Food is a more basic need of man than shelter and clothing. It provides adequately for the body's growth, maintenance, repair and reproduction. Food furnishes the body with energy required for all human activities, it provides materials required for the building and renewal of body tissues and the substances that act to regulate body processes. An individual food, such as milk, may fulfill all these functions or, as in the case of sugar, nay one function. However, all the above functions of food must be served by the diet in order to maintain the body in good health. Most foods fulfill more than one function as they are complex mixtures of a number of chemical substances.
Food are composed of dozens or even hundreds of different kinds of substances- the 'nutrients,' which when consumed in adequate amounts, fulfill all the functions of the body. Six general classes of nutrients found in all foods are carbohydrates, fats, proteins, vitamins, minerals and water.
Carbohydrates make up the bulk of our diet. They are our chief source of energy. About 70 percent of the energy requirements for all body functions is obtained from carbohydrates. Energy is produced by the oxidation of internal burning of carbohydrates in the 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.
The main sources of carbohydrates in the diet are starch and sugar. The sources of the former are mainly cereal grains such as wheat, rice, etc. or tubers such as potato. sweet potato, cassava and those of the latter are sugarcane and fruits.
Fats or lipids are the most concentrated form of energy in the food. They furnish more than twice the number of calories per gram furnished by carbohydrates or proteins.When compared to carbohydrates, fats contain a less percentage of oxygen and more of hydrogen, and consequently on oxidation yield more energy. Generally about thirty percent of human energy requirements are met by fats. When excess energy is supplied to the body, it is stored as fat.
Fat are abundant in both plant and animal materials. In plants they may be confined to the cytoplasmic or may also be present as reserve material. The first content of fruits (except avocado and olive) is poor. Fat up to about fifteen percent is present in the germ of cereals. Nuts, such as groundnuts, are rich sources of fats. Butter from milk is an important source of fat. The adipose tissue of animals consists mainly of fats.
Proteins are the major source of building material for the body. They play an important role as structural of cellular membranes and function in the maintenance and repair of body tissues. Proteins also function as bio catalysts. The food value of the protein depends upon the nature and content of the amino acid, which are its structural units. The excess of protein not required for building may be used as a source of energy.
Proteins are found in both animal and plant tissues. Meat, fish, poultry, eggs, milk and cheese are very nice sources of protein foods from animal sources. Pluses and cereals contain considerable amount of storage proteins. Soybean contains over 40 percent protein on dry weight basis. Nuts and seeds are also good sources of proteins. Starchy vegetables contain up to two percent protein. Other vegetables and fruits are poor sources of proteins.
Vitamins are found in plant and animal tissues. Their content in plant tissues varies widely depending upon the growing condition, stage of maturity, handling, processing and storage. The are not uniformly distributed in plant tissues. Vegetables and fruits are good sources of vitamins. Wheat is an excellent source of B vitamins, but the bran and germ, containing the bulk of these nutrients, are usually removed during processing. Since vitamins are simple organic substances they are easily synthesized and the synthetic vitamins are added to enrich of supplement those found in food products.
Minerals are found in foods from animal and plant sources. The mineral content of plant foods varies depending upon the mineral elements present in the medium of cultivation. The distribution of a particular mineral element varies in different tissues. Minerals, as vitamins, are added to food to enrich it.
Water is second only to oxygen in importance for the body. It is and ideal medium for transporting dissolved nutrients and wastes throughout the body. Apart from consumption of water as such, body needs of water are supplied by the food we consume. Some foods contain a high percentage of water. Apart from this, oxidation of carbohydrates, fats and proteins in the body yields water.
In addition to the above nutrients foods contain enzymes which function as catalysts in chemical reaction, coloring material and flavor compounds.
Food are composed of dozens or even hundreds of different kinds of substances- the 'nutrients,' which when consumed in adequate amounts, fulfill all the functions of the body. Six general classes of nutrients found in all foods are carbohydrates, fats, proteins, vitamins, minerals and water.
Carbohydrates make up the bulk of our diet. They are our chief source of energy. About 70 percent of the energy requirements for all body functions is obtained from carbohydrates. Energy is produced by the oxidation of internal burning of carbohydrates in the 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.
The main sources of carbohydrates in the diet are starch and sugar. The sources of the former are mainly cereal grains such as wheat, rice, etc. or tubers such as potato. sweet potato, cassava and those of the latter are sugarcane and fruits.
Fats or lipids are the most concentrated form of energy in the food. They furnish more than twice the number of calories per gram furnished by carbohydrates or proteins.When compared to carbohydrates, fats contain a less percentage of oxygen and more of hydrogen, and consequently on oxidation yield more energy. Generally about thirty percent of human energy requirements are met by fats. When excess energy is supplied to the body, it is stored as fat.
Fat are abundant in both plant and animal materials. In plants they may be confined to the cytoplasmic or may also be present as reserve material. The first content of fruits (except avocado and olive) is poor. Fat up to about fifteen percent is present in the germ of cereals. Nuts, such as groundnuts, are rich sources of fats. Butter from milk is an important source of fat. The adipose tissue of animals consists mainly of fats.
Proteins are the major source of building material for the body. They play an important role as structural of cellular membranes and function in the maintenance and repair of body tissues. Proteins also function as bio catalysts. The food value of the protein depends upon the nature and content of the amino acid, which are its structural units. The excess of protein not required for building may be used as a source of energy.
Proteins are found in both animal and plant tissues. Meat, fish, poultry, eggs, milk and cheese are very nice sources of protein foods from animal sources. Pluses and cereals contain considerable amount of storage proteins. Soybean contains over 40 percent protein on dry weight basis. Nuts and seeds are also good sources of proteins. Starchy vegetables contain up to two percent protein. Other vegetables and fruits are poor sources of proteins.
Vitamins are found in plant and animal tissues. Their content in plant tissues varies widely depending upon the growing condition, stage of maturity, handling, processing and storage. The are not uniformly distributed in plant tissues. Vegetables and fruits are good sources of vitamins. Wheat is an excellent source of B vitamins, but the bran and germ, containing the bulk of these nutrients, are usually removed during processing. Since vitamins are simple organic substances they are easily synthesized and the synthetic vitamins are added to enrich of supplement those found in food products.
Minerals are found in foods from animal and plant sources. The mineral content of plant foods varies depending upon the mineral elements present in the medium of cultivation. The distribution of a particular mineral element varies in different tissues. Minerals, as vitamins, are added to food to enrich it.
Water is second only to oxygen in importance for the body. It is and ideal medium for transporting dissolved nutrients and wastes throughout the body. Apart from consumption of water as such, body needs of water are supplied by the food we consume. Some foods contain a high percentage of water. Apart from this, oxidation of carbohydrates, fats and proteins in the body yields water.
In addition to the above nutrients foods contain enzymes which function as catalysts in chemical reaction, coloring material and flavor compounds.