factor for many other conditions, such as type 2 diabetes, colorectal cancer and cardiovascular disease, and can reduce an individual’s overall level of health. E O PR O Although it has no nutritional value, water is vital for human survival. Water makes up between 55 and 75 per cent of our body mass. Water is needed for many functions within the body. The amount of water required daily ranges from about 1.2 to 3 litres. As water contains no nutrients and therefore no energy, it can assist with weight management when consumed instead of other fluids. Regular consumption of water can reduce the risk of obesity and related conditions such as cardiovascular disease and diabetes. Water is also absorbed by fibre and therefore plays a role in digestive health and the prevention of colorectal cancer. FS Water PA G Sources of water Unit 3 AOS 1 Topic 8 See more Water Concept 4 R R EC TE D Most people’s daily intake of water does not come from drinking water at all. In fact, all food and drink contains water, and this is where most people get a majority of their supply Water in its purest form is the best source, as many other fluids contain additional kilojoules (as a result of added sugars and other additives) and no other valuable nutrients. Major sources of water include: • water in its pure form • other drinks that contain water, such as cordials, soft drinks, tea and coffee • fruits, including apples, watermelon, oranges, grapefruit and tomatoes • vegetables such as celery, broccoli, lettuce, carrots and cucumber. O TEST your knowledge U N C 1 (a) What are the main functions of fats in the body? (b) How much energy does one gram of fat provide? 2 (a) What are the four types of fat? (b) List four food sources for each type of fat. (c) Which two fats are considered the ‘bad’ fats? Why? 3 Outline the health benefits of polyunsaturated fat. 4 What are trans fats? APPLY your knowledge 5 Per gram, which nutrient contributes the most energy: carbohydrate, protein or fat? 6 Outline the similarities and differences between: (a) monounsaturated and polyunsaturated fats (b) saturated and trans fats. 7 Why would it be a good idea to replace most drinks with pure water? 8 Even though we should replace saturated and trans fats with monounsaturated and polyunsaturated fats, why is it important to not increase overall fat intake? 9 Explain how fats can address cardiovascular disease. 10 Identify and explain any relationships that exist between obesity, cardiovascular disease, diabetes mellitus, colorectal cancer, osteoporosis and: (a) monounsaturated fat (b) polyunsaturated fat (c) saturated fat (d) trans fat (e)water. Nutrition and the NHPAs • CHAPTER 5 221 c05NutritionAndTheNHPAs.indd 221 11 June 2015 7:57 PM 5.3 he nutrients and the NHPAs: Calcium, T phosphorus, sodium and vitamin D KEY CONCEPT Understanding the role that nutrients play in addressing health conditions identified within the NHPAs: calcium, phosphorus, sodium and vitamin D FS Calcium R O C U N Calcium phosphate Males Females Peak bone mass Menopause EC Bone mass TE D PA G E PR O O Calcium is the most abundant mineral in the body. Most of the calcium in our bodies (about 99 per cent) is stored in the bones, with the other 1 per cent in the blood, muscles and intracellular fluid. Perhaps the most important role of calcium is as a hardening or ossifying agent for hard tissue such as teeth, bones and cartilage. Calcium is capable of moving in and out of the bones and will move out of the bones if there are insufficient amounts available in the blood for other body functions. If an individual does not get enough calcium throughout their life, they are less likely to achieve their optimal peak bone mass. The more bone mass that is built up in the early years (particularly during youth), the greater the chance the person has of maintaining good bone health throughout life. If optimal peak bone mass is not achieved, the individual is at greater risk of developing the NHPA condition of osteoporosis and suffering from fractures later in life (see figure 5.10). Bone matrix Figure 5.11 The ossification process Gradual loss of bone mass in old age Puberty; bone size increases R The growth of hard tissue starts with the laying down of the bone matrix, which is like a framework for the bone structure. The bone matrix is largely made up of collagen, which consists of protein and vitamin C and provides ‘storage holes’ for calcium phosphate. Once the matrix is in place, crystals of calcium phosphate fill the holes, which makes the tissue strong and hard. This process is known as ossification. Ossification is much like dipping a sponge into a bucket of plaster. The once‑soft sponge maintains its shape but becomes very hard as the plaster dries. The matrix is like the sponge and the calcium phosphate is like the plaster. They are both needed for adequate bone formation. Once bones have stopped growing, ossification continues to replace old crystals with new ones. As people age, this process becomes less efficient and more crystals need replacing than the body can produce. This leads to weaker bones after the age of about thirty (see figure 5.11). 