Table of Contents
Alcoholic beverages have accompanied humanity for centuries. No matter where you look in history, you’ll find records of wine, beer, or other fermented drinks that, in larger quantities, altered consciousness. Alcohol was even believed to have healing properties, despite the fact that excessive drinking often led to hangovers, headaches, and dehydration. It was not only consumed to accompany meals—since water was often contaminated—but also as a key part of celebrations. Today, alcohol remains a central feature of social events. It’s become so normalised that those who abstain are often considered odd. Yet the truth remains that alcohol, by many measures, is one of the most harmful substances. It damages not only the physical and mental health of the drinker but also affects those around them.
Alcohol Is a Drug
Despite being widely available in shops, alcohol is still classified as a drug. The key ingredient responsible for its effects is ethanol. The problem with ethanol lies in how it works. Most other drugs either mimic substances found in the brain (like opiates) or act on specific receptors in the brain (such as THC). Ethanol, however, is a small molecule that can pass through cell membranes, influencing the functioning of cells from the inside.
The exact mechanism of ethanol’s action isn’t entirely clear. Due to its small size, ethanol spreads throughout the body by diffusion, easily reaching various parts of the body. It was once believed that its effects on the central nervous system (CNS) were non-specific. Today, we know of over 20 potential sites of action in the brain, including its effects on GABA receptors, the serotonin and dopamine systems, and even opioid receptors.
More than 90% of consumed ethanol is metabolised, while the rest is excreted through urine, sweat, and breath. After drinking, ethanol enters the bloodstream from the digestive tract and is transported to the liver. Even one drink (0.04 litres of spirits, a beer, or a glass of wine) can place a strain on the liver and its ability to metabolise ethanol. As a result, ethanol remains in the body for an extended period, affecting not just the brain but all other organs as well.
In the liver, ethanol is broken down by the enzyme alcohol dehydrogenase into acetaldehyde. Acetaldehyde is toxic and carcinogenic, so it’s quickly converted by another enzyme, acetaldehyde dehydrogenase, into acetate (the ion form of acetic acid), which is only mildly toxic and can be used as an alternative energy source. It’s thought that acetate is one of the primary causes of hangovers.[1]
Alcohol’s effect on the dopamine system is largely responsible for its highly addictive nature and the development of dependency. The more alcohol a person consumes, the more dopamine is released, leading to an increased likelihood of addiction.[2]
The acute effects of alcohol depend on the percentage of alcohol in the bloodstream. However, the commonly used measurement is ‰ (per mille). The effects can generally be categorised as follows:
Effect | |
|---|---|
| 0.2 – 0.39 | Normal coordination, with slightly reduced inhibitions. |
| 0.4 – 0.59 | A sense of well-being, mild euphoria, feeling warm, slightly impaired judgment, and reduced attention. |
| 0.6 – 0.99 | Slightly impaired balance, speech, vision, reaction time, and hearing. Euphoria combined with reduced self-control. Memory impairment. |
| 1 – 1.29 | Significant impairment of balance, noticeable loss of attention, slurred speech, reduced peripheral vision, and slower reaction time. |
| 1.3 – 1.59 | Severely impaired coordination and motor control. Blurred vision and loss of balance. Euphoria gives way to dysphoria (unpleasant feelings). |
| 1.6 – 1.99 | Dysphoria and nausea. The typical picture of a highly intoxicated, uncoordinated person. |
| 2 – 2.49 | Need for assistance when walking. Complete mental confusion. Dysphoria with nausea and vomiting, with the possibility of losing consciousness. |
| 2.5 – 3.99 | Alcohol poisoning. Loss of consciousness. |
| 4 and more | Coma and potential death due to respiratory failure. |
[3]
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Effects of Alcohol on the Brain
Alcohol reaches the brain through the bloodstream, just like the rest of the body. Since it doesn’t require digestion, it travels directly from the digestive system into the blood. As mentioned earlier, while its effects on the brain are widely studied, there isn’t a single mechanism that fully explains how it works. One of the most well-known mechanisms is its influence on GABAA receptors, similarly to how some anaesthetics function. It slows down the CNS and acts as a depressant, which is why we feel more relaxed and confident after drinking.[4]
In addition to GABAA receptors, which are linked to ion channels, ethanol also affects other ion channels. In some cases, it has a suppressive effect, while in others, it excites the brain’s signal transmissions, contributing to an overall imbalance and dysfunction of the CNS.
