Food essence or nerve poison? Science reveals the health truth behind alcohol!

Food essence or nerve poison? Science reveals the health truth behind alcohol!

When you drink alcohol, how does it move through your body?

As soon as you take the first sip of wine, the body starts to absorb alcohol. Alcohol has a small molecular weight and is both water-soluble and fat-soluble, which allows it to easily cross the cell membrane, quickly enter the adjacent cells from one cell, and diffuse to various parts of the body along the concentration difference.

Alcohol circulates in the human body via the mouth → esophagus → stomach → small intestine → large intestine. Only a very small amount of alcohol in the mouth is absorbed by the mucous membrane, and about 10%-20% of the alcohol that enters the stomach is absorbed. The "main battlefield" for absorption is the intestine - about 80% of the alcohol is absorbed into the blood in the small intestine. At this point, alcohol enters its own "comfort zone" because on the "highway" formed by capillaries, it can quickly travel to various organs throughout the body through blood circulation.

Is it really possible to drink a thousand cups without getting drunk? See how the body metabolizes alcohol

Medical research shows that less than 10% of the alcohol in the body can be directly excreted through urine, breathing, sweat and saliva, and more than 90% of the ethanol must be metabolized in the liver.

The process of alcohol metabolism is: ethanol → acetaldehyde → acetic acid → carbon dioxide and water. Many people believe that the amount of alcohol one can drink is determined by how fast ethanol is metabolized. In fact, the key here lies in acetaldehyde.

Some people tend to blush when drinking alcohol. This is because the activity of acetaldehyde dehydrogenase is low. After ethanol is converted into acetaldehyde, it cannot be decomposed in time, resulting in a large amount of acetaldehyde accumulating in the body. When the concentration reaches a certain level, it will stimulate the expansion of capillaries and cause blushing. So don't believe the rumor that people with blushing faces can drink. If you have a blushing face, you really can't drink.

Some people's faces turn white instead of red after drinking a large glass of wine. Don't be envious. This is because their alcohol dehydrogenase activity is low, and the ethanol they drink accumulates in the body and cannot be converted in time. These people rely on body fluids to dilute alcohol, so they should beware of acute alcohol poisoning caused by excessive ethanol concentration, so they should not drink too much.

In "Demi-Gods and Semi-Devils", Qiao Feng and Duan Yu drink wine and never get drunk. Is there really someone who can drink a lot in real life? - There are indeed people who can drink a lot. Both alcohol dehydrogenase and acetaldehyde dehydrogenase in their bodies are highly active. The conversion process of ethanol → acetaldehyde → acetic acid → carbon dioxide and water is faster. Carbon dioxide is exhaled from the lungs, and water is excreted from the kidneys. Therefore, people who can drink a lot can show a fast metabolic process, sweat easily, and go to the toilet all the time.

Don't try to improve your alcohol tolerance by drinking! Whether it is alcohol dehydrogenase or acetaldehyde dehydrogenase, their activity is basically determined by genes, which means that your alcohol tolerance is basically innate. Some people do improve their alcohol tolerance by drinking, but this actually improves the tolerance to alcohol. Whether it is functional tolerance or metabolic tolerance, it will bring additional burden and risk to the body.

Does alcohol really reduce your IQ and damage your brain?

The blood-brain barrier is one of the tightest barriers in the human body, but due to its strong permeability, alcohol in the blood can cross the blood-brain barrier and reach the brain in just 30 seconds. Alcohol has varying degrees of damage to various parts of the brain, including the key brain area for learning and memory - the hippocampus, the brain area responsible for executive function - the frontal cortex, the higher center for regulating visceral activity - the hypothalamus, and the brain area responsible for coordinating movement - the cerebellum.

Conceptual model of brain regions that differ in cognitive function between alcoholic and non-alcoholic groups, Source: Reference [10]

The British Medical Journal (The BMJ) published a cohort study spanning 30 years, which repeatedly measured the weekly drinking volume of 550 adults and performed magnetic resonance imaging on their brains. The results showed that alcohol intake was related to the risk of hippocampal atrophy. Participants who consumed 30 units of alcohol per week (close to the amount in a bottle of 50-proof liquor) had a 5.8 times higher risk of hippocampal atrophy than non-drinkers.

