Ethanol is primarily oxidized to acetaldehyde in the liver by alcohol dehydrogenase, which also catalyzes oxidation of other alcohols in the liver. However, the liver is a very important organ in many other respects, from supplying the body with energy to detoxifying the bloodstream. In addition to alcohol, many other common drugs, for example acetaminophen, can harm the liver.

Do we know how liver and other alcohol related health problems are caused?

This study put that mechanism under question. Is acetaldehyde directly involved?

Importance of liver in alcohol metabolism

Much of the metabolism of alcohol takes place in the liver. However, the enzyme responsible for this (alcohol dehydrogenase- see Figure 3) may have evolved to break down various alcohols in foods, such as ethanol, methanol, and ethylene glycol and the alcohols produced by bacteria in the digestive track. (Begun 1997) In fact, a common treatment for methanol ingestion (an ingredient in antifreeze) is ethanol. The metabolite produced from methanol by alcohol dehydrogenase is formaldehyde, a potentially toxic compound. Because ethanol is preferentially broken down by alcohol dehydrogenase, the methanol has a chance to be harmlessly secreted without being converted to toxic formaldehyde on a large scale.

Other Important Functions of the Liver

The liver makes and exports energy rich compounds such as glucose and ketone bodies for the rest of the body, providing energy for other tissues when glucose supply is low. This ensures that essential organs like the brain continue to function under a varied set of conditions. Alcohol oxidation consumes NAD+, stalling gluconeogenesis in the liver. Since the liver uses that process to export energy or sugars to the blood, inhibition of this process leads to lowered blood sugar and a hangover. (Wikipedia. “alcohol dehydrogenase.”) The live receives most nutrients before other areas of the body. The liver then decides their fate—shuttling them to the most needed processes or filtering them out or detoxifying chemicals that could otherwise have disastrous effects.

Tylenol and Your Liver

Other chemicals can also harm the liver. Consider, for example, the acetaminophen in Tylenol used to treat a hangover which by itself in excess amounts can cause liver damage. It is increasingly harmful when combined with excess drinking potentially leading to death in the future. These combined effects, although they may seem mild initially, can potentially add up over various activities and substances.

As you can see, the liver is a very important organ. Liver damage from excess drinking or other causes can greatly harm many other aspects of your life, from your ability to take Tylenol for a headache to dying from accumulated toxins.

Read on to see about recent research into acetaldehyde's harmful effects.

Figure 7a: Liver

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Figure 7b: Liver Diagram

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Figure 8: Glucose as an Important Biochemical Energy Source

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Figure 9: Tylenol as Potentially Harmful to the Liver

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