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 Nutrient Elements present Use in body
Good food sources
Carbohydrate
Carbon, hydrogen, oxygen
Source of energy
Rice, potato, bread
Fats and oils
Insulation
Butter, milk, cheese, egg yolk
Protein
Carbon, hydrogen, oxygen, nitrogen
Growth and tissue repair
Meat, fish, eggs, soya, milk

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)
Nutrient
Mass/g per day
Carbohydrates
250
Fats 80
Proteins 60
Minerals
9.2
Fibre 12
Vitamins
Traces
water
variable

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. Morbidly/severely obese (class 3)
Body Mass Index
BMI
Category
<18.5
Underweight
18.5 – 24.9
Acceptable
25 – 29.9
Overweight
30 – 34.9
Obese (class 1)
35 – 39.9
Obese (class 2)
>40
Morbidly/severely obese (class 3)

15. Prevalence of obesity Increasing in affluent countries In the UK
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 Cardiac arrest Angina
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.

32. 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.

33. 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

34. 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.

35. 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

36. 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

37. 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

38. 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

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

40. 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

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

42. 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

43. 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

44. 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

45. 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)

46. 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.

47. 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

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

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

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

51. Micro-organisms and Food Spoilage
Food spoilage begins as soon as an item is picked, slaughtered or manufactured.
Food poisoning is the presence of microbes or their toxins that cause illness or death

52. Micro-organisms and food spoilage
Visible growth (e.g. bread mould)
External digestion process
Clostridium botulinum produces botulin (toxin) - 1μg is enough to kill
Can cause infection e.g. Salmonella present in poultry
Aspergillus – produces carcinogenic toxins

53. Preventing food spoilage
In order to grow micro-organisms need:
Organic material
Water
Suitable temperature
Oxygen
Suitable pH
Food preservation removes one or several of these conditions.

54. Preventing spoilage Cooking Pasteurising Salting Pickling Freezing
Irradiation

55. Preventing contamination
To prevent further contamination
Canning
Vacuum wrapping
Plastic or paper packaging