Food provides nutrients that the body needs for energy, growth, and maintenance. There are six major nutrients - carbohydrates, proteins, fats, vitamins, minerals, and water. Carbohydrates, fats and proteins provide energy, while vitamins and minerals aid chemical reactions and help regulate body functions. A balanced diet with varieties of foods containing these nutrients is necessary for health and well-being. Deficiencies in essential nutrients can lead to diseases, while excess calories can result in obesity.

1. LO2
What Humans Eat and Why?

2.  Food
◦ Is any substance, usually composed of
carbohydrates, fats, proteins and water,
that can be eaten or drunk by an animal or human for
nutrition
◦ Provides the energy and the materials needed to build
and maintain all body cells
 Nutrients
◦ Are the nourishing substances(chemicals) we, for the
most part, must obtain from food, that we need to live
and grow – to maintain a healthy body.

3.  Click on the picture to find out …

4.  Essential nutrients
 Are those nutrients
that a person must
obtain from food
because the body
cannot produce them
in large enough
quantities.
Rules for identifying an
essential nutrient:
 It must have a biological
function in the body.
 If it is removed from the
diet it has a negative
effect on one or more
biological functions.
 If it is replaced in the diet
it will restore the
biological functions for
which it is required.

5. Nutrients have several uses in the body:
 Provide energy.
 Provide materials for building,
maintaining and repairing body
tissues.
 Provide factors that regulate chemical
reactions in the body.

6. The body is made up of:
- 60% water.
- 23 to 31% fat for young women.
- 9 – 17% carbohydrates, proteins, minerals,
vitamins for young women.
Our diets provide these materials that
make up the body.
Carbohydrates
Proteins
Vitamins
Minerals
Fat
Water

7. Nutrients in the diet can be classified as:
 Energy yielding:
These include carbohydrates, fats and proteins.
They release energy when broken down by the body.
 Vitamins
 Minerals
 Water
Vitamins, Minerals and Water:
Do not provide energy for the body

8. The energy in food is
measured in calories or
kilocalories.
 A calorie is the amount
of heat needed to raise
1g water by 1o C
 In books or magazines
when the term calorie
is used it really means
kilocalorie (kcal)
“C” = 1 kilocalorie =
1,000 calories
https://phet.colorado.edu/en/simulation/eating-and-exercise

9. Carbohydrates- the mina source of energy in
the body
Carbohydrates include sugars and complex
carbohydrates.
The complex carbohydrates that we can
digest are called starches.
Carbohydrates are made up of the elements,
carbon, hydrogen and oxygen.

10.  CHO--- made of carbons, oxygen and hydrogen;
simple or complex based on the number of sugar
molecules present; 45-55% of total calories
 Functions:
◦ Major source of energy (glucose). 1 g of carbohydrate = 4
calorie
◦ Provides fibre
◦ Changed to protein- used to make tissues
◦ Excess is stored as fat, produce heat
 Sources: bread & cereal; pasta & rice; potato, lima
beans, corn; dried beans and peas; fruit,
vegetables & milk; sugar, syrup, jelly, jam, honey

11.  Are sugars.
 Occur naturally in
some foods such
as fruits and
vegetables.
 Also include
candy, jelly, soft
drinks, and
cookies.
 Supply energy.

12.  Are starches.
 Provide vitamins, minerals
and fiber as well as
carbohydrates.
 Include dry beans, starchy
vegetables like potatoes,
corn, and peas; rice, pasta,
oatmeal; bread and cereal.

13.  Plant materials that
are not digested
completely by the
body.
 Keeps the digestive
system healthy.
 Reduces the risk of
cancer and heart
disease.
 1 g of fibre = 1.5
calorie
Sources of Fiber:
Most Fruit and Vegetables
– both dry and fresh;
Whole wheat and bran;
Pulses – peas and beans

15. Lipids in our diet include fats and oils, and some
vitamins.
Lipids are also composed of carbon, hydrogen
and oxygen but they have fewer oxygen atoms
than carbohydrates.
Fats are lipids that are solid at room
temperature (20o C). – Example - butter
Oils are lipids that are liquid at room
temperature. – Example – olive oil
9 cal/g of energy

16.  We hear the term saturated fats and
unsaturated fats in the media.
 Saturated fats ( BAD) can raise blood
cholesterol (animal fat and butter are
saturated fats). These can clog up the
arteries.
 Many (but not all) oils are partly or mostly
unsaturated( GOOD) so are better for us.
Examples: Fish Oil (omega 3 and 6); olive oil.

17. Fats:
- Can be used for energy (9 cal per g of energy).
- They aid in absorption of fat-soluble Vitamins
(Vitamins A,D,E, K).
- Source of phospholipids (used to build cells).
- Insulate and protect body

18. Proteins are made up amino acids which
contain carbon, hydrogen, oxygen and also
nitrogen.
Amino acids are small molecules which are
joined together by bonds to make proteins.
The body contains 20 amino acids.

