Transcript Food and Nutrition

FOOD AND NUTRITION
Grade 8, Year 2011-2012
What is nutrition?
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Nutrition is the obtaining of food to provide energy
and substances needed for growth and repair.
Nutrients
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Nutrient is all useful substances needed by living
organisms.
There are 7 different nutrients needed for a
balanced diet for humans:
Carbohydrates, proteins, fats, vitamins, minerals,
fibre and water.
Carbohydrates
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Elements of carbohydrates: Carbon (C), Hydrogen
(H) and Oxygen (O).
Includes sugars and starches.
Sugars:
Monosaccharide: glucose, fructose, galactose
Disaccharides: Maltose, Sucrose, Lactose
Starches:
Polysaccharides: Starch, Glycogen and Cellulose
Where can we get carbohydrates?
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Starch: potatoes, bread, rice and other cereals.
Sugar :
Sucrose (table sugar) - drinks, jam
Glucose and fructose – fruits and vegetables
Proteins
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Elements of proteins: Carbon (C), Hydrogen (H),
Oxygen (O), Nitrogen (N) and sometimes Sulfur (S).
Protein molecules consist of long chains of amino
acids
Proteins provide the chemical substances needed to
build cells and tissues
Animal Protein: meat, fish, eggs, milk, cheese
Plant protein: wheat and maize
Fats/Lipids
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Elements of fats: Carbon (C), Hydrogen (H) and
Oxygen (O).
Fatty acids and glycerol will form fats.
Animal fats: meat, milk, cheese, butter and egg yolk
Plant fats: palm oil, sunflower seed oil
Fats are useful as long-term storage of energy, to
form part of the cell membrane, insulate body
temperature
Vitamins
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They are not broken down for energy
They are essential in small quantities for health
Vitamins are sometimes grouped into fat soluble
and water soluble
Name
Group
Source
Diseases and symptoms
caused by lack of vitamin
Vitamin A
Fat soluble
Liver, cheese, butter,
margarine, milk, eggs,
dark green and orange
vegetables and fruits
Reduced resistance to
disease, poor night vision
Vitamin C
Water soluble
Oranges, lemons,
tomatoes, grapefruits,
fresh green vegetables
Scurvy: Symptoms-Bleeding
gums, poor healing of
wounds
Vitamin D
Fat soluble
Butter, milk, cheese, egg
yolk, liver, fish liver oil
Calcium is not deposited
properly in the bones
Vitamin B1
Water soluble
Cereals, peas, and beans Beriberi
Vitamin K
Fat soluble
Green vegetables, also
made by colon bacteria
Defective blood clotting
Mineral Salts
Mineral Salts
Roles
Source
Iron
Part of haemoglobin molecule and takes
important part in carrying oxygen
liver, eggs, groundnuts,
bread, spinach
Calcium
• Deposited in the bones and the teeth
and makes them hard
• Present in blood plasma and plays an
essential part in normal blood clotting
Milk , cheese
Iodine
Needed in small quantities. It forms an
essential part of the molecule of thyroxine
(hormone produced by thyroid gland)
Sea fish, also present in
most vegetables
Phosphorus
Needed for calcium phosphate of bone
and also for DNA
Cheese, meat, fish
Water and Fiber (Roughage)
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Water acts as a solvent and as a transport medium
for digested food, salts, vitamins, and excretory
products (excess salt and urea).
Fiber can be found in plants. The cell wall of plants
consist of cellulose which is a carbohydrate that
can’t be digested in our body since we don’t have
enzyme that is responsible for that. Therefore,
cellulose will go directly to our large intestine and
will be digested by bacteria that live in it. Then, it
will also help the movement of waste through the
digestive tracts.
Questions
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List the components of a balanced diet for a human
Give one example of each of the following:
a simple sugar, a complex (double) sugar, a
complex carbohydrates.
Which elements are present in protein, but are not
found in carbohydrates and fats?
Name the small molecules that are joined together
to make protein molecules?