Unit 2: Food

and health

UNIT OBJECTIVES

• To learn about nutrients and diet

• To learn about food-related illnesses

• To study food preservation methods and product labelling

• To investigate how to prepare a balanced diet

1. Nutrients and diet

• 1.1. Differences between feeding and nutrition. Are they the same thing?

Eating or feeding

• It is a conscious, voluntary action and depends on different factors:

• Economic, climatic, religious, etc.

Nutrition

• It is an involuntary, unconscious process.

• Through nutrition, nutrients enter the cells to be absorbed and used in various metabolic processes.

• Systems involved in nutrition?

• Digestive, respiratory, circulatory and excretory system

Nutrients are substances that provides nourishment essential for the maintenance of life

and for growth: • Function of nutrients:

– Energetic: necessary energy to carry out vital functions. Example?

– Structural: to form our body tissues. Ex?– Regulating function: to control chemical

reactions in our organism: vitamin C

NUTRIENTS

• Energetic– Glucose: this nutrient travels in the blood to the cells

and it is used by the mitochondria to obtain energy for the cell

• Structural -Proteins: provide the structure for cells, tissues and organs,

replace damaged structures and enable growth and repair

• Regulating– Vitamin C (we cannot produce our own vitamines, we

must ingest them) (antioxidant, vision, synthesis of collagen for vessels, tendons, ligaments and bones..)

Classification of nutrients

• Water• Minerals: Structural and regulating functions

– i.e Phosforous: DNA, RNA, ATP, cellular membranes, bones.

• Carbohydrates: Energetic function– sugars and polysacharids

• Lipids: Energetic and structural function– oil..energy stored in our adipose cells. Migratory birds

use stored energy of triacylglycerols to fuel their flights

– Cell membranes

Classification of nutrients

• Proteins: many functions.e.g.– Haemoglobin: transports oxygen to cells– Enzymes, which catalyze chemical reactions:

amylase in our saliva, breaks up starch into sugar

– Collagen (connective tissue as cartilage)– Keratin: hair, nails…– Actin and tubuline make up the cytoskeleton

Classification of nutrients

• Vitamins: – vitamin A (retinol): vision (poor night vision)– Vitamin C (ascorbic acid): protects cells from

aging, production of fibres in the body (synthesis of collagen) (scurvy)

– Vitamin D (calciferol): D is needed for the absorption of calcium. (rickets)

Food Wheel

• Food is classified into six groups:– Group I: cereal and starches (carbohydrates)– Group II: oils and butter (lipids)– Group III: meat, egg, fish, nuts, legumes

(proteins)– Group IV: milk and derivates (proteins,

vitamins, minerals)– Group V: vegetables (vitamins and minerals)– Group VI: fruits (vitamins and minerals)

Activities you must answer in your notebook:

• Page 23: questions: 1, 2, 4 and 5

• Page 24: questions: 2 and 3

• Page 25:Work with the image:Questions 5, 6 and 8

• Page 27: questions 3, 4 and 6

• Page 28: questions 1, 2 and 3

• Page 30: questions 3 and 5

Page 26 The energy value of food:

• When nutrients from food enter the cell we

use them as fuel to produce energy through cellular respiration

Units of energy:

• The most common units are calories or kilocalories

• Joule or kilojoule is the unit of energy in the International System.

• 1 gram of carbohydrates has about 4 kcal

• 1 gram of lipids has 9 kcal

What is 1 kcal?

• The kilocalorie is approximately the amount of energy needed to raise the temperature of one kilogram of water by one degree Celsius. (symbol: kcal)

Why is cellular respiration important?

• Because nutrients are oxidized ( broken down) in the mitochondria and energy is produced from them.

• What by products does it produce?

Carbon dioxide and water

Daily energy needs

• Basal metabolic rate (BMR) is the rate of energy expenditure at rest or the number of calories you'd burn if you stayed motionless for a day.

• Energy expenditure varies by sex and age

• BMR is higher when a person is growing and lower when the person is older or has a low body mass

Page 28 A healthy, balanced diet:

• What makes for a healthy diet?

