6th Class Science Components of Food Components of Food

Components of Food

Category : 6th Class

Learning Objectives

1. There are 6 nutrients in our food; carbohydrates, fats, proteins, vitamins, minerals and water.

2. Deficiency of nutrients leads to deficiency diseases.

3. Fiber or roughage is also necessary for our digestive system.

4. A balanced diet is necessary to remain healthy.


We take food every day, it is the basic necessity of life. Food provides usenergy to work, to grow and protects us from diseases. Proper food keeps us ingood health.

The kind of food that we eat, depending on our liking and availability rawfood materials form our food habits. Some people eat wheat based mealswhereas some prefer rice based meals. Some take non-vegetarian food whileothers are vegetarians. However, in spite of the great diversity in the foodhabits of the people, we either consume food that are plant based or come fromanimals sources.



  1. Energy giving food: These food items provide energy to our body to dowork. g. sugar, cereals, jiggery, oil fats, starchy vegetables (potato, sweet potato) etc.
  2. Body building food: These food items are growth promoting. g. milk, pulses, meat, egg, fish etc.
  3. Protective food: Food items that protect our body against diseases fallunder this category. E.g. vitamins and minerals present in milk, greenleafy vegetables and fruits.



The main components of foods are carbohydrates, protein, fats, vitamins andminerals. These are called nutrients.


Carbohydrates are also called energy giving food. It is the main sources of energy It is made up of carbon, hydrogen, and oxygen. There are three types of carbohydrates.

(a) Sugars: It is a simple carbohydrate having sweet taste. Sources of sugarare glucose, Sugarcane, milk and fruits; such as banana, apple, grapes, etc.



(b) Starch: It is a complex carbohydrate. It is a tasteless, colour less, white power. Sources of starch are : wheat, maize, potato and rice.

(c)  Cellulose: It is present in plant cell wall. It is a complex carbohydrate.

Humans cannot digest cellulose.

Children, players and people who do manual work require more carbohydrates.



Protein helps in body growth and repairs the tissues so it is also called bodybuilding food. We get protein from milk, eggs, meat, fish and all kinds ofpulse.

Protein molecule is made of a large number of smaller molecules called aminoacid. The daily requirement of protein for adults is 1 gram per kilogram of thebody weight. When the body is building new tissue, more proteins are required, so growing children and pregnant lady need more protein.


Fats are made up of carbon, hydrogen and oxygen. Butter, ghee, milk, egg-yolk, nuts and cooking oils are the major sources of fat in our food.

An adult needs about 35 g fat every day. Our body stores the excess energy inthe form of fat. This stored fat is used by the body for producing energy as and when required so fat is considered as energy bank in our body. Fats are essential for the absorption of vitamins A, D, E and K in the body. Fat in our body alsoprevents heat loss from the body surface.



Vitamins are complex organic compounds which are essential for the growth and maintenance of our body. It does not provide energy. Our body requiresvitamins A, C, D, E, K and B-complex. Our body can make only two vitamins, Vitamins D and K so other vitamins must be present in our food. The B complex vitamin is a mixture of several water-soluble vitamins. The important vitamins of this group are the vitamin \[{{B}_{1}},{{B}_{2}},{{B}_{3}},{{B}_{4}},{{B}_{6}},{{B}_{9}}\]and \[{{B}_{12}}.\]

Minerals: Minerals are required by our body in very small quantities. Like vitamins, minerals help in keeping our body healthy. Iron, Iodine, calcium, phosphorus, sodium and potassium are common minerals. The sources of these. Minerals are plants and animals.

Milk, meat, fish, eggs, vegetables, fruits and pulses are some sources of a minerals.                            

Water: Water forms about 70% of our body weight. It is an important constituent of all body cells. Water is required for all the biological processes in our body although, water doesn't have any nutritive value, and it is very important component for the working of body.

Roughage: It is the fiber content which we obtain from our food. Roughagehelps in

  • Retaining water needed in body.
  • Adds bulk to our food.
  • Helps proper working of our digestive system

Sources of roughage are salad, fruits and vegetables.


Do You Know

At the time when vitamins were discovered, their chemical compositions were unknown. Hence they were represented by the letters of English alphabet.