19. Main Function
Protein is needed for growth and repair. But it can also
be used for energy supply if there is no other source
(like carbohydrate and fats). 1 g of preotein generates 4
calories.
Beef burger
What other foods
provide protein?
Tuna

20. Proteins are:
- Used to build muscle and bone.
- Used as enzymes in chemical reactions.
- Used the body’s immune system which fights
disease.
- Are an important part of the blood.
- Provide a reserve energy source for the body.

21. The body makes some vitamins (Vit D and K) but
most vitamins come from food.
Kinds of vitamins:
◦ Vit A: prevents night blindness, skin diseases
◦ Vit D: increases Ca and P absorption
(helps in building and repairing bone).
◦ Vit E: increase Fe absorption
◦ Vit K: blood clotting

22. Vitamin A is needed for night vision.
What other
foods provide
Vitamin A?Carrot Eggs

23. Vitamin C is needed for the maintenance of
healthy skin.
What other foods
provide Vitamin C?
Orange Kiwi
Answer: all green
vegetables –
spinach, broccoli,
green cabbage etc

24. ◦ Group of Vitamin B
 B1(thiamine) - oxidize glucose
 B2 (riboflavin) - cell growth
 Niacin
 B5 - Pantothenic acid - mental
health
 B6 – red blood cells metabolism.
 B9 Folic acid - prevent anemia;
important for pregnant women to
avoid foetus abnormalities (spine
bifida)
 B12 - prevent anemia
 Biotin – nails and hair growth

26. - Vitamins act by helping chemical reactions to
occur or to happen faster.
- They do not provide energy for the body but
they help the body to release energy from
other nutrients.

27. Minerals are inorganic compounds which
means that they do not contain carbon.
 Macrominerals (minerals that are found in
amounts larger than 5 grams):
Ca, P, Mg, Na, K, Cl
 Trace minerals (minerals needed in daily
quantities of less than 100 mg)
Fe, Cu, Se, I, Mn, Mo, Zn, Cr, F

28. Iron is a mineral which is needed for healthy blood.
What other food
provides iron?
Roast beef Baked beans

29. Calcium is a mineral which is needed for the
growth and maintenance of strong bones and
teeth.
What other food
provides calcium?
Milk Cheese

30.  The human body is made up of about 63% water.
 Need 2.5 to 3 litres of water/day, but drink only
about 2.0 to 2.5 litres.
 Where do we get the rest??
The foods we eat contain water.
For example lettuce is 95% water.

31.  It acts as a solvent.
(dissolves materials)
 Transports food substances to
cells.
 Removes waste.
 Regulates temperature and
metabolic rate
(rate of chemical reactions in
body).

32. FOOD Pyramid: how much
and which foods to eat?

33. http://www.youtube.com/watch?v=IJnGFacO3Vs

34.  Suffering health consequences –
◦ Deficiency diseases
 Marasmus
 Scurvy
• Anemia
• Osteoporosis
• Rickets
◦ Afflictions of affluence
 Obesity

35.  Lack of protein
 Lack of food

36.  Deficiency of Vit C-needed for synthesis of
collagen
 Leads to the formation of
spots(thighs&legs) on the skin, spongy
gums, and bleeding from the mucous
membranes.
 Looks pale, feels depressed, and is
partially immobilized.
 In advanced scurvy there are open,
suppurating wounds and loss of teeth.

37.  Loss of bone
 fragile and brittle

38.  Iron deficiency anemia
 Fatigue
 decreased energy
 weakness
 shortness of breath
 lightheadedness
 palpitations (feeling of the heart racing or
beating irregularly)
 looking pale

39.  heart disease, congestive heart failure, and
stroke
 High blood cholesterol and triglycerides
(dislipidemia or high blood fats)
 High blood pressure (hypertension)
 High blood sugar (glucose) or diabetes
 BMI >30

40. One of the primary causes – Vitamin D
deficiency

41.  www.healthfinder.gov
 www.nutrition.gov
 webmd.com
 www.navigator.tufts.edu
 www.eatright.org
 What is a nutrient?
http://nutrition.about.com/od/nutrition101/a/nutrients.htm
 Good foods and Bad foods:
http://images.google.com/imgres?imgurl=http://tiki.oneworld.net/food
/food_title.jpg&imgrefurl=http://tiki.oneworld.net/food/food6.html&us
g=__FRxmehwQup5MCHnK3LstTrLjz-
4=&h=307&w=400&sz=17&hl=en&start=25&um=1&tbnid=-
C3T2td9e7CGOM:&tbnh=95&tbnw=124&prev=/images%3Fq%3Ddefine:F
oods%26ndsp%3D20%26hl%3Den%26rls%3Dcom.microsoft:*:IE-
SearchBox%26rlz%3D1I7ADBF_en%26sa%3DN%26start%3D20%26um%3D1
 http://www.mypyramid.gov/