Specific role of nutrients:
Each nutrient will have a specific role or specific function to perform in the body. Depending upon the functions they perform, nutrients are categorized into two different categories.
- Proximate principles: carbohydrates, proteins and fats or lipids
- Protective principles: vitamins, minerals and water.
(I) Proximate principles :
- Carbohydrates: They make up the bulk of our diet. They are the chief sources of energy. About 70% of energy requirement for body functions are obtained from carbohydrates. Energy is produced by the oxidation of carbon hydrogen animal cells using oxygen. Carbohydrates also help in the utilization of proteins and fats. Carbohydrates when consumed in excess are converted into fats to be used when needed.
1 gram of carbohydrate contains 4 kilocalories of energy.
- Starch and sugars like sugar cane, jaggery, sago etc.
cereal grains like rice, wheat, jowar etc.
- Proteins: Proteins are the major source of building materials for the body. They play an important role as structural constituents of cellular membrane and function in the maintenance and repair of the body tissues. Excess of proteins not required for building may be used as a source of energy.
1 gram of protein contains 4 kilocalories of energy.
- Proteins are found in both animal as well as plant Kingdom.
- Animal sources: milk, meat, milk products, fish, poultry, eggs etc.
- Plant sources: pulses, nuts, cereals etc.
- Fats or lipids: Fats are most concentrated form of energy in the food. When compared to carbohydrates fats contain less percent of oxygen and more percent of hydrogen and consequently on oxidation, yield more energy generally about 30% of human energy requirements are made by fats. When excess energy is supplied to the body it is stored as fat in the adipose tissues.
1 gram of fat contains 9 kilocalories of energy
- Nuts, butter from milk, oil, ghee etc
- The adipose tissues of animal consist mainly of fats.
- Vitamins: Vitamins are accessory nutrients. They are required for proper utilization of the bulk food of the diet. Vitamins are involved in small quantities in the regulation of body processes. They are constituents of enzymes which functions as catalyst for many biological reactions within the body.
Specific role of nutrients:
- Vegetables and fruits are good sources of vitamins.
- Wheat is an excellent source of vitamin b. They are found in milk and milk products, liver, egg etc.
- Minerals: Minerals also act as catalyst for many biological reactions within the body. There other functions include the building of bones and other structural parts of the body, muscular contraction, transmission of nerve impulse, digestion and utilization of nutrients in food. Some minerals like calcium, Iron, potassium, magnesium are required in large quantities. While others like Zn, Co, I, Mn, Cu Are required in less quantities .
Found in both plant and animal foods.
(f) Water: Water a second after oxygen important for the body. It is an ideal medium for transporting dissolve nutrient and waste throughout the body.
- Apart from consumption of water such as body needs of water are supplied by the food we consume.