Healthy Eating Habits: A balanced diet and regular exercise are veryimportant to students. A balanced diet refers to the selection of foods with appropriate portion to provide adequate nutrients and energy for the growth ofbody tissues, strengthening the immune system and keeping healthy bodyweight. Apart from taking sufficient fluid every day, eat according to the "Food Pyramid" to stay healthy.

In fact, the traditional Chinese diet where rice, vermicelli and noodles arestaple food, with lots of vegetables and moderate amount of meat, minimal preserved and processed food, coupled with healthy cooking methods usinglittle oil, is a perfectly balanced diet.



Do You Know

While playing or working in the hot sun, if a person loses too much water his body may get severely dehydrated. As a result blood becomes thick. This causes severe pain and cramps in the muscles.


The Importance of Balanced Diet

  1. A balanced diet provides energy and nutrients necessary for growth and helps maintain a healthy body weight.
  2. Nutrition replenishment is necessary to cope with the increased demandof energy for heavy home work and physical activities.
  3. A balanced diet can help prevent obesity, wasting, gastrointestinal diseases and anemia, as well as reduce chances of developing chronic diseases such as heart disease, high blood pressure, diabetes and cancer.


The types, functions and characteristics of food



Functions and characteristics

Grains and Cereals (e.g. Rice, vermicelli, noodles, bread, biscuits, cereals, corn flakes, whole- grain products)

Rich in starch, plant protein and moderate amounts of vitamin B and minerals. Main source of energy. Choose whole-grain food with high fiber content as it increases satiety and can prevent constipation.

Vegetables (e.g. Green leafy vegetable, squash, mushrooms, eggplant)

Rich in carotene, vitamin A and C and various minerals, able to strengthen the immune system and promote metabolism Rich in fiber, which increases satiety, helps lower body cholesterol and prevents constipation.

Fruits (e.g. Grapes, orange, apple, pear)

Dark green leafy vegetables (Chinese flowering cabbage, Chinese white cabbage, kale and broccoli etc) compared with other vegetables are rich in calcium, which can strengthen teeth and maintain healthy bones.

Meat and Beans (e.g. Beef, pork, lamb, poultry, fish, seafood, egg, beans, tofu)

Meat, seafood and eggs are rich in animal protein, minerals (e.g. iron, zinc) and vitamin B cony lex. Beans and bean products are rich in plant protein and minerals (e.g. calcium, iron, phosphorus) Protein is the basic element of cells and helps promote growth and repair cells.

Milk and milk products (e.g. low fat or skimmed milk/milk powder)

Choose lean meat, remove the skin and fat of poultry, eat less preserved food such as barbecued food, sausages and luncheon meat. Milk is rich in calcium, phosphorus and protein. Calcium and phosphorus help strengthen teeth and bones.


Choose low-fat or skimmed milk and milk products (including cheese, yogurt). Try not to use condensed milk.

Oil and Fats

Fat provides energy, maintains body temperature and facilitates absorption of vitamins A, D, E and K. It is also the basic component of cell membranes and hormones.


Choose pure vegetable oil e.g. rapeseed oil, olive oil and avoid animal oil. Although pure vegetable oil does not contain cholesterol, but its fat and calories are equivalent to that of animal oil and will cause obesity if taken in excess.


Maintain balance of body fluid, but may cause high blood pressure if taken in excess.


Provides calories, but contains little nutrients. May cause obesity and tooth decay if taken in excess.


Do You Know

Vitamin C gets destroyed during cooking due to heat.

We should therefore eat raw fruits and vegetables to get adequate vitamin C


Malnutrition: A person is said to be suffering from malnutrition if he isg (eating food having only one component i.e. rice, chapattis and potatoes only

Such people suffer from deficiency diseases.

Under nutrition: If a person is not getting sufficient amount of food as perhis hunger, he is suffering from under nutrition.



The three main types of food have specific chemical tests that enable us totake any piece of food and test to see if it contains protein, fat or carbohydrate.

We can test for protein using the Biuret test. This involves adding the pieceof food to a copper sulphate solution with a little sodium hydroxide added.

The light blue colour changes to purple if proteins are present.

Food contains fat if a white emulsion (tiny droplets of fat in water) is made after mixing the food with water and ethanol. This is called the alcohol emulsion test.

Carbohydrates come either as starch or sugars.

If you add a few drops of iodine to food it will go blue/black if starch ispresent.