0 20 40 Age (years) 60 80 Figure 5.10 Bone mass over the life span for males and females Source: Medical Research Council, www.mrc-hnr.cam.ac.uk/research/bone-health/pbm.html. Food sources of calcium Good sources of calcium are dairy products such as milk, cheese and yoghurt. Other sources include: • sardines and salmon (with bones) • green leafy vegetables, such as broccoli and spinach • fortified soy milk • tofu made with calcium sulphate • fortified orange juice. Phosphorus Phosphorus has a number of roles in the body. Its main function is to work with calcium to harden or ossify bones and teeth. Calcium and phosphorus bind to 222 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 222 11 June 2015 7:57 PM form calcium phosphate, which is the ossifying agent for hard tissue. As a result, adequate intake of phosphorus is important to decrease the risk of developing osteoporosis. Australians tend to get sufficient phosphorus in their diet, but certain conditions, such as diabetes and alcoholism, can prevent it from being absorbed, leaving the individual with low levels of phosphate. This can cause loss of bone density, weakness and poor appetite. O PR O As phosphorus is an important part of all living things, it is found in most foods. Foods that are rich in protein are particularly rich in phosphorus and include: • dairy products such as milk, cheese and yoghurt • meat such as chicken and beef • eggs • fish • nuts • legumes. FS Food sources of phosphorus PA G E Sodium Figure 5.12 Calcium and phosphorus are required to maintain the health of bones. O R R EC TE D Sodium is an important mineral for human life. It plays a role in the regulation of fluids in the body, including water and blood. Fluid is drawn to sodium, so the amount of sodium in the blood influences the amount of fluid that stays in the cells. Through this mechanism, sodium regulates the balance between fluid in the cells (intracellular fluid) and the fluid outside the cells (extracellular fluid). Most Australians get more than enough sodium in their diet. According to the Better Health Channel, the average Australian consumes eight to nine times the amount of sodium they need for good health. High levels of sodium in the body can draw excess fluid out of the cells. This increases blood volume and contributes to hypertension. Other effects linked to excessive sodium intake include: • heart failure. Increased blood volume and hypertension force the heart to work harder. Heart failure can result if the heart cannot keep up with demand from the body • stroke and heart attack. Hypertension associated with excess sodium intake contributes to higher rates of stroke and heart attack • osteoporosis. Excess sodium causes calcium to be excreted in urine, which can lead to the demineralisation of bones and the NHPA condition osteoporosis. C Food sources of sodium U N Foods containing sodium include: • table salt • olives • fish • meat (especially pork) • cheese • many processed foods, such as tomato sauce, packet soups and sauces, canned vegetables, pizza, pies and ready meals. Vitamin D Figure 5.13 Excess sodium increases blood volume and contributes to hypertension. Vitamin D is required for the absorption of calcium and phosphorus from the intestine into the blood stream. Due to the essential role that calcium and phosphorus play in the formation of hard tissue such as bones and teeth, a lack of Nutrition and the NHPAs • CHAPTER 5 223 c05NutritionAndTheNHPAs.indd 223 11 June 2015 7:57 PM 5.3 The nutrients and the NHPAs: Calcium, phosphorus, sodium and vitamin D See more Calcium See more Phosphorous Topic 8 Concept 5 Food sources of vitamin D O Unit 3 AOS 1 FS vitamin D leads to weakened bones and teeth. Osteoporosis (weak, frail bones) is a common musculoskeletal conditions caused by a lack of vitamin D. Most Australians get their vitamin D requirement from exposure to ultraviolet (UV) rays (from sunlight). UV rays are converted to vitamin D in the skin. Vitamin D deficiency was not a major concern in the past, as most Australians were exposed to enough UV rays to synthesise adequate amounts of Vitamin D. However, as more and more people heed the sun safety