Alcohol metabolism may be the key to drinking risk

Heavy drinking can increase the risk of negative health consequences ranging from liver disease to cancer. But some alcoholics seem to be more prone to these problems than others.

Researchers believe that the difference between people at higher risk and those at lower risk may involve how the body metabolizes, breaks down, and eliminates alcohol, which may vary from person to person.

How fast is the metabolism of alcohol?

No matter how much alcohol you drink, your body can only metabolize a certain amount of alcohol per hour. According to data from the National Institute of Alcohol Abuse and Alcoholism, fasting adult men may take 2 to 7 hours to return to zero blood alcohol content (BAC) or blood alcohol concentration after consuming 1 to 4 glasses of standard alcohol quickly level.

People who only drank one beverage recorded a BAC of 0.00 after more than two hours. Those who drank four glasses in the first hour did not return to a blood alcohol concentration (BAC) of 0.00 until seven hours later.

The results show that the body can only break down and eliminate so much alcohol per hour. It is important to remember that these times are averages.

In fact, the time it takes for each person to metabolize alcohol varies greatly. But in all cases, the metabolism of alcohol is slower than absorption.

How the body metabolizes alcohol

When drinking alcohol, it is absorbed into the blood from the stomach and intestines. Then enzymes, which break down other chemical substances in the body chemicals, begin to metabolize alcohol.

Two liver enzymes, Alcohol Dehydrogenase (ADH) and Aldehyde Dehydrogenase (ALDH), begin to break down alcohol molecules and eventually excrete them from the body. ADH helps convert alcohol into acetaldehyde. Acetaldehyde only exists in the body for a short time because it is quickly converted into acetate by other enzymes.

Although acetaldehyde exists in the body for a short time, it is highly toxic and a known carcinogen.

As mentioned above, most alcohol is metabolized by the liver, but a small amount of alcohol is excreted through the formation of fatty acid ethyl esters (FAEE), which have been found to damage the liver and pancreas. Finally, a small amount of alcohol is not metabolized, but is excreted through breathing and urine. This is how BAC is measured in breath and urine tests.

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The hazards of acetaldehyde

Acetaldehyde can cause severe damage to the liver, because most alcohol is broken down into toxic by-products in the liver. In other words, some alcohol is metabolized in the pancreas and brain, and acetaldehyde can also damage cells and tissues.

A small amount of alcohol is metabolized in the gastrointestinal tract, and acetaldehyde can also damage the gastrointestinal tract. Some researchers believe that the effects of acetaldehyde exceed the damage it causes to tissues, but it may also be the cause of some behavioral and physiological effects caused by alcohol.

Acetaldehyde and damage

When researchers administered acetaldehyde to laboratory animals, it caused uncoordinated movements, memory impairment, and drowsiness. Other researchers claim that acetaldehyde alone cannot cause these effects because the brain protects itself from toxic chemicals in the blood through its unique blood-brain barrier.

However, when catalase and CYP2E1 metabolize alcohol—this happens only when ingested in large quantities—the brain itself produces acetaldehyde.

Genetics and metabolism

The size and weight of the liver of a drinker are factors that determine how much alcohol a person can metabolize in an hour, but research tells us that a person’s genetic makeup may be the most important factor in the decomposition and decomposition efficiency of alcohol. eliminate.

Variations in the ADH and ALDH enzymes can be traced back to variations in the genes that produce these enzymes. Some people’s ADH and ALDH enzymes work less efficiently than others, while others’ enzymes are more effective. In short, this means that some people’s enzymes can break down alcohol into acetaldehyde or acetaldehyde into acetate faster than others.

If someone has fast-acting ADH enzyme or slow-acting ALDH enzyme, they will accumulate toxic acetaldehyde in their body, which can have dangerous or unpleasant effects when they drink alcohol.

The difference between men and women

Women absorb and metabolize alcohol differently from men. Studies have shown that the ADH enzyme activity in the stomach of women may be low, allowing a greater proportion of alcohol to enter the bloodstream before being metabolized.

This may be one of the reasons why women who drink alcohol are more likely to suffer from alcoholic liver disease, myocardial damage and brain damage than men.

Genetics and alcoholism

Genetics may also be a factor in whether a person is susceptible to alcohol use disorder.

