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How the Human Body Processes Alcohol

Everything that people eat or drink needs to be processed in some manner by their bodies. Alcohol is no exception. The way the human body metabolizes alcohol is the same in each person, but there are some factors that can affect the rate at which it happens in different people. Understanding how the body processes alcohol is helpful for people in making decision that will avoid being stopped or arrested for DUI/DWI.

Metabolism Process

Once alcohol enters the body and goes into the stomach, the body begins to process it with an enzyme called alcohol dehydrogenase (ADH). ADH begins to break the alcohol down into acetaldehyde, which the body then turns into acetate.

However, the ADH in the stomach cannot process all the alcohol a person ingests, and the unprocessed alcohol flows through the walls of the stomach and small intestine and into the bloodstream where it is eventually processed through the liver. The liver then begins to break the alcohol down with an enzyme very similar to the ADH in the stomach. A coenzyme called nicotinamide adenine dinucleotide (NAD) then converts the components into energy. NAD is the same coenzyme that processes glucose into energy for the body, so while the body is attempting to metabolize alcohol, the body will not convert glucose.

The alcohol that the liver cannot process immediately flows through the blood into the heart, reducing the force with which the heart muscle contracts and lowering blood pressure. It also expands blood vessels, causing warm blood from the center of the body to rise to the surface. As a result, many people get flushed skin after drinking alcohol.

The alcohol also flows into the blood vessels in the lungs, which causes people to exhale alcohol. Alcohol in the bloodstream thereafter flows to the brain, where it slows the transmissions between nerve cells, causing the signs and symptoms of alcohol consumption that we are familiar with.


The liver can process about one half an ounce of pure alcohol every hour. This rate varies from person to person, however. Some people can have alcohol circulating through their bodies for as long as three hours after having one half ounce of pure alcohol.

Gender and Ethnicity Differences in Alcohol Metabolism

A person’s gender can have an effect on how his or her body handles alcohol. Men tend to have more ADH in their stomachs than women do, so more alcohol flows into women’s bloodstreams than men. As a result, women usually begin to feel the effects of alcohol after having consumed less than men. Since women are generally smaller than men, they also have less water in their bodies, allowing alcohol to absorb into the blood more quickly.

A person’s ethnicity also plays a role in how his or her body processes alcohol. Asians, Native Americans and Inuit also produce less ADH in their stomachs, so more alcohol that goes into their bloodstreams.

Interaction with Food

The presence of food can slow the body’s absorption of alcohol. The body needs to process the food in the stomach before it allows liquids into the small intestine. Studies have shown that people who have eaten meals with carbohydrates, fats and protein absorb alcohol more slowly than those with empty stomachs. The absorption rate slows the higher the fat content in the food.

Drunk-driving repercussions vary from state to state, but undoubtedly some of the harshest DUI penalties are from Arizona. If you are facing DUI charges, contacting an experienced criminal defense attorney is recommended.

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