message, the amount of exposure to UV rays has decreased, and vitamin D deficiency is becoming more common. This is particularly the case in elderly people, as they are more likely to spend extended periods indoors. PA G E PR O Vitamin D does not occur naturally in many foods. Fish (particularly tuna, salmon, mackerel, sardines and herring) is the best source of vitamin D. Small amounts can also be found in: • beef liver • cheese • egg yolks. Some brands of milk, breakfast cereals and orange juice are fortified with vitamin D, but it is important to check the packaging. TEST your knowledge APPLY your knowledge 5 Describe the symptoms that might be present for someone who was not getting enough: (a)calcium (b) vitamin D. 6 Why is a deficiency in calcium during the younger years not likely to affect health until later life? 7 Use the Calcium calculator links in the Resources section of your eBookPLUS to find the weblink and questions for this activity. 8 (a) Why do most Australians get enough vitamin D? (b) Which groups of people might be at risk of vitamin D deficiency? Explain why. 9 Explain how excessive sodium intake can contribute to: (a) cardiovascular disease (b)osteoporosis. U N C O R R EC TE D 1 (a)Using figure 5.11, describe the pattern of bone mass over the life span. (b) Which life span stages are the most important for building bone density? (c) Explain the role that calcium, phosphorus and vitamin D play in the prevention of osteoporosis. 2 (a) What is the bone matrix? (b) What is the bone matrix made from? (c) What is ossification? 3 Explain the possible impacts on health from consuming a diet high in sodium. 4 List three food sources for: (a)calcium (b)phosphorus (c)sodium (d) vitamin D. 224 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 224 11 June 2015 7:57 PM 5.4 The role of nutrients in addressing the NHPAs Risk nutrients Table 5.1 Risk nutrients Risk nutrients Saturated and trans fats R Cardiovascular health O PR O E Function Contains LDL cholesterol, which is a risk factor for atherosclerosis and therefore cardiovascular disease. Stimulates the liver to produce LDL cholesterol, which further increases atherosclerosis and cardiovascular disease. Can lead to weight gain, obesity and associated conditions, including cardiovascular disease. Sodium Can increase blood volume and contribute to hypertension as a result. Hypertension increases the risk of heart attack and stroke. O R Carbohydrates, protein and fats Carbohydrates, protein and fats Can lead to weight gain and obesity, increasing the risk of diabetes mellitus. Trans fats Can interfere with cell membranes and contribute to high blood glucose levels. This can contribute to impaired glucose regulation and diabetes mellitus. Saturated fat Can reduce the ability of the body to effectively use insulin, contributing to increased risk of impaired glucose regulation. Carbohydrates, protein and fats Can lead to weight gain and obesity, increasing the risk of colorectal cancer. Saturated fat Appears to increase the risk of colorectal cancer. Obesity Carbohydrates, protein and fats Can lead to weight gain and obesity if not used for energy. Osteoporosis Protein Excess protein intake can increase the loss of calcium from bones, which increases the risk of osteoporosis. Sodium Excess sodium causes calcium to be excreted in urine, which can decrease bone density and contribute to osteoporosis. Protein deficiency may reduce bone density and increase the risk of osteoporosis. U N C Diabetes mellitus Figure 5.14 Fruit and vegetables are packed with protective nutrients and have small amounts (if any) of the risk nutrients. EC Condition TE D Many nutrients can contribute to ill health if they are overconsumed. These nutrients and the related conditions are summarised in table 5.1. PA G As we have seen, there is a strong relationship between nutrients and conditions included in the NHPAs. Nutrients that tend to put people at risk of certain diseases are known as risk nutrients. Those that protect people from diet-related diseases are known as protective nutrients. This section summarises the risk and protective nutrients related to health conditions in several NHPAs, including cardiovascular health, diabetes mellitus, colorectal cancer, obesity and osteoporosis. FS KEY CONCEPT Understanding the role of nutrition in addressing conditions recognised in the NHPAs: cardiovascular disease, diabetes mellitus, colorectal cancer, obesity and osteoporosis, including the function and major food sources of protein, carbohydrates (including fibre), fats (mono, poly, saturated and trans), water, calcium, phosphorus, sodium and vitamin D. Colorectal