Saturday, June 9, 2012


The foods which we use daily include rice, wheat, dal, vegetables, fruits, milk, eggs, fish, meat, sugar, butter, oils, etc. These different foods are made up of a member of chemical components called nutrients. These are classified according to their chemical composition.
Each nutrient class has its own function, but the various nutrients must act in unison for effective action. The nutrients found in foods are --- carbohydrates, proteins, fats, minerals, vitamins and water. Fiber is also an essential component of our diet. The functions of nutrients are given below.
Carbohydrates: Starch found in cereals and sugar in sugar-cane and fruits are examples of carbohydrates in foods. The chief function of carbohydrates is to provide energy needed by our body. Those not used immediately for this purpose are stored as glycogen or converted to fat and stored, to be mobilized for energy supply when needed.
Fats: Oils found in seeds, butter from milk, and lard from most, are examples of fats found in foods. Fats are concentrated sources of energy, carriers of fast soluble vitamins and a source of essential fatty acids. If excess fats are taken in the diet, these are stored as fat reserves in the body. Energy taken in excess of body needs, is stored as fat in the body.
Proteins: Casein from milk, albumin in egg and gluten in wheat, are examples of proteins occurring in foods. The main function of protein is the building of new tissues and maintaining and repair of those already built. Synthesis of regulatory and protective substances such as enzymes, hormones and antibodies is also a function of food proteins. About 10 per cent of the total energy is supplied by proteins in the diet. Protein, when taken in excess of the body’s need, is converted to carbohydrates and fats and is stored in the body.
Materials: The minerals calcium, phosphorus, iron, iodine, sodium and others are found in various foods in combination with organic and inorganic compounds. Materials are necessary for body – building, for building of bones, teeth and structural parts of soft tissues. They also play a role in regulation of processes in the body, e.g., contraction, clotting of blood, nerve stimuli, etc.
Vitamins: Fat- soluble vitamins A, D, E and K and also water – soluble vitamins C and B group are found in foods. These are needed for growth, normal function of the body  and normal body processes.
Water: We get water in foods we eat and a major part from the water we drink as such and as beverages. Water is an essential part of our body structure and it accounts for about 60 per cent of our body weight. Water is essential for the utilization of food material in the body and also for elimination of food waste. It is a regular of body processes such as maintenance of body temperature.
All individuals need the same nutrients for the same body function. The only variation is in the amounts of each nutrient requirement according to age, size, activity, etc. For example, all persons need energy for work, but a man, who carries loads may need more energy than a man, who works in an office at a desk job.
As you know, we get the nutrients from the foods and the beverages we consume. Most foods contain the nutrients in varying amounts. Let us understand the nutrient composition of the foods we use everyday.
Nutrient density: It refers to the quantity of one or more nutrients supplied by a food in reference to its calorie content. For example, if one compares the protein content of isocalorie portions of dals, bread and milk, one can see that the dal has the highest nutrient density for protein, milk next and bread the least.

Thus nutrient density is an important aspect to be considered in selection foods, especially in diets of children, pregnant women, nursing mothers and in therapeutic diets for patients.

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