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Diet and Food Production

Diet and Food Production

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Diet and Food Production

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  1. Diet and Food Production

  2. Learning Outcomes • Define the term balanced diet. • Explain how consumption of an unbalanced diet can lead to malnutrition, with reference to obesity.

  3. Starter Question • Nutrition come from the food we eat. • What advantages are gained from eating well? • E.g. better health • Stronger immune system • Ill less often • Learn more effectively • Make you stronger • Make you more productive.

  4. Next question • List the seven components of a balanced diet • Carbohydrates • Proteins • Fats • Vitamins • Minerals • Water • fibre

  5. The macronutrients

  6. Requirements of a balanced diet • Sufficient energy for our needs • Essential amino acids • Essential fatty acids • Micronutrients – vitamins and minerals • Water • fibre

  7. Guidelines (17 year old girl)

  8. Looking at the guidelines • Are these the same for everyone? • What factors will influence the energy requirements of different people?

  9. Energy intake • It is recommended that energy intake come from • 57% carbohydrates • 30% fats • 13% protein • In an active person the amounts of each of these will increase

  10. Malnutrition • Malnutrition is caused by eating an unbalanced diet • This could mean eating much more than is needed or much less

  11. Eating too little • A person who does not eat enough • Lacks energy • Shows signs of protein energy malnutrition • Can have deficiencies that impair health • Vitamin D – rickets • Vitamin C – scurvy

  12. Eating too much • Obesity is defined as when excessive fat deposition impairs health. • Body mass index > 30 • This is an indication that body weight is 20% or more above that recommended for your height. • BMI = mass in kg/(height in m)2

  13. Health risks associated with obesity • Cancer • Type 2 diabetes • Coronary heart disease (CHD)

  14. Body Mass Index

  15. Prevalence of obesity • Increasing in affluent countries • People eat more than they need • Take less exercise • In the UK • 25% men obese • 20% women obese

  16. Learning Outcomes • Discuss the possible links between diet and coronary heart disease (CHD). • Discuss the possible effects of a high blood cholesterol level on the heart and circulatory system, with reference to high density lipoproteins (HDL) and low density lipoproteins (LDL).

  17. Coronary Heart Disease • CHD is a degenerative condition • It involves the build-up of fatty tissue in the walls of the arteries that supply the heart muscle.

  18. Atheroma

  19. CHD • As a result of the build up • Arteries become narrow • Flow of blood decreases • Supply of nutrients and oxygen to heart muscle is restricted • The muscle does not release enough energy • The heart becomes weak

  20. CHD • Heart attack / myocardial infarction • A blood clot in the coronary artery cuts off the blood supply to an area of heart muscle. • Cardiac arrest • Severe heart attack / heart stops • Angina • Pain when exercising • Thrombosis • Development of a blood clot

  21. Lipoproteins • Lipoproteins • Made in the liver • Move cholesterol around the bloodstream • As cholesterol is water soluble, it is coated with phospholipids and proteins so that they can travel in blood plasma

  22. Structure of a lipoprotein • Phospholipids and protein coat • Centre • Cholesterol • Triglycerides • Other lipids

  23. Two types of lipoprotein • There are two types of lipoprotein • Low-density lipoprotein (LDL) • Transports cholesterol to the tissues • High-density lipoproteins (HDL) • Remove cholesterol from tissues and return it to the liver • HDLs have less lipid than LDL

  24. Cholesterol and CHD • If there is a tear in the endothelial lining of coronary arteries • LDLs enter the inner layer of the arteries • The cholesterol and fat that they carry are oxidised and build up • This forms an atheromatous plaque • This enlarges the wall, giving the arteries a rough lining

  25. Atheromatous plaque

  26. HDLs – “good” fat • Appear to protect against CHD by removing cholesterol from the tissues, including the tissues in the walls of blood vessels.

  27. It’s all about proportions • Health professionals are now less concerned about the quantity of cholesterol in the body • The focus is now on the proportions of HDLs and LDLs • The more HDLs - the less chance of heart disease

  28. Fats in diet • Diets rich in saturated fats tend to increase the cholesterol concentration of the blood due to a high LDL concentration • Polyunsaturated fats in foods, e.g. fish oils help protect against heart disease and lower the concentration of cholesterol in the blood.