cancer Nutrition and the NHPAs • CHAPTER 5 225 c05NutritionAndTheNHPAs.indd 225 11 June 2015 7:57 PM 5.4 The role of nutrients in addressing the NHPAs Protective nutrients Protective nutrients are those that play a role in promoting health. Individuals without a balanced food intake are at increased risk of being deficient in these nutrients. Some nutrients that play a protective role in some of the National Health Priority Areas are summarised in table 5.2. Table 5.2 Protective nutrients Obesity Increases feelings of fullness, which can reduce overeating, obesity and risk of cardiovascular disease. Reduces blood cholesterol levels, which reduces the rate of atherosclerosis and cardiovascular disease. Reduces LDL cholesterol, which reduces the rate of atherosclerosis and cardiovascular disease. Polyunsaturated fats Reduces LDL cholesterol, which reduces the risk of atherosclerosis and cardiovascular disease. Omega 3 increases elasticity of blood vessels and prevents blood clots, reducing the risk of heart attack and stroke. Increases HDL cholesterol, which decreases blood cholesterol levels. Water Contributes no kilojoules to energy intake, so can reduce the risk of obesity and associated conditions, including cardiovascular disease. Fibre Increases the feeling of fullness, which can reduce overeating, preventing obesity and reducing risk of diabetes mellitus. Reduces blood glucose levels, which can protect against obesity impaired glucose regulation and diabetes mellitus. Polyunsaturated fats May decrease the impact of impaired glucose regulation and reduce the risk of diabetes mellitus. Water Contributes no kilojoules to energy intake, reducing the risk of obesity and associated conditions, including diabetes mellitus. Fibre Fibre assists in moving digested food matter through the digestive tract and absorbs water, which adds bulk to faeces, making them easier to pass. The exact relationship between fibre and colorectal cancer is unknown but fibre appears to decrease the risk of colorectal cancer. Water Contributes no kilojoules to energy intake, so can reduce the risk of obesity and associated conditions, including colorectal cancer. Is absorbed by fibre and assists in flushing waste, which may decrease the risk of colorectal cancer. Fibre Provides a feeling of fullness without the kilojoules. This can reduce the amount of energy consumed from other foods, therefore preventing weight gain and obesity. Reduces energy intake by decreasing the absorption of glucose into the blood stream. This can mean glucose is not transformed into adipose (fat) tissue. E PR O Water Contributes no kilojoules to energy intake, so can reduce the risk of obesity and associated conditions, including cardiovascular disease. Calcium Acts as a hardening agent for the mineralisation of bones, which increases bone mass and reduces the risk of osteoporosis. R Osteoporosis O Monounsaturated fats PA G Colorectal cancer Fibre TE D Diabetes mellitus Function EC Cardiovascular health Protective nutrients FS Condition Works with calcium as a hardening agent for bones, which increases bone mass and reduces the risk of osteoporosis. Required for the absorption of calcium and phosphorus from the intestine into the blood stream, which increases bone density and decreases the risk of osteoporosis. U N C O Vitamin D R Phosphorus TEST your knowledge 1 What is meant by the terms ‘risk nutrients’ and ‘protective nutrients’? 2 Describe the role of nutrition in addressing the following NHPAs. (a) Cardiovascular health (b) Diabetes mellitus (c) Colorectal cancer (d)Obesity (e)Osteoporosis 3 What is the difference between saturated fat and poly-/monounsaturated fats with regard to their effect on cholesterol? 4 (a) What is cholesterol? (b) Why is too much LDL cholesterol a risk to the health of individuals? (c) Which NHPA are high cholesterol levels associated with? APPLY your knowledge 5 Provide two suggestions that could help someone reduce their levels of LDL (bad) cholesterol in their body. 6 Why is balance the key when it comes to risk and protective nutrients? Why wouldn’t you cut out risk nutrients altogether, or eat only protective nutrients? 