Food: any substance, solid or liquid, that contains
Nutrients: substances that can be digested and used by
Elements: All nutrients are made up of elements. They are
simple substances that cannot be broken down into
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
There are 6 nutrients
Fats / Lipids
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
Composition: the elements that make up the
Classification: dividing things into groups or
Sources: foods that supply a large amount of a
Functions: Uses of nutrients in the body
Protein - Composition
Made up of the elements:
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
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
Protein - Sources
Animal protein: meat, poultry, fish, eggs, cheese,
Plant protein: Lentils, Beans, Peas, nuts, cereals
Plant protein foods contain:
Less saturated fat
Cheaper to produce
Protein – RDA and Energy value
RDA for protein is 1g per day per Kg of body
1 gram of protein can release 4 kilocalories or 17
kilojoules of energy
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?
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:
The elements make units called glycerol and fatty acids
Each glycerol joins to 3 fatty acids to form a lipid
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
Adds flavour to foods
Carbohydrate - functions
To supply the body with energy
Extra carbohydrate is changed to body fat and
Cellulose is needed to keep the digestive system
healthy and lower cholesterol
Not digested, just passes through our digestive
Helps to push food through the intestine and
prevent constipation, diverticulosis and cancer of
We need to eat 30g of fibre a day to be healthy
most people only eat 15g
Sugar is a food we need to eat less of
Too much sugar is causing obesity, tooth decay
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
Reducing Sugar in your Diet.
Replace sugary snacks with healthy fruit , nuts,
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
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
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
Fat soluble vitamins
Vitamin Sources Functions Deficiency
(changed to vitamin A
in the body)
Oily fish, cod liver oils
e.g. cabbage, spinach
of the body
Unhealthy membranes /linings
Sunlight oily fish, cod liver oil, tinned salmon/sardines,
margarine, butter eggs,
Healthy bones and teeth
Water Soluble Vitamins
Vitamin Sources Function Deficiencies
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
Neural tube diseases
Fruit, esp. blackcurrants, citrus fruit
e.g. oranges, strawberries. Veg. esp.
Healthy skin & gum
Strengthens blood vessels
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?