• How do you know if you are eating a balanced diet?

What makes for a healthy diet?

• Eat a variety of different foods

• Have 5 meals each day

• Eat fresh vegetables

• Avoid convenience foods

• Eat fibre-rich foods daily

What is a diet?

• Diet consists of all the food a person usually eats.

• Does the diet vary?

• Yes, it depends on each person´s physical activities, daily routines, soft diet are used if someone is suffering from a disease or after surgical operation ( food such as rice, chicken and fish is served, preferably boiled).

Page 28,Healthy, Balanced diet

• Diets should be balanced and contain nutrients in the right amounts to guarantee a healthy body.

• What are the recommendations for a healthy diet?

• Carbohydrates?..............55-60%

• Lipids?............................30%

• Proteins?........................15%

Page 28 Mediterranean Diet

• It is considered to be Balanced and healthy.

• It incorporates the traditional healthy eating habits found in southern Europe.

• It is based in the consumption

of olive oil, pulses, fish,

vegetables and fruit.

What are the health benefits from the Mediterranean diet?

• It prevents cardiovascular diseases and some cancers associated witth diet ( colon cancer) and it´s less likely to lead to obesity.

Page 30 FOOD PRESERVATION

• Food preservation is the process of treating and handling food to stop the loss of quality, edibility or nutritive value caused by microorganisms.

FOOD PRESERVATION METHODS

• Cold preservation methods: to prevent the growth of bacteria

» Perishable food lasts 5 days if kept 0º-4ºC in the fridge

» Perishable food lasts several months

if kept under -20ºC inside the freezer

Page 30 FOOD PRESERVATION METHODS

• Heat preservation methods– Applying high temperatures for a few

seconds. I.e. Pasteurisation (72ºC, cooling down quickly).

Pasteurization: It is a process that applies heat to destroy pathogens

• Sterilization: It requires temperatures higher than 100 ºC.

FOOD PRESERVATION METHODS

• Dehydration or drying:– Eliminating water using high temperatures

• Dehydrated foods Advantages of this method?

Advantages of dehydration

• Reduces volume and weight, so products are easier to manipulate, package and transport.

Activities from Page 30 3.- What is the main purpose of all food preservation processes?The main purpose of food preservation is to avoid the proliferation of microorganisms and to prevent the food from deterioration.

Why is this necessary?Because most food is perishable and it will be spoiled due to environmental and biological factors.

5.-Give 3 examples of foods preserved by each of the 4 processes described on page 30.

.- Examples of Foods that Are Commonly PasteurizedWhole Eggs Removed from Shells and Sold As a Liquid, Today, many foods, such as eggs, milk, juices, spices and ice are pasteurized.

.- Examples of foods preserved with sterilization: tuna tins.

.- Dehydration: Mushroom soup

.- Chemical preservation: Foods preserved by high sugar concentrations: jellies, syrups, juice concentrates; Vinergar preservers cucumbers as pickles.

FOOD ADDITIVES

• Substances added to food to improve its taste, preserve flavour, make it look more attractive and prevent it from spoiling.– Colourings: enhance natural colours to make

food look more attractive, or provide food with an attractive colour (colorants)

Questions: What does the following sentences refer to?

• The foods are subjected to temperatures of above 100ºC…..Sterilization

• The foods are subjected to temperatures between 0 and 4 ºC…Refrigeration

• The foods are subjected to temperatures below -18ºC….. Freezing

• The water is removed from foods….Dehydration.

Page 32. FOOD RELATED ILLNESSES

• FOOD POISONING: ingestion of food contaminated with microorganism or chemicals– Salmonellosis

Salmonella genus

FOOD RELATED ILLNESSES

• Food poisoning– Botulism

Clostridium botulinum

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium

FOOD RELATED ILLNESSES

• Salmonella– Eggs, meat, milk,

touching infected faeces

• Botulism– Home canned food

substances.