226 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 226 11 June 2015 7:57 PM KEY SKILLS Nutrition and the NHPAs Topic 10 FS Concept 3 See more Colorectal Cancer See more Obesity Unit 3 AOS 1 Topic 10 See more Osteoporosis Concept 4 EC TE D PA G E PR O Many of the NHPAs, including cardiovascular health, diabetes mellitus, colorectal cancer (from the cancer control NHPA), obesity and osteoporosis (from the arthritis and musculoskeletal conditions NHPA) have nutrition as a significant risk factor. To be able to explain the links between nutrients and these conditions, a thorough understanding of the key nutrients examined in this chapter is essential, along with a sound knowledge of the function and food sources for each one. When studying the key nutrients, ensure you include the following: • the roles the nutrient plays in increasing or decreasing the risk of the condition. Some nutrients can be a risk and/or a protective factor for two different conditions. Ensure you know the range of roles that each nutrient plays. Do not restrict your knowledge to one or two NHPAs, as knowledge of all those listed above may be required • familiarity with a range of food sources. Be able to identify food sources of a particular nutrient from a range of food groups. You may be asked to list a nondairy source of calcium, for example. If a food source has the nutrient added artificially, state that it is a fortified food source (such as fortified breakfast cereal being a source of vitamin D). If an explanation of the role that nutrition plays as a protective factor against osteoporosis were required, the following could be included. People who consume enough nutrients for optimal bone health during years of rapid growth (such as youth) and throughout other life span stages are less likely to develop osteoporosis. Calcium and phosphorus❶ are essential for building peak bone mass.❷ Calcium and phosphorus join together to make calcium phosphate, the hardening material of bone.❸ In the right proportions, these nutrients can assist in reducing the risk of osteoporosis. Major food sources for calcium include milk, cheese, salmon (with bones) and fortified orange juice.❹ Major food sources for phosphorus include milk,❺ eggs, chicken and beef. Unit 3 AOS 1 O KEY SKILL Explain the role of nutrition in addressing specific conditions within the NHPAs, including the functions and major food sources of relevant nutrients. R PRACTISE the key skills O R 1Discuss the role that fats can play in addressing cardiovascular disease. 2Explain the possible health consequences for an individual who consumes excess sodium. 3Discuss the role that nutrition can play in addressing colorectal cancer. U N C Key skills exam practice (© VCAA 2006, from the written exam paper, 2006, Q.4b). Table 5.3 Disease burden attributable to overweight/obesity by condition, Victoria, 2001 Deaths DALYs % of total DALYs Type 2 diabetes Ischaemic heart disease Condition 1 190 1 255 23 479 113 579 3.6 2.1 Osteoarthritis Colorectal cancer Hypertension Ischaemic stroke Total burden 5 217 146 124 2 937 3 130 3 130 1 301 5 255 149 874 0.4 0.5 0.5 0.8 7.9 ❶ Simply listing the nutrients is a good start, but some further explanation is required; for example, ‘What role does each nutrient play in promoting health?’ ❷ Key terms are used. ❸ The specific role of each nutrient is explained. ❹ Major food sources are identified. Source: Adapted from Department of Human Services 2005, Victorian Burden of Disease Study, Mortality and Morbidity in 2001, Public Health Group, Rural and Regional Health and Aged Care Services Division, Victorian Government Department of Human Services, Melbourne, p. 87. ❺ Specific food items are used instead of food groups such as ‘dairy’. Nutrition and the NHPAs • CHAPTER 5 227 c05NutritionAndTheNHPAs.indd 227 11 June 2015 7:57 PM Key skills Nutrition and the NHPAs FS 4(i)Nutrition can be a risk factor for each of the conditions in table 5.3. Choose one of these conditions (except osteoarthritis) and show how a person’s food choices may be a risk for developing that condition. Condition chosen Nutrition as a risk factor for this condition U N C O R R EC TE D PA G E PR O O (ii)Nutrition can be a protective factor for each of the conditions in table 5.3. Choose one of these conditions (except osteoarthritis) and show how a person’s food choices may protect them against developing that condition. Condition chosen Nutrition as a risk factor for this condition 2 + 2 = 4 marks 228 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 228 11 June 2015 7:57 PM CHAPTER 5 review Chapter summary • Fibre is a type of carbohydrate that is essential for the health of the digestive system. It does not contribute any energy to the body because it passes through without being digested, reducing the risk of obesity. It can help reduce blood glucose and cholesterol levels and decreases the risk of cardiovascular disease and colorectal cancer. Chapter 5 definitions Searchlight ID: int-2918 PR O • The main function of protein is for the growth, repair and maintenance of body tissues. It can also be used as a source of energy when carbohydrate intake is low. Excess