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Alcohol Metabolism

Metabolism is a general term applied to the chemical processes that take place within tissues in the body by converting food or liquids to obtain nutrients. When alcohol is ingested, about 20 percent is rapidly absorbed into the bloodstream. The rest is absorbed as it progresses through the gastrointestinal tract. A small amount of alcohol is not metabolized and is excreted through sweat, saliva, urine, and the breath.

In the liver an enzyme known as alcohol dehydrogenase (ADH) converts alcohol to acetaldehyde. This substance is then converted to acetic acid and then metabolizes to carbon dioxide, water, and fatty acids. Some persons, especially those of Asian descent, experience a phenomenon knows as flushing, or alcohol-flush reaction. Flushing is defined as a sudden onset of reddening of the skin, most often seen in the face or neck region. Some who experience flushing also complain of dizziness or nausea and vomiting. This reaction occurs when the production of the enzyme acetaldehyde is insufficient.

A number of factors affect the absorption of alcohol. It must be remembered that alcohol is a lipid that is water soluble, so it can be digested soon after absorption. Alcohol absorption into the bloodstream takes place throughout the gastrointestinal tract. When alcohol reaches the bloodstream, it is very quickly distributed throughout the body.

Body tissues absorb alcohol at different rates. For example, muscle tissue absorbs alcohol more rapidly than fat tissue. This absorption into muscle tissue would mean that less alcohol is circulating in the bloodstream. Since women usually have more body fat than men, they would experience a more profound effect from the same amount of alcohol than would their male counterparts.

Another physical factor is body size. A smaller person feels the intoxicating effects of alcohol more rapidly than a large person. Additionally, since each person has a different metabolic rate, this can be another factor influencing alcohol absorption.

Many variables can affect the rate of alcohol absorption. Carbonated alcoholic beverages or mixers are rapidly absorbed. These may include champagne, sparkling wines, wine coolers, or soft drinks mixed with alcohol. Drinks with a higher concentration of alcohol are also problematic. These include drinks with two or more types of alcohol, such as "ice teas," margaritas, Black Russians, and similar drinks. Use of aspirin products can also increase intoxication by interfering with the breakdown of alcohol.

Drinking alcohol rapidly during a short time span can increase its effects and should be avoided. Consuming alcohol on an empty stomach is a recipe for disaster, as is the ingestion of hot drinks with alcohol such as hot rum drinks or specialty coffee drinks.

Senior citizens are especially vulnerable to alcohol because of age-related changes. These include a marked decrease in body water, loss of muscle tissue, and decreased metabolism. Older people may also be taking medications that can hasten the effects of alcohol.