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Think, pair and share a definition of nutrition. NUTRITION Definition of nutrition Nutrition is the science of food and its relation to health. It studies the nature of food, what happens to the food before we eat it, why we choose to eat certain foods and when happens to food in the body. Age, gender, size, activity level and state of health are all considered when calculating nutritional requirements. Nutrition is a vital factor in sustaining good health. Nutrients are substances that the body cannot make itself and are required for body processes including: Digestion and absorbing food Breathing Pumping blood around the body Filtering blood Growing and repairing body tissues Defending body against infection. Macronutrients are the nutrients that provide energy ie protein, carbohydrates and lipids. Micronutrients are the vitamins, minerals and trace elements needed to perform chemical reactions in the body. Copy and complete The problem for most Australians is not insufficient food, but deciding ___________________________________. It is essential to have some knowledge of food and nutrition because _____________________________________. Some foods relieve hunger _______________. Snack foods frequently __________________. Because the range of foods available is wide it can no longer be assumed _______________________________________. Affluent countries have many problems related to nutrition. For example, ________________________________________________. Obesity, heart disease, diabetes, alcoholism, gastrointestinal disease. People will choose the most nutritional foods. Some foods have little or no real nutritional value. But are not chosen for optimum health. Replace meals. Which foods are best. Copy and complete The problem for most Australians is not insufficient food, but deciding which foods are best. It is essential to have some knowledge of food and nutrition because Some foods have little or no real nutritional value. Some foods relieve hunger But are not chosen for optimum health. Snack foods frequently Replace meals. Because the range of foods available is wide it can no longer be assumed People will choose the most nutritional foods. Affluent countries have many problems related to nutrition. For example, Obesity, heart disease, diabetes, alcoholism, gastrointestinal disease. Nutrition The body consists of thousands of different substances, most of which can be made in the body from other substances. Some cannot be made – these are the nutrients and must be supplied by food. These are: Protein Carbohydrates Vitamins Minerals Lipids Water Fibre revision Quiz Game : Digestive System : Quiz on Nutrition, #1 Quiz Game : Digestive System : Quiz on Nutrition, #2 PROTEIN Every part of your body is made up from proteins. Proteins form different shapes for different cell structures eg muscles cells in long chins, flat sheets and networks in skin, hair and nails. Some proteins are messengers and workers in the body eg Antibodies are proteins that fight off infection, enzymes are proteins that help chemical reactions such as breaking down food, hormones are proteins that carry messages to increase or decrease body processes such as menstruation. New protein is needed for growth and repairs of old or damaged cells. Protein can be used as fuel if other energy such as carbohydrates and fats are unavailable. PROTEINS Proteins are made up of atoms of carbon (C), hydrogen (H), nitrogen (N) and sulphur (S). Proteins are made up of chains of carbon atoms joined in groups called amino acids. They are made up from an amino acid group (NH2) and a carboxyl group (COOH) and a radical which makes each amino acid different from each other. Amino acid structure Proteins Amino acids can form either 3D forms called globular proteins or long strands called fibrous proteins (either elastic or inelastic). Globluar proteins can be found in eggwhites, inelastic protein is meat gristle called elastin, and elastic proteins is the gluten in wheat. Amino Acids There are 22 amino acids, 8 are essential for adults and nine for children. Essential amino acids are not able to be made by the body and therefore must be supplied in the diet. Foods considered complete proteins contain all 8 essential amino acids. E.g. flesh from animals, animal products and soy protein. 8 Essential amino acids 1. 2. 3. 4. 5. 6. 7. 8. 9. Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine Histidine (infancy only) Amino Acids Limiting amino acid refers to the amino acid in shortest supply in the incomplete protein food. E.g. lysine is the limiting protein in rice and wheat. People with high protein needs such as the aged, children and pregnant women cannot store enough essential amino acids and it is important that they eat complementary proteins at each meal. Protein provides 17 kilojoules per gram Complementary proteins Combining 2 different plant sources that have different limiting proteins. E.g. bread with peanut butter, rice and lentils. Vegetarians must ensure that in a whole day intake that they consume complementary proteins. CARBOHYDRATES carbohydrates provide 16 kilojoules per gram Carbohydrates are the only source of energy used by the brain and red blood cells. The term refers to a range of sugars and starches found in many foods. They are classified into 3 groups – monosaccharides ( ‘one sugar’), disaccharides (‘2 sugars’) and polysaccharides (‘many sugars’). Glucose Carbohydrates 3 monosaccharides make up all the carbohydrates in our food – Glucose, fructose and galactose. disaccharides (are combination of 2 monosaccharides), examples; Sucrose consists of a glucose and fructose molecule eg.g common sugar Lactose consists of a glucose and galactose molecule e.g. milk sugar Maltose consists of 2 glucose molecules e.g. malt sugar. Polysaccharides Polysaccharides Polysaccharides, examples ; starch, glycogen, cellulose and pectin. Starch is a glucose polysaccharide found in plants. Glycogen is a glucose polysaccharide made in the body and stores glucose in liver and muscles. Pectin is found in the cells fruits and vegetables esp pith, seeds and peel. Essential in jam making to form a gel. Cellulose also called dietary fibre is part of cell plant walls. It cannot be broken down e.g. bran, oats. List which simple and complex carbohydrates you have eaten in the past 24 hours. (remember it includes sugars and starches) Lipids Lipids and fat cells in your body (adipose tissue) are an important source of energy and help to retain body heat. YouTube - The Human Body - Resources of Energy 5 other important functions of lipids. Provide padding to protect organs To carry fat soluble vitamins A, D, K and E. Provide essential fatty acids for nerve and brain function. Keep skin and hair soft and smooth. Lipids for part of the cell structure. Part of the messenger system forming part of hormones and prostaglandins (hormone like substances involved in muscle contraction and the immune system). Lipids Lipids are a group of substances that include fats, oils, fatty acids, phospholipids, sterols, glycolipids and waxes. Commonly lipids are made up of tryglicerides. These are made up from a glycerol molecule and 3 fatty acids chains. essential fatty acids are needed by the body and are liolic acid, linolenic and arachidonic acid. These are omega-3 and omega6 fatty acids found in oily fish and seafood, nuts and seeds and green vegetables. 1g lipid =37kJ energy Glycerol Lipids Our body needs cholesterol. It makes bile acids which help breakdown fats and absorb from food, makes some hormones. Our body makes it in the liver and is also obtained from animal fats. the 2 main lipid sources in our diet are Animal sources and plant sources. Plant sources are the healthiest because they contain no cholesterol and mostly unsaturated fats. These can lower heart disease and obesity. These food types are also a high source of vitamins and minerals. Vitamins Vitamins are substances that the body is unable to make itself. They can either be water soluble (B group and C), or fat soluble (A,D,K and E). They perform specific metabolic functions eg are necessary for the release of energy from proteins, fats and carbohydrates, and are enzymes that act as catalysts in chemical reactions. Water soluble vitamins cannot be stored by the body and must be consumed regularly. Fat soluble vitamins are stored in the body and can become toxic if intake is too high. Water soluble Vitamins Fat soluble Vitamins Vitamin function Vitamin D is in charge of your bones and control the rate of calcium and phosphate turnover. Vitamin E acts as an antioxidant capturing free radicals and reducing the impact of oxidative damage in cells. Vitamin C is involved in the formation of collagen which helps maintain the strength of cell walls and tissues e.g. skin. Folate (B9) is essential for the production and maintenance of body cells. Thiamin (B1)is essential in the process of releasing energy from carbs and lipids. Vitamin revision Quiz Game : Digestive System : Quiz on Vitamins, #1 Minerals Some minerals are needed in large amounts (calcium, iron, potassium, sodium, phosphorus, magnesium and sulphur), and some only as trace elements (small amounts) including iodine, copper, cobalt, manganese, molybdenum, chromium, selenium, nickel, vanadium and tin. Minerals Zinc is found in many enzymes and acts as a cofactor for other enzymes e.g. essential for obtaining energy from macronutrients, making new growth proteins. Zinc deficiency can cause retardation hair and skin problems and loss of taste. Zinc is found in oysters, liver, whole grains and nuts. Mineral sources Minerals and vitamin deficiency Rickets from Vitamin D deficiency Minerals revision Quiz Game : Digestive System : Quiz on Dietary Minerals Fibre It is possible to get fibre from supplements e.g. Metamucil, but