Like any drug, ethanol damages the brain. Among both legal and illegal substances, ethanol is one of the most harmful in terms of brain cell degeneration. It also slows down neurogenesis and neuroplasticity – the formation of new connections between brain cells.[5] Additionally, ethanol can trigger programmed cell death (apoptosis).[6]
A 2022 study involving over 39,000 participants showed that even the equivalent of one small beer a day leads to significant brain shrinkage and accelerated brain ageing. Naturally, this effect worsened with an increased number of drinks per day. Based on this and other studies, it’s been clearly proven that there is no safe amount of alcohol.[7]
The chronic effects of alcohol consumption severely impair brain function, contribute to brain mass loss, and, in severe cases of alcoholism, can lead to alcohol-induced dementia.
How Does Alcohol Affect the Body Beyond the Brain?
In addition to its harmful effects on the brain, alcohol consumption is a significant risk factor for many diseases. Pinpointing its exact mechanisms is challenging because alcohol spreads throughout the entire body without much restriction.
Cardiovascular System
Even minimal alcohol intake increases the risk of cardiovascular diseases. Studies that once suggested a protective effect of moderate alcohol consumption on heart health have been found to be misleading. Recent data now indicate that alcohol raises the risk of cardiovascular issues, regardless of the amount consumed.[8] One of the primary reasons for this heightened risk is alcohol’s impact on blood pressure. Regular alcohol consumption leads to consistently elevated blood pressure, which increases the likelihood of heart failure. The risk of stroke is also heightened.[9]
Long-term alcohol use also leads to alcohol-induced toxicity, which causes cardiomyopathy (a group of heart muscle diseases). This results in irreversible damage to the heart and its functions, leading to heart failure and arrhythmias. If someone with this condition continues to drink, their risk of death in the next 10 years rises to 80%.[10]
Digestive System
The digestive system also suffers from alcohol consumption, with liver damage being the most well-known issue. The liver works hard to metabolise alcohol into less harmful substances, but it has a limited capacity, which can be quickly overwhelmed. Frequent overloading of the liver leads to damage and eventually cirrhosis. Cirrhosis occurs when the liver forms scar tissue as a response to irreversible damage, which hampers its normal function. Cirrhosis ranks among the top 10 causes of death worldwide.
In addition to cirrhosis, alcoholic hepatitis (inflammation of the liver) and fatty liver disease (where fat accumulates in the liver and can lead to inflammation and cirrhosis) are common. Pancreatitis (inflammation of the pancreas) and an increased risk of pancreatic cancer are also frequent outcomes of heavy alcohol use.[11]
Cancer
Alcohol consumption is linked to a higher risk of various cancers because ethanol is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), placing it in the same category as substances found in cigarette smoke. Ethanol’s carcinogenic effect is due to its easy passage through cell membranes, where it causes DNA methylation, disrupting gene regulation. It also induces oxidative stress, further damaging DNA. This often leads to breast cancer, colorectal cancer, oral cancer, and liver cancer.[12]
Additional Negative Health Effects
- Alcohol consumption also impacts the immune system by disrupting signalling pathways and triggering the release of pro-inflammatory substances, partly due to its effect on the gut microbiome.[13]
- A common condition associated with alcohol use is alcoholic neuropathy, which involves nerve damage directly caused by ethanol. This manifests as poor coordination (even when sober), paresthesia (numbness and tingling in the extremities), and pain.[14]
- Alcohol consumption negatively affects sleep quality. While high blood alcohol concentration can have a sedative effect and speed up the process of falling asleep, the overall quality of sleep is significantly impaired, which adversely impacts both physical and mental health.[15]
- Chronic alcohol consumption reduces testosterone production in men after just eight drinks per week. Lower testosterone levels affect not only fertility but also libido and overall physical performance, both in and out of the bedroom.[16]
- Moreover, both acute and chronic alcohol use take a toll on mental health. Although the temporary effects can provide relief, alcohol actually exacerbates symptoms of anxiety and depression. High doses lead to immediate negative effects, while milder consumption often results in anxiety and depressive symptoms after sobriety. As a dependency on alcohol develops, individuals can find themselves trapped in a vicious cycle that is difficult to escape, impacting not only their lives but also the lives of those around them. In terms of its negative impact on mental health and social surroundings, alcohol is arguably the worst drug known to humanity.[17]
Even moderate alcohol consumption, which is often considered harmless, affects health on multiple levels. It can easily escalate into chronic use associated with addiction, leading to rapid physical decline. Organ damage, such as to the heart or brain, from excessive alcohol intake is often irreversible and permanently affects those who succumb to this addiction.
