While the liver serves a variety of functions, the most crucial is its role in the body's metabolism. There is no organ that is more important to healthy metabolism than the liver - in many ways, it is as central to metabolism as the heart is to the circulation of blood. The liver plays a critical role in four key areas of metabolism: fuel management, nitrogen excretion, the regulation water distribution between the blood and tissues, and the detoxification of foreign substances.

Because of the crucial importance of healthly metabolism to overall health, diseases of the liver, such as hepatitis C, can be devastating, leading to fatigue, malaise, and even to death.