Food and Nutrition

1. NUTRITION
The study of food, its composition, the
amounts needed by the body and its
effects on the body
© PDST Home Economics

2. DEFINITIONS
 Food: any substance, solid or liquid, that contains
nutrients.
 Nutrients: substances that can be digested and used by
the body.
Elements: All nutrients are made up of elements. They are
simple substances that cannot be broken down into
anything simpler.
 Diet: the selection of food each person eats
 Balanced diet: contains all the nutrients in the correct
amount for the needs of the body.
 RDA: Recommended dietary allowance
 GDA: Guideline daily amount

3. Nutrients
There are 6 nutrients
 Proteins
 Fats / Lipids
 Carbohydrates
 Mineral elements
 Vitamins
 Water

4. Nutrients
 Macronutrients: needed in large amounts by the
body i.e. protein, fat and carbohydrate.
 Micronutrients: Needed in small amounts by the
body i.e. vitamins, minerals

5. Nutrients
 Composition: the elements that make up the
nutrients.
 Classification: dividing things into groups or
classes.
 Sources: foods that supply a large amount of a
nutrient.
 Functions: Uses of nutrients in the body

6. Protein - Composition
Made up of the elements:
 Carbon
 Hydrogen
 Oxygen
 Nitrogen
 Protein is the only nutrient with nitrogen which
is needed for growth
 The elements join to form Amino Acids
 The amino acids link together in long chains
called Proteins

7. Protein - Composition

8. Protein - Classification
There are 2 classes of protein
 1. HBV protein (High Biological Value)/ First
class protein / Animal protein.
 2. LBV protein (Low Biological Value ) / Second
class protein / Plant protein.
 Both classes of protein are needed in the diet

9. Protein - Sources
 Animal protein: meat, poultry, fish, eggs, cheese,
yoghurt, milk.
 Plant protein: Lentils, Beans, Peas, nuts, cereals
Plant protein foods contain:
 Less saturated fat
 More fibre
 Cheaper to produce

10. Protein - Sources

11. Protein - Functions
 The growth of all body cells
 For repair of worn or damaged cells
 To make hormones, enzymes and antibodies in
the body

12. Protein - functions

13. Protein – RDA and Energy value
 RDA for protein is 1g per day per Kg of body
weight.
 1 gram of protein can release 4 kilocalories or 17
kilojoules of energy

14. Test on Protein
1. Atoms of which elements make up protein?
2. What’s special about Nitrogen?
3. Name the small units that form proteins
4. Name the 2 classes of protein
5. List 5 food sources for each class
6. Give 2 functions for protein
7. What are the effects of protein deficiency
8. Are proteins micro or macro nutrients?
9. How much protein do we need per day?
10. What is the energy value of 1 gram of protein?

15. Lipids (fats & oils)- Composition
 Lipids are called fats when solid at room temperature
and oils when they are liquid at room temperature.
 Made of 3 elements:
 Carbon
 Hydrogen
 Oxygen
 The elements make units called glycerol and fatty acids
 Each glycerol joins to 3 fatty acids to form a lipid

16. Lipids - structure

17. Lipids - Classification
There are 2 classes of lipids
 1. Saturated lipids: animal fats, solid at room
temperature.
 2.Unsaturated lipids: plant and fish oils, liquid at
room temperature

18. Lipids - Sources
 1. Saturated fats are found in: butter, suet, lard,
meat, cheese, eggs, milk, yoghurt.
 2. Unsaturated fats are found in: fish, nuts,
seeds, cereals, soya beans, olives, avocado pears,
some margarines, cooking oils.

