Food is any material consumed to supply nutrients to an organism for growth, health, or maintenance. In simple terms, food is any food capable of converting into other stuff, in the process of being consumed. Usually food is of animal, plant or even fungal source, and consists of essential nutrients, including protein, carbohydrates, vitamins, or other minerals.
Generally, people get food from five main food groups: animal-derived foods, plants, fungi, and bacteria. Plants, especially vegetables and fruits, are rich in essential nutrients; animal-derived foods include meat and milk products, which are rich in protein but lack in other essentials nutrients, and bacteria, which are found in feces and on the skin. Fruits and vegetables are a major source of nutrition for the majority of people, although these foods may lack certain important ingredients that are crucial for proper nutrition.
The best diet for overall nutrition involves a combination of all five food groups, with some variation in proportion to one another. This allows people to receive all of the beneficial effects of each group without feeling starved, as occurs when a person eats mainly animal-derived foods and lacks other kinds of nutrients. The American Dietary Association recommends that Americans eat foods from each of four groups, with a small balance of unprocessed foods. This dietary plan is the foundation for healthy diets throughout the world.