Alcohol as a Risk Factor for Obesity
Alcohol consumption is often overlooked when counting calories. This is a mistake, as ethanol itself has caloric value. In comparison to common macronutrients, fats provide about 9 kcal/g, while carbohydrates and proteins each provide around 4 kcal/g. Ethanol in alcoholic beverages contains approximately 7 kcal/g. Thus, an evening spent enjoying wine can equate to consuming as many calories as a small dinner. Additionally, if food is consumed during this time, it turns the wine-drinking occasion into a nutritionally poor calorie bomb.
The calories found in alcoholic beverages can be particularly dangerous. They not only increase your caloric intake, potentially leading to weight gain, but they also represent what are known as “empty calories,” lacking any nutritional value. For example, consuming just one can of beer a day can add nearly 1,500 kcal to your weekly intake without providing any benefits for your body.
Conclusion
Alcohol consumption is so normalized worldwide that we actively ignore its negative impacts on health. However, alcohol rightfully belongs to the category of narcotic and addictive substances. Unlike most drugs, it can disrupt the functioning of the entire body and damage all the organs it reaches. Due to its size, the ethanol molecule can penetrate everywhere. By increasing oxidative stress, damaging DNA, and disrupting the overall homeostasis of the body, alcohol causes harm throughout the entire system. Therefore, the healthiest amount of alcohol is none at all.
[1] Maxwell, C. R., Spangenberg, R. J., Hoek, J. B., Silberstein, S. D., & Oshinsky, M. L. Acetate Causes Alcohol Hangover Headache in Rats – https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0015963
[2] Ma H, Zhu G. The dopamine system and alcohol dependence – https://pubmed.ncbi.nlm.nih.gov/25092951/
[3] Blood alcohol concentration - University of Notre Dame. (n.d.). – https://mcwell.nd.edu/your-well-being/physical-well-being/alcohol/blood-alcohol-concentration/
[4] Ingrid A. Lobo; R. Adron Harris. (2008). GABAA receptors and alcohol – https://pubmed.ncbi.nlm.nih.gov/18423561/
[5] Crews F. T. (2008). Alcohol-related neurodegeneration and recovery: mechanisms from animal models – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3860462/
[6] Han, Jae Yoon et al. “Ethanol induces cell death by activating caspase-3 in the rat cerebral cortex.” – https://www.sciencedirect.com/science/article/pii/S101684782313216X?via%3Dihub
[7] Daviet, R., Aydogan, G., Jagannathan, K. et al. Associations between alcohol consumption and gray and white matter volumes in the UK Biobank – https://www.nature.com/articles/s41467-022-28735-5
[8] Schutte, Rudolph et al. “Alcohol - The myth of cardiovascular protection.” - – https://pubmed.ncbi.nlm.nih.gov/34999329/
[9] Tackling G, Borhade MB. Hypertensive Heart Disease (2024) – https://www.ncbi.nlm.nih.gov/books/NBK539800/
[10] Shaaban A, Gangwani MK, Pendela VS, et al. Alcoholic Cardiomyopathy – https://www.ncbi.nlm.nih.gov/books/NBK513322/
[11] Varghese J, Dakhode S. Effects of Alcohol Consumption on Various Systems of the Human Body: A Systematic Review – https://pubmed.ncbi.nlm.nih.gov/36381944/
[12] Rumgay H, Murphy N, Ferrari P, Soerjomataram I. Alcohol and Cancer: Epidemiology and Biological Mechanisms – https://www.mdpi.com/2072-6643/13/9/3173
[13] The gastrointestinal microbiome: alcohol effects on the composition of intestinal microbiota. Engen PA, Green SJ, Voigt RM, Forsyth CB, Keshavarzian A. – https://pubmed.ncbi.nlm.nih.gov/26695747/
[14] Sadowski A, Houck RC. Alcoholic Neuropathy: – https://www.ncbi.nlm.nih.gov/books/NBK499856/
[15] Colrain IM, Nicholas CL, Baker FC. Alcohol and the sleeping brain – https://pubmed.ncbi.nlm.nih.gov/25307588/
[16] Koh K, Kim SS, Kim JS, Jung JG, Yoon SJ, Suh WY, Kim HG, Kim N. Relationship between Alcohol Consumption and Testosterone Deficiency according to Facial Flushes among Middle-Aged and Older Korean Men – https://pubmed.ncbi.nlm.nih.gov/36444123/
[17] Drug harms in the UK: a multicriteria decision analysis Nutt, David J et al. The Lancet - – https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)61462-6/fulltext
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