A presentation about the diet we need to take, and healthy sources of it.

1. NUTRITION IN HUMANS
An interactive presentation by Fatima Salman

2.  All living organisms need to take in nutrients into their
bodies in order to be able to produce new cells, carry
out metabolic reactions and provide energy.
 Plants only need to take in inorganic substances, that
are carbon dioxide, water and mineral ions.
 From these inorganic substances, plants make organic
ones; that are carbohydrates, proteins and fats.
 Animals cannot make their own organic substances
from inorganic ones, so they have to take in
carbohydrates, proteins and fats.
 All of these nutrients have originally been made by
plants. We obtain these nutrients by eating plants, or
by eating animals that have eaten plants.

3. CARBOHYDRATES
The main function of carbohydrates is to provide us with
energy, as they are the body’s main source of fuel;
they are needed for respiration.
Carbohydrates are also needed to form supporting
structures, such as the cell walls in plants. They can
also be converted into other organic compounds, such
as amino acids and fats.

4. Carbohydrates
Sugars
Glucose
Sucrose
Lactose
Maltose
Polysaccharides
Starch
Glycogen
Cellulose

5. SOURCES OF CARBOHYDRATES
 Beans
 Fruits
 Milk
 Vegetables
 Legumes
 Nuts
 Yoghurt
 Wheat

6. FATS
The main function of fats is the same as carbohydrates:
to provide energy. They are often used as energy
stores, and are especially good at this because a gram
of fat contains twice the amount of energy as a gram
of carbohydrate.
Fats are also needed to build cells, because the cell
membrane of every cell is made of mostly fats. Stores
of fat beneath our skin are helpful for insulating our
bodies in cold weather.
Another function of fats is to reduce water loss from the
skin surface. Glands in our skin secrete an oily
substance, that forms a thin layer over our skin
surface, reducing the rate of evaporation of water.

7. However, an excessive consumption of fats in our diet
can be detrimental for our health. It can lead to being
overweight or obese, and may lead to illnesses such as
heart disease.
Therefore, it is usually better to have a moderate
amount of unsaturated fats in our diet.

8. SATURATED AND UNSATURATED FATS
Saturated
fats
Solid at room
temperature
Found mainly
in animal
based foods
Raise levels
of cholesterol
in your blood
Unsaturated
fats
Liquid at
room
temperature
Found in
plant foods
and fish
Good for your
body

9. SOURCES OF FATS
 Butter
 Cheese
 Fatty meat
 Olives
 Eggs
 Fatty fish
 Nuts

10. PROTEINS
Like carbohydrates and fats, protein can also be broken
down to release energy in respiration. However,
protein has many other functions in living organisms
as well.
Protein is needed for forming new cells, and is thus very
important for growth. All enzymes are proteins, which
are needed to catalyse metabolic reactions.
Some of our hormones are proteins as well, such as the
hormone insulin, which is secreted into our blood by
the pancreas to control our blood glucose level.

11. Haemoglobin is also a protein found inside red blood
cells. It transports oxygen from our lungs to all other
parts of our body.
Blood plasma contains proteins as well, called plasma
proteins. One of them is fibrinogen, which, if a blood
vessel is damaged, forms a blood clot across the
wound.

12. SOURCES OF PROTEIN
 Milk
 Meat
 Seeds
 Lentils
 Beans
 Eggs
 Seafood

13. VITAMINS
Vitamins are organic substance, however, unlike the
other three substances, they do not provide us with
energy, and we need only small quantities of vitamins
in our diet.
There are several different vitamins, and each one has a
particular function in our body. They usually help
metabolic reactions take place in our bodies.
If there is not a sufficient amount of any particular
vitamin in our diet, it can lead to illnesses called
deficiency diseases.

14. Vitamin C is needed to make collagen, an important
protein used to form skin, cartilage, tendons,
ligaments, and blood vessels. It is also needed for
healing wounds, and repairing bones and teeth.
A deficiency disease which results from a lack of Vitamin
C in the diet called scurvy. Symptoms of scurvy include
skin ulcers and swollen or badly damaged gums

15. Vitamin D is needed to absorb the calcium from our
food, as calcium is needed to build strong bones and
teeth.
A shortage of Vitamin D in our diet can lead to the
deficiency disease called ‘rickets’. Symptoms of rickets
include pain in the bones, bone fractures, and teeth
deformities.

16.  Fresh fruits
 Vegetables
 Citrus fruits (lemons,
limes and oranges)
 Dairy products
 Oily fish
 Egg yolks
 Sunlight
Sources of Vitamin C Sources of Vitamin D

17. MINERAL SALTS
Mineral salts are inorganic substances. Mineral salts are
needed in our diet for healthy growth and
maintenance.
An important mineral salt that we should take in our diet
is calcium. Calcium is needed for the formation of
bones and teeth, and other essential functions like
muscle contraction and blood clotting.
Another important mineral salt we need is iron. Iron is
needed for the formation of haemoglobin.
Haemoglobin is a protein found in red blood cells,
which transports oxygen around the body.

18.  Dairy products
 Fish bones
 Red meat
 Dates
 Figs
 Pomegranates
 Spinach
Sources of Calcium Sources of Iron

19. An insufficient amount of calcium in the diet can lead to
the deficiency disease ‘rickets’, in which the bones
become weak and brittle.
A lack of iron in the diet means that your body cannot
make enough healthy red blood cells. This can lead to
the deficiency disease called ‘anaemia’. Symtoms of
anaemia include feeling tired all the time, fatigue, and
weakness.

20. FIBRE
Fibre is not really a nutrient since we cannot digest it;
thus it doesn’t enter our bloodstream at all. However,
it is a very important component of a balanced diet
because it allows our digestive system to work
properly. It’s bulk makes the food keep moving
throughout the alimentary canal.
Taking a high fibre diet protects us from many diseases,
including cancer.

21. WATER
Water is an essential component of our diet. For
humans, it makes up nearly 70% of their body weight.
Water has many functions in the body. Substances are
dissolved in water in the cytoplasm of cells, allowing
them to react together. Blood plasma is mostly water;
it transports nutrients dissolved in it.
Water also helps us cool down in hot weather. Sweat is
mostly water, and as it evaporates from the skin, it
cools us down.
We obtain most of the water from the fluids we drink,
and some of it from fresh fruits and vegetables.

22. NOTES AND CREDITS
 All images have been taken from Google Images and I
take no credits for them.
 Textbook: O Level Biology, by Mary Jones; Oxford
 Textbook: Biology Matters; Marshall Cavendish
Education
 The internet