Food is any material consumed in order to provide nutrition to an organisms living in it. In essence food is the total product of living organisms which consists of proteins, carbohydrates, fat, vitamins, minerals or both. There are different types of food, for example: plant foods like fruits and vegetables, animal foods like meat, milk and eggs, and chemical foods like fertilizers, medicines, pesticides and cleaning agents. The type of food that an organism requires depends on its physiological processes, the environment it lives in, its ability to digest food, etc.
The food items are classified into two broad categories according to their chemical constituents: primary food and secondary food. Primary food is generally known as the major source of energy or main course food; it includes all the substances that an organism needs to grow and develop normally, including: water, protein, mineral salts, fat, vitamins and other important nutrients. Secondary food is a mixture of primary food with different nutrients; this mixture of primary food and different nutrients can be added to primary food to improve its nutritional quality.
Fruits and vegetables are considered to be good for health because they are rich in fiber, vitamins and other important nutrients, and have very low calories. Most people take fruit and vegetable juices regularly to keep their body fit and healthy. Many researches show that vegetables have a great amount of Vitamins A, C and E, beta carotene, fiber, potassium and calcium which help to strengthen the walls of our arteries and reduce the risk of coronary diseases. Some researches also reveal that fruits and some vegetables help to reduce the risk of stroke and other cardiac diseases. Therefore, it can be said that fruits and vegetables are indispensable for a healthy and long life.