FOOD AND NUTRITION ( SCIENCE )

The process of intake of any external source of energy or food is called nutrition. All living organisms require energy, but they get it from different sources. Some organisms utilize simple inorganic sources such as, carbon dioxide and water, whereas the other organisms utilize complex substances. These complex substances are broken down into simpler ones before they can be utilized by various life processes for the growth and repair of the body. All the varied sources of energy, that any living organism consumes, are always broken down or built up into a uniform source of energy that can be used for sustaining various life processes. There are seven major classes of nutrients that the body needs: carbohydrates, fats, proteins, vitamins, minerals, fibers and water

Carbohydrates:
These are the body’s main source of energy. The three different kinds of carbohydrates are starch, sugar and fibers. Plant foods like cereals, bread, rice, pasta, potatoes, plantains and corn are good sources of starch. They give us the energy we need to do daily activities. These starchy foods give us important vitamins and minerals, too.

Fats:
Fat is a nutrient that is an important source of calories. One gram of fat supplies 9 calories - more than twice the amount we get from carbohydrates or protein. Fat also is needed to carry and store essential fat-soluble vitamins, like vitamins A and D. There are two basic types of fat. They are grouped by their chemical structure. Each type of fat is used differently in our bodies and has a different effect on our health.
Fat is found in many foods. Some of the fat that we eat comes from the fat we add in cooking or spread on breads, vegetables or other foods. A lot of fat is hidden in foods that we eat as snacks, pastries or prepared meals.

Proteins
These are necessary for the growth of the cells. It also repairs or replaces healthy cells and tissues.

Protein is made of chains of amino acids. Amino acids are the building blocks of protein. Our bodies can make most of the amino acids. Most foods that are obtained from animals, such as fish, chicken, beef, pork, eggs, milk, cheese, and yogurt contain all of the essential amino acids. They are known as “complete” proteins. Plant foods, such as rice, dried beans, peas, lentils, nuts, seeds, wheat, oats, corn, may be low or lacking in one or more of the amino acids. They are considered to be incomplete proteins.

Vitamins
These are the organic compounds obtained from the food in minute quantity. They must be supplied from external sources and perform specific functions. On the basis of their solubility, vitamins are divided into two categories:
• Fat soluble vitamins – Vitamin A, D, E, and K
• Water soluble vitamins – Vitamin B complex, and C

Vitamin A: It is also known as retinol. It is manly found in animal sources such as cod-liver oil, milk, butter, ghee, egg, fish, etc. In plant sources, vitamin A is mainly found in carrot, tomatoes, leafy vegetable, papaya, etc.

The deficiency of this vitamin can cause nightblindness.

Functions
Vitamin A is essential for growth.
It is main component of rhodopsin, hence it is essential for night vision.
It controls the action of bone cells.

Vitamin D: It is also known as calciferol. It is mainly found in animal sources such as cod liver oil, butter, milk, ghee, egg, etc.

Functions
It promotes calcium absorption from the intestine.
It helps in the development of new born.

Vitamin E: It is also known as tocopherol. The main animal source of this vitamin is egg, fish, meat, etc. The plant sources include vegetable seed oils sucha s wheat, soyabean, corn, etc.

Functions
It has antioxidative properties. It mainly prevents unwanted oxidation the body.
It is required for normal functioning of muscles.

Vitamin K: It is also known as phylloquinone. The main plant sources of this vitamin are cabbage, spinach, tomatoes, etc.

Functions
It helps in the maintenance of normal prothrombin and factor VII in the blood. Thus it takes active part in normal coagulation.

Vitamin B complex: It includes vitamin B₁ or thiamine, B₂ or riboflavin, B₃ or pantothenic acid, B₅ or niacin, B₆ or pyridoxine, B₁₂ or cyanocobalamin.

The main source of this vitamin are cereals, pulses, nuts, and green vegetables.

Functions:
It is essential for normal growth
It is essential basic reactions of metabolism
It helps in the formation of fat from carbohydrates.

Vitamin C: It is also known as ascorbic acid. It is mainly found in citrus fruits such as amla, tomato, papaya, etc. It is also found in fresh vegetables such as cabbage, spinach, cauliflower, beans. Etc.

Functions:
It is essential for proper functioning of the formative cells of various tissues
It plays a key role in wound repair.