it is preferable to gain the additional nutrients from food. There are 3 main types of fibre – soluble fibre, insoluble and resistant starch. These are classified by their role in the body. Soluble fibre (such as pectin and gums) is mainly found in plant cells. It dissolves in water and becomes a gel. Soluble fibre slows down the stomach-emptying and makes you feel fuller longer. Good sources include fruits, vegetables, oat bran, barley, dried beans, lentils, peas, soymilk and products. Fibre Insoluble fibre (such as cellulose, hemicelluloses and lignin) are parts of the cell walls of plants. Insoluble fibre can absorb water which adds bulk and helps the food pass through the digestive system. This helps prevent constipation. Good sources include wheat , corn and rice brans, skins of fruit and vegetables, nuts, seeds, dried beans and wholegrain foods. Resistant starch is found in plant foods that are not absorbed the small intestine. Good sources are firm bananas, chickpeas, unprocessed cereals and grains, potato and lentils. You must drink plenty of water with a high fibre diet to prevent dehydration. A varied diet for adults should include at least 5 serves of wholegrain cereals, 4 serves of vegetables and 3 serves of fruit. This would supply about 30g for dietary fibre. Interrelationships between nutrients Many nutrients require a combination to increase their efficiency e.g. folate and vitamin B12, sodium and potassium work together to maintain fluid balance in cells, balance pH levels in body, allows muscles to contract and relax. Iron has a positive relationship with vitamin C and a negative relationship with calcium, fibre and zinc. Calcium has a positive relationship with phosphorus, vitamin D and lactose. It has a negative relationship with fibre. Water Half body weight is water and without it we would die in 48 hours. Water enables transport of water soluble vitamins (B and C group), nutrients to pass through gut wall and into the blood system, maintains sodium/potassium balance. Acts as shock absorber in joints and lubricant e.g. saliva Helps control body temperature via perspiration Removes waste via kidneys as urine. Digestion Quiz Game : Digestive System : Interesting Facts about Digestive System Digestion of Food Digestion and absorption DIGESTION is the mechanical and chemical breakdown of food to its smaller nutritional components. ABSORPTION is the movement of these components from the gut into the blood and lymphatic systems. These systems deliver the nutrients to the cells or use in metabolic processes. Metabolism 2 main types of metabolism are catabolism and anabolism. Catabolism is when nutrients are broken down to their components, usually for energy of to make other substances. Anabolism occurs when new molecules are produced from substances released by catabolism e.g. new tissue built when recovering form injury. Organs of digestion Label the Diagram Game : Digestive System #1 Mechanical and chemical breakdown of food occurs in the mouth. Chewing (mastication) food mixes with saliva (mix of mucin and amylase ) triggers digestion of starch. Polysaccharides become disaccharides. Oesophagus joins the mouth and stomach. Food moves via peristalsis movement. No food is broken down here. Organs of digestion Stomach muscles grind food and mix with gastric juices (hydrochloric acid and ensymes) to produce chyme. This is released slowly into the small intestine. Gastric juices breakdown proteins into smaller polypeptide chains (peptones). Small intestine is in 3 parts – duodenum, jejunum and ileum. Peptones enter the duodenum and are broken down to amino acids by protein splitting enzymes. Digestion Pancreas produces pancreatic amylase which reduces remaining starches into maltose in the duodenum. Chyme enter the jejunum and comes in contact with enzyme invertase and become monosaccharaides ready for absorption. Pancreas also produces lipases to breakdown triglycerides into monoglycerides. Bile is made in the liver and stored and released from the gall bladder. Bile acts as a detergent to emulsify fats into smaller droplets so the lipases can act. Glycerol and fatty acids are absorbed through the ileum wall. Digestion The small intestine is covered in villi which absorb glucose, amino acids, water soluble vitamins and minerals into the bloodstream. Blood then transports these to the liver which coordinates use, storage or transport. Triglycerides and fat soluble vitamins first travel to the lymph system as chyle. This is released into the blood via the thoracic duct and then into the bloodstream for use as energy. Digestion Any unabsorbed water and fibre enter the large intestine to be excreted. The colon absorbs remaining water. Beneficial bacteria attack the fibre and other undigested components which produces a small amount of energy and some B group and Vitamin K. Remaining products, dead intestinal cells and bacteria are passed our as faeces.
