Diet and Food Production

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

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.

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

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

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

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

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

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

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

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

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

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

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)

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

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).

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.

Atheroma

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

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

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

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

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

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

Atheromatous plaque

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

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

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.

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

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.

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.

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

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.

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

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

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

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

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

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

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

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

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

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

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)

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.

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

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

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

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

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

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

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.

Preventing spoilage Cooking Pasteurising Salting Pickling Freezing Irradiation

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