19. Saturated fat
sources

20. Unsaturated fat sources

21. Lipids - Function
 Releases heat and energy for the body
 Insulates the body
 Protects delicate organs e.g. kidneys
 Source of fat soluble vitamins A, D, E, K
 Delays hunger
 Adds flavour to foods

22. Functions of
fat

23. Overeating Lipids
 Overweight or obesity
 Saturated fats raise blood cholesterol. This
causes high blood pressure, strokes and heart
disease

24. Benefits of saturated lipids
 Help reduce cholesterol
 Omega 3 and omega 6 fatty acids reduce risk of
heart disease and improve brain function. They
are found in oily fish, seeds and nuts

25. Carbohydrates - Composition
 Made of 3 elements:
 Carbon
 Hydrogen
 Oxygen
 The elements form single sugar units e.g. glucose
 The sugar units link up to form other
carbohydrates

26. Carbohydrates-Classification
 There are 3 classes of carbohydrates
 Sugars
 Starches
 Cellulose (fibre, roughage)

27. Carbohydrates - Sources
 1. Sugars are found in: fruit, honey, table sugar,
cakes, biscuits, sweets, fizzy drinks, jam
 2. Starches are found in: bread, potato, pasta,
rice
 3. Cellulose is found in: Fruit, vegetables, whole-
cereals, seeds, nuts, beans, brown bread, brown
rice, high fibre breakfast cereals

28. Carbohydrate -
sources

29. Carbohydrate - functions
 To supply the body with energy
 Extra carbohydrate is changed to body fat and
stored
 Cellulose is needed to keep the digestive system
healthy and lower cholesterol

30. Cellulose
 Not digested, just passes through our digestive
system unchanged
 Helps to push food through the intestine and
prevent constipation, diverticulosis and cancer of
the colon
 We need to eat 30g of fibre a day to be healthy
most people only eat 15g

31. Sugar
 Sugar is a food we need to eat less of
 Too much sugar is causing obesity, tooth decay
and diabetes
 A lot of sugar is hidden in foods that don’t really
taste sweet especially convenience foods e.g.
spaghetti hoops, check label for ingredients

32. Reducing Sugar in your Diet.
 Replace sugary snacks with healthy fruit , nuts,
yoghurt etc.
 Drink water instead of fizzy drinks
 Sweeten breakfast cereals with fresh or dried
fruit e.g. raisins, banana
 Check sugar content on food labels and choose
low sugar foods

33. Vitamins – (micronutrients)
 Essential for good health
 Each vitamin has its own job to do in the body
 If a vitamin is missing from the diet a deficiency
disease can occur

34. Vitamins - Classification
 1. Fat –Soluble (dissolve in fat) Vitamins: A,D,E,K.
 2. Water – Soluble (dissolve in water) Vitamins:B, C
 If more of the fat soluble vitamins is eaten than the
body needs it is stored in the liver.
 If an overdose of these vitamins is eaten it causes
hypervitaminosis which is harmful to the body.
 Water soluble vitamins are not stored in the body, if too
much is eaten they are removed in the urine.
 It is therefore important to eat water soluble vitamins
every day

35. Fat soluble vitamins
Vitamin Sources Functions Deficiency
A
Carotene
(changed to vitamin A
in the body)
Oily fish, cod liver oils
liver/kidney
eggs, margarine
e.g. cabbage, spinach
Eyesight
Growth
Membranes/linings
of the body
Retarded growth
Night blindness
Unhealthy membranes /linings
D
Sunlight oily fish, cod liver oil, tinned salmon/sardines,
margarine, butter eggs,
Healthy bones and teeth
Rickets
Tooth decay
Osteoporosis

36. Water Soluble Vitamins
Vitamin Sources Function Deficiencies
B group
Folic acid
Meat, fish, eggs, cereals, flour, yeast, nuts,
pulses, Brown bread, supplements
Controls release of energy from food.
For a healthy nervous system
For growth of healthy foetus during pregnancy
Retarded growth
Tiredness
Beriberi
Pellagra
Neural tube diseases
C
Fruit, esp. blackcurrants, citrus fruit
e.g. oranges, strawberries. Veg. esp.
tomatoes, greens
Healthy skin & gum
Antioxidant
Fights infection
Strengthens blood vessels
Aids healing
Scurvy
Delayed healing

37. Test on Vitamins
1. Are vitamins micro or macro nutrients?
2. What are the two classes of vitamins and name the
vitamins in each class
3. List (a) 3 sources of vitamin A (b) 2 sources of carotene
4. What is the functions of vitamin D?
5. What happens if you are deficient in Vitamin B?
6. List 4 functions for vitamin C
7. What vitamin can be got from sunshine?
8. Which vitamin prevents scurvy?
9. What is hyper-vitaminosis?
10. Which vitamin works with calcium in the body?