- Anaerobic bacteria that forms spores

Food allergies

• It refers to people who are sensitive to substances in food called allergens and react to them.

• E.g. Allergic to gluten ( protein in some cereals) suffer from celiac disease.

Page 32 Q 2.- Give examples of 3 microorganisms that can cause food poisoning.

Page 33 Q 9.-Make a table of food-related illnesses.

Causes Effects Food poisoning

Food allergies

Eating disorders

Micro organisms that can cause food poisoning

Name of bacterium Original source Risky foods Time to develop Symptoms

Bacillus cereus soilcooked rice and pasta; meat products; vegetables

1–5 hoursnausea, sickness and diarrhoea

Campylobacter jejuni raw meat and poultryundercooked meat and poultry; raw milk and cross-contaminated food

3–5 days of eating infected food

fever, severe pain and diarrhoea

Clostridium botulinum (very rare)

soilfaulty processed canned meat and vegetables; cured meat and raw fish

1–7 daysaffects vision, causes paralysis and can be fatal

Clostridium perfringens the environmentlarge joints of meat; reheated gravies

8-24 hours nausea, pain and diarrhoea

Escherichia coliE. coli O157:H7 is a very nasty strain it can be fatal

the gut of all humans and animals

contaminated water, milk, inadequately cooked meat, cross-contaminated foods

3-4 daysinflammation, sickness and diarrhoea

Listeria monocytogenes everywheresoft cheeses, paté, pre-packed salad; cook-chill products

variesfever, headache, septicaemia and meningitis

Salmonellagut of birds and mammals including humans - spread by faeces into water and food

poultry, eggs and raw egg products, vegetables

6-48 hoursdiarrhoea, sickness and headaches

Staphylococcus aureusthe skin and noses of animals and humans

cured meat; milk products; unrefrigerated, handled foods

2-6 hourssickness, pain and sometimes diarrhoea

Causes Effects or consequences Food poisoning Bacteria, viruses Symptoms:

Nausea Vomiting Diarrhoea Abdominal pain and

cramps Fever

Food allergies Your immune system in error identifies a

specific food or a substance in food as something harmful. Your immune system triggers cells to release antibodies to neutralize the food substance (the allergen). The next time you eat even the smallest amount of that food, antibodies sense it and signal your immune system to release a chemical called histamine, as well as other chemicals, into your bloodstream.

Allergic responses: dripping nose, itchy eyes, dry throat , rashes and hives, nausea, diarrhea, labored breathing, and even anaphylactic shock.

Eating disorders

Psychological and emotional health. Low self-esteem, perfectionism, impulsive behavior troubled relationships. Society. Success is often fuel this desire to be thin.

Abnormally slow heart rate and low blood pressure. Reduction of bone density which results in brittle bones. Muscle loss and weakness. Severe dehydration, which can result in kidney failure. Fainting, fatigue, and overall weakness. Dry hair and skin; hair loss is common.

Page 32. FOOD RELATED ILLNESSES

• Malnutrition: inadequate diet– Undernutrition (insufficient food): includes

rickets, anorexia and bulimia• RICKETS (raquitismo)

Lack of calcium and phosporus (vitamin D)Deformities of the bones

Activity round-up: Page 34

Questions 4: Define malnutrition, obesity, anorexia and bulimia.

Malnutrition is the condition that develops when the body does not get the right amount of the vitamins, minerals, and other nutrients it needs to maintain healthy tissues and organ function.

Obesity is an abnormal accumulation of body fat, usually 20% or more over an individual's ideal body weight. Obesity is associated with increased risk of other diseases such as diabetes and hypertension.

Anorexia is an eating disorder characterized by reduced appetite or total aversion to food. Anorexia is a serious psychological disorder. The person with anorexia try to lose weight by not eating. Therefore, they become extremely thin and weak. Anorexia can cause serious health problems and can lead to death.

Bulimia is an eating disorder characterized by episodes of excessive eating followed by inappropriate methods of weight control, such as self-induced vomiting , abuse of laxatives and diuretics.

Page 35. Interpret food labels.