Water is considered the most important nutrient because of its many diverse functions within the human body. A nutrient can be defined as an element from food or beverage that performs either a sustaining or metabolic function when consumed. Water is vital to the sustainability of human life.
Essential nutrients are supplied by outside sources in the form of food or drink because they cannot be made by the body in sufficient amounts. The human body cannot produce water, yet it requires a great amount of water to function. Therefore, water is considered to be a nutrient. Most people cannot survive more than a week without water, making it the most essential nutrient to the human body.
Comprising approximately 60 to 75 percent of the human body, water serves many diverse functions. For example, it transports other nutrients and elements throughout the body. It helps excrete waste from the body. Water acts to lubricate body tissues. It is a key component of the digestive system, moving matter through the digestive system and providing salivary juices and mucous to help breakdown food. As a key component in many chemical reactions within the body, it allows for the digestion of proteins and carbohydrates, helping convert them into usable matter that can be absorbed by the body. Furthermore, water helps regulate body temperature.