For example, a variation of these enzymes can cause acetaldehyde to accumulate, leading to facial flushing, nausea, and increased heart rate. Even moderate drinking can have these effects.

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This genetic mutation is common among Chinese, Japanese, and Koreans, who may drink less alcohol due to unpleasant side effects. Their genetic mutations have a protective effect on the development of alcoholism. This protective gene ADH1B*2 is rarely found in people of European and African descent. Another variant, ADH1B*3, is found in 15% to 25% of African Americans and prevents alcoholism.

In other words, a study found that the variation of ALDH enzyme, ALDH1A1*2, and ALDH1A1*3 may be related to African American alcoholism.

Not all genetic

According to the National Library of Medicine (NLM), there is no clear genetic pattern for alcohol use disorder, but the children of people with alcohol use disorder are still 2 to 6 times more likely to have alcohol problems than the general population for self-use. Part of this increased risk may be due to some common genetic factors, but experts also believe that common environmental and social factors may also be at work.

For example, although studies have found that Japanese alcohol addicts carrying the protective ADH1B*2 gene version increased from 2.5% to 13% between 1979 and 1992, alcohol consumption in Japan also increased significantly.

In the United States, more Native Americans die from alcohol-related causes than any other race, but researchers have found that there is no difference in enzyme patterns or alcohol metabolism rates between Native Americans and Caucasians, indicating that there are other factors at play. Role in the development of alcohol-related issues.

Health consequences

Heavy or long-term drinking is associated with a series of negative health consequences and long-term adverse effects. Some of these health problems are directly related to the way alcohol is metabolized in the body and the production of acetaldehyde.


The toxic effects of acetaldehyde are related to the occurrence of oral cancer, laryngeal cancer, upper respiratory tract cancer, liver cancer, colon cancer and breast cancer. Ironically, genes that “protect” certain people from alcoholism may actually increase their risk of cancer.

Although they are unlikely to drink a lot of alcohol, these people are at greater risk of cancer because their bodies produce more acetaldehyde when they drink alcohol. Therefore, even some people who drink moderately have a greater risk of cancer.

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Alcohol-related liver disease

Because the liver is the organ that metabolizes most of the alcohol in the body, it is the place where most of the acetaldehyde is produced, and it is particularly susceptible to the effects of alcohol metabolism. More than 90% of heavy drinkers will develop fatty liver.

Alcohol-related pancreatitis

Since some alcohol metabolism is also carried out in the pancreas, it is exposed to high levels of acetaldehyde and FAEE. However, less than 10% of heavy drinkers will develop alcoholic pancreatitis, which suggests that drinking is not the only cause of this disease.

Other factors may include differences in smoking, diet, drinking patterns, and alcohol metabolism patterns that may play a role, but none of them are clearly linked to pancreatitis.

Weight gain

Drinking alcohol does not necessarily lead to weight gain, although its caloric value is relatively high. Although moderate drinking does not cause weight gain in thin men or women, studies have found that adding alcohol to the diet of overweight people does cause weight gain.

Effects on sex hormones

In men, alcohol metabolism can cause testicular damage and impair testosterone synthesis and sperm production. Long-term lack of testosterone may lead to feminization of men, such as breast enlargement.

In women, alcohol metabolism may lead to increased estradiol production and decreased estradiol metabolism, leading to elevated levels. Estradiol helps increase bone density and reduce the risk of coronary artery disease.

Interaction with drugs

Drinking alcohol can affect the metabolism of many different drugs, increasing the activity of some drugs and reducing the effectiveness of others.

It has been found that long-term heavy drinking can activate the CYP2E1 enzyme, which converts paracetamol into a toxic chemical, which can cause liver damage even when taken in conventional therapeutic doses.

Metabolism-based treatment

Research funded by the National Institute of Alcohol Abuse and Alcoholism continues to study how changes in the way the body metabolizes alcohol affects why some people drink more alcohol than others, and why some people have serious alcohol-related health problems.

Researchers believe that how the body breaks down and eliminates alcohol may be the key to explaining these differences, and ongoing research may help develop metabolism-based treatments for drinkers who are at risk of alcohol-related health problems.


Alcohol metabolism may be the key to drinking risk
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