A highly cited review in Neuropsychology Review showed that alcoholics have reduced frontal lobe neuron density, and that 15-23% of cortical neurons are selectively lost from the frontal association cortex after chronic drinking. In addition, alcoholics also have structural damage to the hypothalamus and cerebellar atrophy.

The brain is the most advanced part of the nervous system. The subsequent effects of long-term alcohol abuse include: memory loss, cognitive dysfunction, decreased control over emotional regulation, executive function and self-regulation disorders, etc. It can be said that there is a scientific basis for the damage of drinking to the brain. Long-term and heavy drinking may cause lasting and irreversible changes to the brain.

Is moderate drinking good for your health?

You may have seen real cases of people living to be 99 by drinking a glass of wine a day. You may have heard that moderate drinking can reduce the risk of cardiovascular disease. In order to find out the health truth behind alcohol, scientists from Peking University, the Chinese Academy of Medical Sciences and the University of Oxford in the UK led a prospective study. They conducted a 10-year questionnaire survey on alcohol use habits and physiological characteristics of diseases among 512,715 adults in 10 regions of China. The results of the study were finally published in The Lancet in April 2019: Alcohol intake evenly increases the risk of high blood pressure and stroke, and has almost no protective effect on the risk of myocardial infarction. Drinking also increases the risk of more than 60 diseases, including cirrhosis, stroke and gastric ulcer.

Is there a safe level of alcohol intake? In March 2018, the Lancet, a top international medical journal, published a study on drinking and disease. Researchers analyzed data sources on drinking in 195 countries and regions around the world from 1990 to 2016. This highly cited authoritative paper shows that there is no so-called healthy drinking amount, or in other words, the safe level of alcohol intake is 0. In addition, don't believe the rumors that drinking can prevent cancer. The World Health Organization reached a firm conclusion many years ago: alcohol is a veritable carcinogen.

Percentage of current drinkers among males aged 15 and above, Source: Reference [12]

According to the 2020 "China's Moderate Drinking and Happy Life Blue Book", there are 450 million drinking consumers in my country, and 123 million people drink excessively. Among the excessive drinking behaviors, 55% are to enhance relationships, 39% are to regulate emotions, and the remaining 26% are to give face to others.

Many people know that drinking is bad, but drinking with friends can help them break down barriers and return to the happy times. Many people do relieve the pressure of life from drinking and feel the joy of "getting some fries from the dock". Therefore, although we know the health truth behind alcohol, we should also look at drinking behavior in combination with reality and establish correct cultural concepts. Whether or not to drink depends basically on genetics and has nothing to do with whether or not to give face. People who drink should not force non-drinkers to drink. Your hobbies may not be the hobbies of others.

References

[1]https://rctff.jiangnan.edu.cn/info/1071/2104.htm

[2]https://www..cn/article/articleinfo?business_type=100&classify=0&ar_id=96372

[3]https://m.thepaper.cn/newsDetail_forward_26583867

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[5]https://new.qq.com/rain/a/20240125A0146F00

[6]https://www.thepaper.cn/newsDetail_forward_19011735

[7]https://www.medsci.cn/article/show_article.do?id=3bfee7770443

[8]https://www.cas.cn/kj/202306/t20230614_4895590.shtml

[9]Topiwala A, Allan CL, Valkanova V, et al. Moderate alcohol consumption as risk factor for adverse brain outcomes and cognitive decline: longitudinal cohort study[J]. bmj, 2017, 357.

[10]Oscar-Berman M, Marinković K. Alcohol: effects on neurobehavioral functions and the brain[J]. Neuropsychology review, 2007, 17: 239-257.

[11]Millwood IY, Walters RG, Mei XW, et al. Conventional and genetic evidence on alcohol and vascular disease aetiology: a prospective study of 500 000 men and women in China[J]. The Lancet, 2019, 393(10183): 1831-1842.

[12]Sheikh A, GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and territories, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016[J]. The Lancet, 2018, 392(10152): 1015.

[13]https://drinkiq.diageo.com.cn/articlefiles/2020_bluebook_cn.pdf

Author: Li Wenjie Popular Science Author

Reviewer: Zhang Yu, researcher/PhD, Chinese Center for Disease Control and Prevention, national health science expert

The article is produced by Science Popularization China-Creation Cultivation Program. Please indicate the source when reprinting.