Nutrition in organisms

Food is the basic necessity of man. It is a mixture of different nutrients such as carbohydrate, protein, fat, vitamins and minerals. These nutrients are essential for growth, development and maintenance of good health throughout life. They also play a vital role in meeting the special needs of pregnant and lactating women and patients recovering from illness.

Nutrition is the sum of the processes by which an organism takes in, metabolises and utilises food substance for its various biochemical activities.Nutrition is the process of taking food by an organism and utilization of food for energy. This is a vital process which helps living beings to obtain their energy from various sources. Nutrients are the substances which provide nutrition. All living organisms need nutrients for proper functioning and growth.

Nutrients are the organic or inorganic substances which help in our survival and in maintaining proper health. A nutrient supplies energy to the body, builds and repairs body tissues and regulates the body metabolism.

On the basis of quantity required by the body, nutrients are classified into two categories :

(i) Macronutrients (ii) Micronutrients

Macronutrients:- Nutrients that are needed in large amounts are called macronutrients . There are three classes of macronutrients: carbohydrates, lipids, and proteins. These can be metabolically processed into cellular energy. The energy from macronutrients comes from their chemical bonds. This chemical energy is converted into cellular energy that is then utilized to perform work, allowing our bodies to conduct their basic functions. A unit of measurement of food energy is the calorie.

Micronutrients :-nutrients that are required in small amount, such as Vitamins and minerals form only a small fraction of the total weight of the food.

On the basis of physiography food can be classified as

 Energy yielding foods

 Body building foods:

 Protective and Regulatory foods:

A balanced diet is one that contains all essential nutrients in suitable proportion and amount to provide necessary energy and keeps the body in a healthy state. A balanced diet has the following qualities :

 it meets the nutrient requirement of the body,

 it consists of different types of food items,

 it provides adequate amount of energy,

Special circumstances where the Balanced diet is condition specific:-

Nutritional needs for growing children Growing children need more food in proportion to their body weight. They need –

(i) extra protein to make new tissues for growth, (ii) more calcium and phosphorous for formation of bones and red blood cells, (iii) vitamin A for development of healthy eyesight, (iv) vitamin C for general health, and (v) vitamin D for healthy bones.

Nutritional needs for persons in different occupations :-Persons doing hard physical work like rickshaw pullers, labourers, carpenters, mill workers. require food which is rich in energy (carbohydrates and fats). Similarly, athletes also require diet of high energy value. 3. Nutritional needs during pregnancy and lactation :-A pregnant women has to feed the developing embryo, therefore, she has special need for extra nutrients.

The pregnant women and lactating mothers should take,

(i) extra protein for tissue growth (ii) more calcium and phosphorus to form bones of the baby (iii) more iron for making sufficient blood of the baby (iv) more carbohydrates for herself because extra energy is required to carry out all the building processes linked with embryo. 4. Nutritional needs depending upon the state of health :-The persons recovering from illness need more proteins, minerals and vitamins in their diet to repair the damage caused by the ailment. If there is loss of blood due to surgery or an accident the patient needs more of proteins and iron to make up for the loss of blood.

Modes of Nutrition:-

Living organisms show two modes of nutrition:

(i) they prepare their own food, and (ii) they take in ready-made food, either from plants (fruits and vegetables) or from animals (milk, meat and eggs).

Green plants can make their own organic food from simple substances like water and carbon dioxide through the process of photosynthesis and are called autotrophs (auto : self; trophos : feeding). But the non-green plants and other organisms which cannot prepare their own food and obtain nutrition from green plants are called heterotrophs (heteros : different).

Carbon, hydrogen and oxygen are the main elements in carbohydrates, fats and proteins. In addition to these three elements, plants need a variety of elements for their survival. These are generally referred to as mineral elements. They are absorbed by the root system of plants in the form of their salts.

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