February 17, 2021

Decomposition of Alcohol and Acetaldehyde

 

Although we use the term alcohol to refer to alcoholic beverages, beverages that contain ethyl alcohol are generally referred to as “alcoholic beverages. The chemical formula for ethyl alcohol is C2H5OH.

This ethyl alcohol is broken down in the body, especially in the liver, and the result of this process is acetaldehyde (CH3CHO).

Acetaldehyde is an indispensable substance for industries such as acetic acid production and solvents for paints, but on the other hand, if the concentration of acetaldehyde in the body increases, it can cause hangovers, lower liver function, and cause inflammation.

First, ethyl alcohol enters the body and becomes toxic acetaldehyde in the liver, and then acetate (CH3COOH), which is harmless to the body. The acetate is then passed from the liver to the bloodstream where it is further broken down into carbon dioxide and water.

Here is an explanation of how ethyl alcohol enters the body, becomes acetaldehyde, and is then broken down.

Decomposition of acetaldehyde

When you drink alcohol, 20% of the ethyl alcohol is absorbed in the stomach and 80% in the small intestine, and the absorbed ethyl alcohol flows into the bloodstream. At this time, the absorption speed is fast, ranging from 30 minutes to 2 hours. At this stage, it is still ethyl alcohol.

 

 

This ethyl alcohol then passes through the liver as it travels through the bloodstream throughout the body.

Once in the liver, ethyl alcohol is oxidized by the enzyme “alcohol dehydrogenase (ADH)” to acetaldehyde. This is referred to as primary metabolism.

Alcohol dehydrogenase (ADH), also known as alcohol dehydrogenase, is found in small amounts in the stomach, intestines, kidneys, retina, and brain, but the majority is found in the liver. Therefore, acetaldehyde is almost always made in the liver.

After the primary metabolism, the secondary metabolism takes place.

Acetaldehyde, which is toxic in the body, is converted to acetic acid, which is harmless. The enzyme used in this process is called acetaldehyde dehydrogenase (ALDH).

There are two types of acetaldehyde dehydrogenase (ALDH), ALDH1 (type 1) and ALDH2 (type 2). ALDH2 (type 2) is mainly responsible for the oxidation of acetaldehyde to acetic acid, but ALDH1 (type 1) is also involved in this process.

However, people who are generally said to be weak in alcohol are said to have weak activity of ALDH2 (type 2). The reason why Japanese people are said to be weak in alcohol is because of this ALDH2 (type 2).

 

 

In the liver, ethyl alcohol becomes acetaldehyde, which is harmless to the body, and then acetyl CoA, which is used as energy in the “TCA cycle” (TCA circuit, citric acid circuit) to become carbon dioxide and water. After that, it is discharged from the body as urine.

I will explain more about the TCA cycle in the future, but alcohol and acetaldehyde decomposition means that ethyl alcohol becomes toxic acetaldehyde, which becomes harmless acetic acid, which becomes carbon dioxide and water.

If this decomposition does not go well and acetaldehyde remains in the body, it can cause a bad hangover, or if it remains undecomposed until the next day, it can cause a hangover.

Alcohol is broken down almost entirely by the “mitochondria” in the liver, and in order for these mitochondria to break down alcohol smoothly, it is important to have a large amount of oxygen, sugar, and the energy produced by breaking down the alcohol.

 

 

 

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