protein intake may contribute to weight gain and can decrease the amount of calcium in the bones. Protein deficiency may also reduce bone density and increase the risk of osteoporosis. Interactivities: Chapter 5 crossword Searchlight ID: int-2917 FS • The main function of carbohydrates is to provide the body with energy. They are the body’s preferred source of energy and contribute 17 kilojoules per gram. O • There are six categories of nutrients required for optimal health: carbohydrates, protein, fat, vitamins, minerals and water. E • The main function of fat is to provide a fuel for energy production. Each gram of fat produces 37 kilojoules of energy, making it a more concentrated source of energy than carbohydrates. PA G • Monounsaturated fats decrease LDL or ‘bad’ cholesterol and play a part in protecting people from cardiovascular disease. Chapter 5 concept cards HD34-031 to HD34-046 • Polyunsaturated fats increase HDL or ‘good’ cholesterol and decrease LDL cholesterol. Polyunsaturated fats also reduce blood clotting and inflammation and decrease the risk of cardiovascular disease as a result. TE D • Trans and saturated fats increase LDL cholesterol and therefore increase the risk of cardiovascular disease. Trans fats also interfere with cell membranes and can contribute to impaired glucose regulation. • Carbohydrates, protein and fat can all be stored as fat if not used for other functions. This can increase the risk of obesity and related conditions such as cardiovascular disease and type 2 diabetes. EC • If energy input is greater than energy output, weight gain results. R R • Water makes up a majority of body weight and is required for a range of functions, including for chemical reactions and as a key component of many cells, allowing them to function effectively. Water contains no kilojoules and may assist with weight management. • Calcium and phosphorus work together to harden bones and teeth. U N C O • Sodium assists in the regulation of fluid in the body and the functioning of the nervous system. Too much sodium can lead to high blood pressure or hypertension, and can also cause calcium to be excreted, therefore increasing the risk of osteoporosis. • Vitamin D assists in the absorption of calcium and phosphorus and is therefore important for bone health. Vitamin D is generated in the body when the skin is exposed to ultraviolet radiation. • Nutrients such as saturated fats, trans fats and sodium are collectively termed risk nutrients because if consumed in excess, they increase the risk of a range of health conditions. • Nutrients such as vitamin D, calcium and fibre are collectively termed protective nutrients because they decrease the risk of developing a range of health conditions. • Nutrients are important factors in increasing or decreasing the risk of health conditions within some NHPAs, including cardiovascular health, diabetes mellitus (particularly type 2 and gestational diabetes), colorectal cancer, obesity and osteoporosis. Nutrition and the NHPAs • CHAPTER 5 229 c05NutritionAndTheNHPAs.indd 229 11 June 2015 7:57 PM CHAPTER 5 review APPLY your knowledge 1 Copy and complete the following table for each nutrient covered in this chapter. 7 Are any nutrients both risk and protective nutrients? Explain. 8 ‘Australia is a land of overconsumption, and eating too much food causes all diet-related diseases in this country.’ Write a response to this statement using the knowledge you have gained in this chapter. 9 Draw up a table with two columns. Label one column ‘current foods’ and the other column ‘healthier options’. Write down everything you eat in a day and suggest substitutes that could improve your diet. Don’t forget to include drinks and snacks. 10 Use the Vegetarianism links in the Resources section of your eBookPLUS to find the weblink and questions for this activity. 11 Use the Fibre quiz links in the Resources section of your eBookPLUS to find the weblink and questions for this activity. O PR O U N C O R R EC TE D PA G 2 (a) Which nutrients are used as a fuel for energy? (b) What health concerns may arise if these nutrients are eaten in excess? 3 (a) What is the most abundant mineral in the body? (b) What is it used for? 4 Explain why a balanced diet is the best option for optimal health. 5 List three nutrients that contribute to cardiovascular disease. 6 Explain how vitamin D can affect the health of bones. E Possible Possible effects effects associated associated Food with with Nutrient Function sources deficiency excess FS TEST your knowledge 230 UNIT 3 • Australia’s health c05NutritionAndTheNHPAs.indd 230 11 June 2015 7:57 PM TE D EC R R O C U N E PA G PR O O FS