Foods

Food is a solid or liquid that is taken through eating or drinking to provide necessary nutrients to the body.

Nutrition is the process by which living things take up food in order to grow and stay healthy

Functions of food

(i) To repair worn out tissue

(ii) Provide energy required to do work like talking and walking.

(iii) Protect the body against infections and diseases

(iv) To build the body.

Classification of foods and nutrients in food

They are classified according to the role they play when eaten

(a) Carbohydrates or energy giving food.

These provide energy when eaten.

Examples of foods that contain carbohydrates include, rice, maize, wheat, cassava tubers.

(b) Fats and oils

Fats are solids at room temperature while oils are liquids

Functions of fats and oils in the body

• Provide energy
• They are deposited beneath the skin to insulate the body against heat loss.
• They act as energy store
• The protect delicate organs against shock.

Sources of fats and oils

Animal fat

Sun flower

Sim sim

Ground nuts

Castor oil.

(c) Proteins are body building food

Functions of proteins

• Repair worm out tissues
• For growth

Sources of proteins

Animals: Fish, meat, chicken, pork

Plant sources: beans, peas, cashew nuts, soya bean

Deficiency of proteins causes kwashiorkor in children

Signs of and symptoms of kwashiorkor

Vitamins or protective food.

They are required in small amounts but protect the body against diseases. Lack of a particular vitamin in the diet may lead to deficient diseases

The table below shows types of vitamins, their sources, importance and name of deficient disease cause in their absence.

 

Vitamin	Source	Importance	Deficient disease
Vitamin A	Carrots, fruits, greens pumpkins	Good for skin and eyesight	Night blindness
Vitamin B	Cereals, liver, kidney and vegetables	Proper working of the brain,	Various diseases
Vitamin C	Fruits and vegetables	Healthy gum and skin	Scurvy
Vitamin D	Milk, sunlight	Strong bone and teeth formation	Rickets
Vitamin K	Vegetables	Clotting	Poor clotting

 

Mineral salts

Minerals are required in very small amounts but very important

The table below shows common mineral, their sources and uses

Mineral	Source	Importance	Deficient disease
iron	liver	Manufacture of red blood cells	anemia
Calcium	Meat, milk	Formation of bone
Phosphorus	Meat, eggs, beans	Formation of strong bones

 

Fibres/ roughages

They are thread-like  foods that prevent constipation or difficult in defecating.

Water

Role of water in in the diet include

• Soften food foe easy swallowing
• Prevents constipation
• Sweating cools the body
• Helps in digestion

Balanced diet

This is a diet consisting of the proper quantities and proportions of foods needed to maintain health or growth.

A balanced diet must have proteins, carbohydrates, mineral salts, water and vitamins in their right proportions

Examples of balanced diet include

• Breast milk
• Meat (proteins), posho (carbohydrates) and fruit juice (vitamins and water)
• Fish (proteins), millet (carbohydrates) and greens (vitamins)
• Beans (proteins), cassava (carbohydrates) and fruits-like apples (vitamins)

Deficiency diseases

They are diseases caused by lack of certain nutrients in the diet.

The table below shows the name of deficient disease, name of lacking nutrient, and common symptoms

Deficient disease	Lacking nutrient	Common symptoms
Marasmus or near starvation	Lacking enough food	–          Bones visible from skin –          Child is very weak –          Child cries a lot
Kwashiorkor	Proteins	–          Brown hair –          Swollen belly –          Loose skin –          Mouth sore
Anemia	Iron	–          Pale whitish skin –          One become weak and tire very fast
Rickets	Calcium	–          Bow legs in children
Goiter	Iodine	–          Swollen neck

Picture of deficient diseases

Food preservation

This is the treatment of food to enable long shelf life

Reasons for preserving food

(i) To prolong time in which it is useful

(ii) For storage

(iii) To avoid wastage

(iv) For easy transportation

Method of preservation include

Traditional methods

(a) Salting

This is often used to preserve fish and meat

Salt dehydrates and also kills germs

(b) Smoking

Smoking is used to preserve fish and meat

Smoke and heat kill germs. Heat dehydrates fish and meat

(c) Sun drying

Sun drying is used to preserve fish such as silver fish

It dehydrates.

Modern methods

(a) Freezing

Freezing is use to preserve meat, fish, chicken, fruits

Freezing paralyzes microorganism

(b) Canning

Foods like fruits, beans, meat and biscuits are preserved in metal cans.

(c) Pasteurization

Special groups

General all people must feed balanced diet for proper functioning of the body. However, balanced diet must be emphasized in the following groups of people

• Babies and children,
• Pregnant mothers,
• Elderly,
• The sick such as with HIV and
• Breast feeding mother

Food poisoning

This is the illness caused by eating contaminated food. This illness attacks the stomach but can spread to other parts of the body.

Causes of food poisoning

• food contaminated with poisons such as pesticides, detergents
• food contaminated with pathogens/disease causing organisms

Symptoms of food poisoning

• nausea and vomiting
• fever
• stomach pain
• dizziness
• headache
• death

How to prevent food from becoming poisonous

• proper storage of food
• eat fresh food
• do not eat expired food

For revision questions and answers download

Food and nutrition- upper primary

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Compiled by Dr. Bbosa Science + 256 778 633 682