1. To get energy 

The energy necessary for the body is mainly obtained from carbohydrates and fats in our food. 

2. For the growth of the body 

Protein in the food helps the body to grow. Apart from this vitamins and minerals are also important for the growth of the body. 

3. To be safeguarded from diseases 

Vitamins and minerals mainly help us to safeguard ourselves from diseases. 

The nutrients necessary for these activities are present in food. 

To receive the proper nutrition we should add different types of food to our meals. Food can be categorized under six groups. 

1. Grains (cereals) and tubers (yams) 

2. Vegetables 

3. Fruits 

4. Meat, fish, eggs and pulses 

5. Milk and milk products 

6. Food containing oils and sugar 

Different categories of food, their main nutrients and their functions are shown below. 

1. Nutritional value 

Nutritional value of food depends on the quality and the quantity of nutrients present in the food and this could increase or decrease depending on many factors. 

2.Variety 

Adding different types of food to our meals or the same food prepared in different ways can provide variety and could make nutrients easily available for the body.

E.g. 

● adding food of different colours and flavours, 

● taking five portions of fruits and vegetables of different colours daily, 

● preparing food in different ways (frying fish, ambul thiyal, fish curry)  

Let us put it into practice 

Line up different coloured fruits and vegetables. Find out methods of including these in your diet with their natural colours. 

3. Sufficient quantity 

The quantity of food intake differs from person to person depending on their Body Mass Index (BMI), age, sex, activeness and health condition. 

Three major meals and two minor meals are sufficient for a day’s intake of nutrients by a person. By taking five types of vegetables or fruits in a day you can obtain different nutrients such as vitamins and minerals. 

The food taken from each food group should be proportionate to each other. A simple method to follow in your day to day life is to serve proportionately, by dividing your meal as follows in the food plate. 

Food plate 

The meal should comprise; 

• Starchy food (yams, grains) - about 1/2 of the plate 

• Food with proteins (meat, fish, eggs) - 1/4 of the plate 

• Vegetables and fruits - 1/4 of the plate 

In addition you should take; 

• Milk or dairy products - 2 portions per day (1 portion =150 ml fresh/ powder milk = 1tub of yogurt/curd = piece of cheese) 

• Oil and sugar - a little amount should be added. 

4. Natural condition 

Natural food means food with minimal addition or no addition of preservatives, colouring or chemicals. Natural food is high in nutritional value. In addition to natural vitamins they also contain dietary fibre as well. Processed foods are not favourable to the health, e.g. sausages, french fries, artificial drinks. 

5. Freshness 

Fresh fruits and vegetables contain more vitamins and minerals. As time passes the colour, taste, and smell of the food changes and with that the desire to eat them also declines. Nutrients like vitamins can be destroyed when food gets stale. Therefore as time passes the nutritional value in food also decreases. 

6. Cleanliness 

It is very important to safeguard the cleanliness of food when manufacturing, storing, transporting, cooking and consuming. Adding of agrochemicals and chemical fertilizers should be minimised when growing plants for food. It is very important to safeguard food from insects such as cockroaches and rats during storage. This is because these animals can spread germs that can cause disease. In transportation food should be packed and safeguarded without germs entering and food getting spoilt. It is essential to wash both hands with soap and water before preparing or consuming meals. Fruits and vegetables should be washed well, before consumption. 

7. Food hygiene 

Food hygiene means the use of proper methods when choosing, preparing and serving food in order to avoid sicknesses. This is important for making sure that food is suitable for consumption. Table 7.2 explains how ‘hygienic food’ can be chosen. 

Let us put it into practice 

According to races, areas and different functions, food varieties differ. Find out those types of foods and how the nutritional value is preserved in above mentioned varieties. 

There are special foods existing from the ancient times. There are many healthy foods prepared through experiences in the past. 

1) The use of mixed food to enhance nutritional value. E.g. types of food like hath maluwa, green gram milk rice, mixed green leaf mallum, pongal, sambar, buriyani, etc. 

2) We can mix some substances to the food to increase absorption of nutrients. E .g. adding lime juice to green leaf mallum. 

3) Using natural fertilizers when cultivating crops. E.g. animal excreta, dry leaves. 

4) Using natural methods of pest repellents instead of chemical insecticides. E.g. the juice obtained from margosa seeds mixed with water can be used as an insecticide growing marigolds – the smell of this flower repels insects. 

Nutritional problems occur when the necessary nutrients are received either in reduced amounts or increased amounts than the body requires. This is known as malnutrition. 

Undernutrition 

Undernutrition conditions such as stunting, wasting or underweight can occur, due to lack of macro nutrients such as carbohydrats, fats and proteins necessary for the body. 

• Not having the suitable height for the age is called Stunting. 

• Not having the suitable weight for the height is called Wasting (Wasting can be determined by the use of Body Mass Index - BMI). 

Problems faced due to undernutrition 

• Contacts communicable diseases easily 

• Slowing down of physical growth 

• Impaired concentration 

• Impairment of education 

• Reduction of participation in sports activities. 

Overnutrition 

If more macro nutrients such as carbohydrates and fats are taken than the body requires over nutritional conditions can occur. 

This can take two forms; 

• When the weight is higher than required for the height, the result is overweight 

• Excessive weight increase than appropriate for the height is called obesity. 

In the first lesson we learnt to identify the nutritional status using BMI and height chart. 

Let us Learn More 

• Obese individuals are more prone to develop non-communicable diseases such as diabetes, high blood pressure, heart diseases and strokes. 

• To prevent being overweight and obese one should engage in exercises, avoid food with flour, oily and sugar containing foods. 

Micronutrient deficiency states and steps that can be taken to prevent them 

Let us put it into practice 

Find and diagrammatically present different methods that can be used to purify water before drinking. 

Now we know.... 

Food is one of our basic needs. Obtaining energy for the body, growth of the body and protection from diseases are functions of a healthy meal. 

While food can be categorized under six main groups, their nutrient composition differs from each other. A healthy meal consists of all of them in correct amounts, will provide the body with all the required nutrients. The required amounts can differ from person to person. 

Food provides five nutrients and they are carbohydrates, proteins, fats, lipids, vitamins and minerals. These nutrients are divided in to two groups as macronutrients and micronutrients. 

There are certain points you should bear in mind when choosing healthy food, such as nutritional value, variety, sufficient quantity, natural condition, freshness, cleanliness and hygiene of the food. 

Nutritional problems can occur when the nutrients in consumed food are either less or more than required. Main nutritional problems are undernutrition, overnutrition and micronutrient deficiency. 

Let us test our knowledge 

1. Name three main functions of food. 

2. What are the six main categories into which food can be divided? 

3. Name five nutrients we get from food? 

4. What are the factors that will decide the intake of food of a person? 

5. What is the illness that occurs when macro nutrients are taken in excess? 

6. What are the symptoms of iron deficiency? 

7. What food will prevent blindness caused by vitamin A deficiency?