Food is any material eaten to supply nutrition to an organism. Food is normally of animal, plant or fungi origin, and usually contains necessary nutrients, including proteins, carbohydrates, vitamins, or even minerals. Food helps to maintain health by providing the organisms with the energy needed to grow, develop, reproduce, heal, and survive. The nutritional value of food is usually in the form of essential fatty acids, which are a source of vitamin D; fat, protein, and carbohydrates; and other nutrients.
The amount of food that an individual eats and the frequency of food eaten vary, depending on the type of organism to which it belongs and the requirements that it has for growth and development. Plants, animals, fungi, bacteria, and other organisms eat a variety of food types, including carbohydrates, protein, essential fatty acids, vitamins, and minerals. Fungi and bacteria in turn produce important substances called nitrogenous waste products, which are then eaten by other organisms. Human beings eat a wide range of food types, but the major dietary components are carbohydrates, protein, fat, and vegetables.
The nutritional value of food is not the only factor that contributes to good health. It is also important to choose food in appropriate proportions, especially if one is a vegetarian or lacto-ovo vegetarians (people who eat dairy products). The types of food and their proportions depend on the physiological makeup of an individual. Foods that are nutritionally adequate may not provide all the nutrients needed by people to survive and thrive, so individuals must eat a wide variety of foods to obtain a balanced diet.