Introduction To Nutrition
Food is any material consumed in order to provide nutritional support to an organisms. In humans, food is generally of animal, plant or fungus origin, and consists of nutrients, including proteins, vitamins, carbohydrates, or fats. Some plants secrete chemical substances into the soil in order to provide nutrition to the plants when they become ill or are unable to grow due to weather conditions or disease. Many animals secrete pheromones into the soil, which is used by insects as a signal to seek out food. Animals and insects also consume plant foods to survive, as well as to feed themselves.
The majority of ingested nutrients are immediately metabolized by the body and then released as waste in the form of fats, protein, carbohydrates and vitamins. Some food can be stored as fat if it is taken in large quantities for prolonged periods of time. Fat is necessary for energy production during rapid physical exercise or extended exercise, but it is also stored as body fat when not used. Therefore, it is important to consume a diet rich in calories in order to provide energy to maintain normal body function and proper weight.
A variety of foods are available to us each day. A wide range of food is available in grocery stores, health food stores, markets and from mail order catalogs, both fresh and dried, as well as processed. It can sometimes be difficult to decide what to eat. Some people prefer one type of food over another, while other people may not have a preference at all.