The liver is a critical body organ that functions as a repackaging and distribution plant. Foods contain nutrients that go to the liver and get repackaged into useful forms and then distributed to other parts of the body. For example, brain cells need a constant supply of the sugar glucose. The liver attempts to ensure there is enough of this “brain candy” in the blood at all times. In addition, the liver is constantly adjusting the level of fat components, proteins and amino acids that are in the blood and used by all other parts of the body.

Foods also contain a variety of naturally occurring toxic components that the liver usually can detoxify into harmless molecules that can be disposed of through urine or feces. Similarly, the liver handles most food additives that could be toxic if consumed excessively.

QUESTION: How does the liver handle drugs?

ANSWER: The liver is responsible for converting most drugs into harmless molecules that can be passed into the urine and eliminated from the body. This is why most drugs need to be taken periodically in specific doses to maintain effective blood levels of the drug. If liver function is compromised by disease or malnutrition, it can be easier to overdose on certain types of drugs. For example, someone with an iron deficiency can have negative side effects from normal doses of a medication if the iron-dependent detox system of the liver is hindered.

The liver is also the main site for dismantling the alcohol molecule for use as energy (calories); however, it can do this only so fast. When the capacity to handle alcohol is exceeded, blood-alcohol levels rise and can damage the liver over time., especially if liver function is compromised by disease.

Q: What health problems compromise liver function?

A: There are many things that can damage this sturdy organ. Excessive alcohol consumption gradually causes fat to accumulate in the liver, leading to liver inflammation, called alcoholic hepatitis. Continued high alcohol consumption can cause destruction or scarring of liver tissues, leading to irreversible cirrhosis of the liver.

A somewhat related condition is called nonalcoholic fatty liver disease. As the name implies, the liver accumulates excessive fat even without excessive alcohol consumption. Although the causes of this NAFLD are not entirely clear and may not be the same in everyone, it is known that dietary deficiencies of choline and/or protein contribute to fat accumulation in the liver. Typical treatment involves weight loss if the person is overweight, but it also is important to make sure that protein intake is adequate and that the diet contains a good source of choline, like eggs.

Five known virus types cause hepatitis: A, B, C, D and E. Immunizations are widely available for A and B, and the B vaccination protects against D. Type E, acquired from contaminated water or food, has effective vaccines, but they are not widely available.

Hepatitis C is currently a major concern, especially for baby boomers (born between 1945 and 1965). Prior to 1992, donated blood was not screened for the hepatitis C virus, and baby boomers are five times more likely to have been exposed. The virus slowly destroys the liver over decades (without early symptoms). It is recommended that all in this age group get tested, because early detection leads to more successful treatment.

Alan Titchenal, Ph.D., C.N.S., and Joannie Dobbs, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. Dobbs also works with University Health Services.