Food: Functions and Types

Food is indispensable for all the creatures to live. It is impossible for human beings to live without food. The involvement of the food for human beings begins from the embryo phase in the womb; which is essential to lead the healthy and normal life of human beings.

What is Food?

According to the science of Nutrition, all that we eat are not food. For example, a banana stem is formed with cellulose, it is not digested in our stomach. So it is not nutritious. Then, then what is food? The edible items which can produce energy and immunity and helps to grow and develop a living body by its nutrition are called food. It means only if the edible items that helps in body growth, energy production, nutrition, and body corrosion of human being and other creatures are considered as food.[1]

So it is clear that nutrition and food have profound connectivity. Only fulfilling the appetite is not enough; nutritious food elements is a must. And the interaction of nutrients and other substances in food in relation to maintenance, growth, reproduction, health is called Nutrition. It is the resource of materials that organisms and cells require to live.[2]

Nutrition is getting necessary food items from the environment and digesting and absorbing them, then the fulfillment of energy need, developing the immunity of diseases and growth of the body. The organic and inorganic elements in food which provide the vital force of the living body are collectively called nutrients. For example, glucose, minerals, and vitamins, etc. Nutrients do not need to be digested. Living beings get nutrients from food.

Now we all have a clear idea of the edible items that help us to live a healthy life are considered as food.  Every day, we do various physical and mental activities. As a result, our bodies become weak and dilapidated. In that case, food rejuvenates our body. It means food works inside the body. So let us see what does food does to our body.

Functions of Food

“We cannot live without food. Regularly different types of food are necessary for the growth and development of the body, repair, and replacement of worn-out tissue, and for producing energy, etc. Our health depends largely on the quality of the food we take. Food can make differences in our appearance, work, behavior, and standard of life. During the process of respiration, the chemical energy of food is converted into heat energy. every living being takes food from the environment according to its need. Each type of food is a complex chemical compound. This complex food turns into simple food by different types of enzymes in different parts of our digestive system. This process is called digestion. After digestion, foods are absorbed by the protoplasm of the cell; this is called metabolism. After digestion, the undigested part of the food comes out of the body through a special process.”[3]

Functions of Food is as follows:

Food has three main functions in the body. Let’s find them below.

  1. Growth and Development, Repair and Protection of the Body: The growth of the human body is stopped between ages 20 to 25 years. They hardly grow in height after attaining 25 years rather some people gain weight. The body organs grow after consuming the necessary elements from food. The brain of a human being becomes developed completely between ages 2 to 3 years.
  2. Production of Heat and Energy: The human body can be compared with an engine. As energy (e.g. oil, electric, gas) is needed to run an engine, similarly our body needs energy from food which transforms into heat to perform all physical activities. Energy is used to maintain the internal action of the body like breathing, blood circulation, muscle contraction, and extension.
  3. Protecting The Body from Diseases and Making the Body Healthy, Energetic and Active: Our body tissues are involved with metabolism. As a result, tissues are eroded continuously. The body makes new tissues by taking necessary elements from food that are replaced with eroded cells. Several elements of food protect our body directly or indirectly from infectious disease, pollution, and harmful things. But our immune system decreases with less supply of nutritive elements from food.

So, we can see how food works systematically and for this, we can live and lead a healthy life.

Another thing is involved with food. It is the type of food. We need to know how many types of food are available and whether we are able to keep the balance in our diet or not. ‘Types of Food’ will be discussed in the next chapter elaborately but for now, it is discussed here briefly.

Types of Food

Food is divided into three types considering the activity on the body.

  1. Foods for Improving Body Growth, Repairing, and Protection: This class is defined with the foods contains much protein proportionately. Fish, meat, egg, milk, pulses, seeds of bean are great sources of protein.
  2. Foods for Producing Energy: Foods which serves much calorie and energy are classified in this category. Whole unrefined grains and it’s processed food provide more calories and protein as well. Biscuit, cake, noodles; foods or vegetables grow underground; oil, ghee, butter, fat; several types of fruits, date, grapes, banana, jackfruit, nut, sugar, and honey belong to this category.
  3. Foods for Preventing Diseases: Foods that contain vitamins and minerals are considered as disease prevention foods. Fruits, vegetables, milk, egg, animal fat, or oil-like Cod liver oil are in this type which improve your health in many ways.


It is said that Helth is the key to all Happiness. A healthy man is a man of action. And it is not possible to do anything properly without physical fitness. Who are lazy, do not work, may suffer from inferiority complex, and do not get any mental peace. To them everything is meaningless. So we need to be fit and healthy beyond everything. We must intake food maintaining regularity by understanding the food value to keep our body fit and healthy.


  3. Science, Class-IX and X, NCTB, Dhaka, First Edition-2012, Page No-1.

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