  29. Diet and CHD • Antioxidants e.g. vitamin C and E • Protective and reduce the risk of developing CHD • Fresh fruit and vegetables are rich sources

  30. Question time!! • A study followed 639 people with a family history of CHD over a period of 14 years. Some has an LDL:HDL ratio of more that 8, while some had an LDL:HDL ratio of less than 8. The graph shows the probability of survival of a person in each of these groups over the 14 years of study.

  31. The questions • Explain why the survival probability is 100% at 0 years • Suggest why the graph is drawn so that it goes down in steps rather than in a smooth line. • Describe the conclusions that can be drawn from these data.

  32. The answers • This means that everyone was alive at the start of the study • Data collected once a year • Researchers did not know what happened in between • If one or more people died in a year the graph goes down by a step • Clear difference between results for people with high LDL:HDL ratio and the lower LDL:HDL ratio • The lower ratio had the greater probability of survival

  33. Learning Outcomes • Explain that humans depend on plants for food as they are the basis of all food chains. • Outline how selective breeding is used to produce crop plants with high yields, disease resistance and pest resistance. • Outline how selective breeding is used to produce domestic animals with high productivity.

  34. Food Chains • Food chains represent feeding relationships between living organisms • Plants are the basis of all food chains • Autotroph • Use an external energy source and simple inorganic molecules to make complex organic molecules • Photosynthesis

  35. Food Chains • All other organisms in the food chains are consumers • Heterotroph • Take in complex organic molecules as a source of energy • Your diet depends on plants

  36. Food Production • We can increase food production by making food chains more efficient • Plants • Improve growth rate of crops • Increase yield • Reduce losses due to pests and diseases • Animals • Increase rate of growth • Increase productivity • Increase resistance to disease

  37. Selective Breeding • Artificial selection is the intentional breeding of certain traits • Humans apply the selection pressure for the change in the population • Stages • Isolation • Artificial selection • inbreeding

  38. Selective Breeding in Plants • Examples • Tomatoes • Bred with improved disease resistance • Apples • Varieties with improved texture and flavour • Better quality • Nutritional value • flavour

  39. Selective breeding in Animals • Increase in the yield of meat, milk and eggs • Faster growing breeds • Farmed salmon • reduce time to market • Production of lean (low fat) meat • Egg laying chickens can lay up to 300 eggs per year

  40. Learning Outcome • Describe how the use of fertilisers and pesticides with plants and the use of antibiotics with animals can increase food production

  41. Fertilisers • Replace the minerals in the soil that are removed when crops are harvested. • Help to increase growth rate and the overall size of the crops

  42. Fertilisers • Artificial fertilisers contain • Nitrogen (ammonia or nitrate ions) • Make amino acids • Magnesium ions • Make chlorophyll • Potassium ions • Enzyme co-factors • For Guard cells to open stomata • Phosphate ions • Make DNA, RNA and coenzymes

  43. Pesticides • Pesticides are chemicals designed to kill pest species • Herbicide • Fungicide • Insecticide • Organic farmers use methods of crop rotation and biological control to control the number of pests

  44. Antibiotics • Antibiotics can be used to: • Reduce the spread of disease among intensively farmed animals • Add to animal feed to reduce the activity of gut bacteria (banned in EU)

  45. Learning Outcomes • Describe the advantages and disadvantages of using microorganisms to make food for human consumption. • Outline the methods that can be used to prevent food spoilage by microorganisms.

  46. Micro-organisms in food production • Micro-organisms are used in food technology, where they act as production agents • Turning ingredients into food • Modifying food ingredients

  47. Micro-organisms in food production • Bacteria • Cheese • Yoghurt • Fungi • Cheese • Single celled protein / mycoprotein • Yeast • Brewing • Winemaking • Bread making

  48. Advantages of using micro-organisms • Low fat foods – free from saturated fat and cholesterol • No ethical issues • Quick growth, high yields, fast production

  49. Disadvantages of using micro-organisms • Infection • Contamination of fermenters by competitors • Fungi, yeast and bacteria all use plant substrates • Purification • Palatability – taste and texture