For sugars we can use Benedict's test. Here we boil up some of the food withBenedict's solution; the blue colour will change to an orange if sugars arepresent.



They occur mainly due to the deficiency of one or more nutrients in the dietover a long period of time. For example, wheat is rich in carbohydrates, butpoor in nutrients like proteins and fats. Too much intake of wheat productsresults in a deficiency of proteins and fats, which reduces growth.



All our energy requirement comes from carbohydrates and fats. People with carbohydrate deficiency are weak and lack stamina to do work.

Too much of carbohydrate is not good for our health. The extra carbohydrateis stored as fat in the body. This leads to obesity and such people to prone toheart diseases.

A fatty lady  



Growing children need more protein for their growth and development and sothey suffer maximum from this disease. This happens in two ways:

(1) Lack of proteins or carbohydrates or both in the diet

(2) More intake of carbohydrate than proteins.

This deficiency causes two types of diseases;

(a) Kwashiorkor                (b) Marasmus

Kwashiorkor: This disease is very common among the poor people, beggars and labourers. It makes children restless, miserable and they show stunted growth. Belly protrudes out and legs become long and thin. Hair loses luster.

Marasmus: This disease is very common in infants below one year of age. Itis caused due to under nourishment of proteins and carbohydrates or both. Thechild suffers from digestive disorder and diarrhoea. The child shows retardedmental and physical growth. The skin shows a number of folding and ribsbecome prominent. Face looks thin and eyes get sunken.

Prevention and control: a protein rich diet which includes soya bean, jaggery, wheat, gram, meat can cure the disease.




1. Rickets and osteomalacia

This is caused due to deficiency of vitamin D, calcium and phosphorusin the diet. Rickets occur in small children while osteomalacia occurs inadults. Symptoms include soft bones with deformities. Legs become bowshaped and chest becomes pigeon shaped. Loss of teeth may also occur.

In osteomalacia bones become soft and tend to fracture easily.

Prevention: Cure lies in consuming animal fats, butter, ghee, milk andeggs. One should also take in plenty of sunlight to produce vitamin D.

2. Anaemia

This is caused due to deficiency of iron in our diet. The iron content inblood decreases due to which the blood is unable to carry full supply of oxygen to the cells of the body. Person suffering from this disease lookspale, gets tired easily and suffers from loss of appetite.

Prevention: The disease can be cured by having a diet rich in iron suchas green leafy vegetables, eggs, meat, wheat sprouts, turnip etc.



3. Goitre

It is caused due to deficiency of iodine in the body. Iodine is necessary for the formation of thyroxin, a hormone of thyroid gland. This hormonecontrols the growth and metabolic activities of our body. Symptomsinclude swollen thyroid gland, retarded physical and mental growth.

Prevention: Consumption of iodized salt and fish can help in reducing the incidence of goitre.



1. Night blindness

Caused due to deficiency of vitamin A. Person suffering from this diseasecan't see in dim light. Drying of eye balls occurs as the tear glands donot produce tears.

Vitamin A-rich diet

Prevention: Can be prevented by having vitamin A rich food like animalfats, liver, kidney, egg, milk and butter.


2. Beriberi

Caused due to deficiency of vitamin \[{{\text{B}}_{\text{1}}}\] (thiamin). Patients suffering fromthis disease show extreme weakness and swelling and pain in legs. Thereis loss in appetite and shortness of breath. Can lead to enlarged heartand paralysis.

Prevention: Can be cured by having vitamin \[{{\text{B}}_{\text{1}}}\] rich food like cereals, wheat, cabbage, carrots, milk and spinach.


3. Scurvy

Caused due to deficiency of vitamin C.

Symptoms include general weakness, pain in the joints, reduction in bodyweight, anaemia, loss of appetite and delay in healing of wounds.

Prevention: Can be cured by having vitamin C rich food like oranges, grapes, lemon, fruits, tomatoes, mangoes, amla and all green leafyvegetables.


Do You Know

Scurvy was common among sailors in ancient times. In the 18th century, James Lind found out that eating citrus fruits reduced the occurrence of scurvy in sailors.

Deficiency of water: Excess loss of water leads to dehydration in the body.

The body becomes weak. To recover from dehydration the patient is given ORS (oral rehydration solution).


Concept Map


Other Topics

Notes - Components of Food

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