‘In Vino Veritas’ or ‘in wine lies truth’ are well-known words supposedly uttered 2600 years ago by the poet Alcaeus of Mytilene. Since ancient civilizations, humans have been familiar with alcoholic beverages; its effects are documented as far back as biblical texts. Depending on the amount consumed, alcohol can cause blackouts, headaches, nausea or fatigue. But what actually happens to the glass (or glasses) of wine we consume after it enters the human body?
What is Alcohol?
This might come along as a stupid question at first, but have you ever thought about what goes in an alcoholic drink? In daily life, the term is mostly used to describe alcohol we find in drinks: ethanol (or ethyl alcohol).
Ethanol consists of 2 carbon atoms, 5 hydrogen atoms and 1 hydroxyl group, or C2H5OH in chemical notation. It derives its name from the ethane structure (C2H5) fused with the alcohol group (-OH). It is widely used in laboratories as a solvent or disinfectant, and also in our everyday lives as a beverage2.
But there are many other kinds of alcohols as well; in the chemical sense, alcohols are defined as hydrocarbons containing one or more hydroxyl (-OH) groups bonded to a saturated carbon.
A well-known example is methanol, just a methyl group (CH2) short of ethanol. But methanol exhibits different toxicity compared to ethanol and a small amount can be very harmful, even deadly.
Another alcohol some might not recognize as such is glycerin (aka glycerol). Glycerin is used in different ways such as in the cosmetics industry (just look on your shower gel bottles or moisturizers), fuels, dyes, pesticides and even in the production of nitroglycerin1!
Ethanol in our Body
The first documented alcoholic beverage was produced 9000 years ago in China, a wine-like drink made from fermenting rice, honey and fruit. Nowadays count varieties of crops and other ingredients are fermented through biological processes (beer, wine, cider) or distilled (vodka, whiskey, rum) to create an ethanol-containing drink17.
Ethanol to Acetaldehyde to Acetate
It turns out that the ethanol molecule itself is mostly harmless to the body. Unfortunately, this doesn’t mean your body doesn’t react to it. As soon as ethanol reaches the liver, it is metabolized (chemically changed) by enzymes into acetaldehyde. This process also generates free radicals that are highly reactive.
It is acetaldehyde that causes cell and tissue damage, inhibition of cell repair functions, blocking of protein synthesis and can even trigger an immune response3. Another effect of acetaldehyde is that they cause the swelling of liver cells (hepatocytes), thought to be a factor in the development of alcohol-induced liver diseases like cirrhosis7.
Acetaldehyde is then further metabolized by the enzyme ALDH to an acetate salt that dissolves well in water. Acetate leaves the liver through the bloodstream where it can affect blood pH, the nervous system and other metabolic pathways before being excreted.
Reducing Oxygen
So our body has enzymes that deal with alcohol, great! But as can be seen from the diagram, oxygen is required for the metabolism of ethanol. the very same oxygen that is also required for us to survive. Furthermore, the production of carbon dioxide increases its concentration in the blood 3. Have you ever noticed that your heartbeat increases after drinking? That is, in fact, one of the effects of hypoxia—oxygen deficiency in your cells4.
Diuretic Properties
Another effect observed after consuming alcohol is the urge to use the toilet, due to its action as a diuretic (just like caffeine). The kidney produces vasopressin, an antidiuretic hormone, which allows water to pass through the membranes of kidney cells and transport it back into the body. Ethanol is able to inhibit the production of this hormone, preventing the reuptake of water and causes dehydration, leading to many of the symptoms associated with a ‘hangover’5. Apart from dehydration, electrolyte concentrations in the blood like sodium, potassium, phosphate, magnesium and calcium can also be disrupted, causing complications6.
Liver Damage
The liver–contributing to 90% of ethanol metabolism–is also at risk of overuse. Metabolic products such as acetaldehyde and free radicals damage the liver cells and can trigger a local inflammation caused by cytokines (i.e. interleukins) from our own immune system. If triggered regularly, the individual is at higher risk for diseases like fatty liver, cirrhosis and even liver cancer7.
Alcohol as a Teratogen
Apart from affecting the individual consuming it, ethanol also has teratogenic properties, causing damage to an unborn child. A child’s brain is at high risk of oxidative damage caused by products of alcohol metabolism as the undeveloped organ has low levels of antioxidants. Additional reactions such as the breaking down of membrane components by alcohol-mediated enzymes can cause damage resulting in defects and decreased size of the fetal brain3.
Alcohol and the Brain
Loss of Brain Function
A common symptom of alcohol consumption is a headache, ranging from mild to severe. This is linked to a low amount of free magnesium and calcium ions in the brain which impacts enzymes, neurotransmitters and other functions8,9. Alcohol also serves as a trigger for migraine attacks in patients susceptible to them10. But does alcohol actually damage the brain irreversibly?
According to a study looking at various IQ and memory scores meant to quantify brain function, individuals who consumed alcohol more than 3 times a week scored lower on the test (90-100) compared to the control group (around 110)11.
Furthermore, a loss of brain mass can be observed in alcoholics, especially in the amount of ‘white matter’ that connects regions of the brain with each other. Studies on rats have shown that excessive intake of alcohol causes a reduction in nerve fibers and myelin (the insulative substance surrounding white matter); this is associated with neurological disorders and cognitive decline12.
Does Alcohol Really Kill Brain Cells?
The matter of whether the brain is able to repair these regions after an extended period of alcohol abstinence is still uncertain. So while alcohol use may not ‘kill’ brain cells, it surely does have a long-term negative impact on how well your brain works!
A more acute problem that may occur right after an individual consumes a large amount of alcohol is a ‘blackout’. Due to the severity of intoxication, the brain is unable to cope with the chemical imbalance and its storage processes are temporarily halted. This means that it can’t save the memories created around this time; sort of like forgetting to save a file before the computer crashes13.
Alcohol and Mental Health
Another potentially dangerous effect of alcohol consumption is its impact on cognitive control. After one or two drinks people tend to get more talkative, honest and daring.
Alcohol affects inhibitory control which lowers behavioral thresholds that can result in an individual carrying out unusual actions and feeling good in the process. This loss of control leads to craving even more alcohol, explaining why some people binge drink to the point of severe intoxication.
This inhibition seems to be linked with aggressive behavior; alcoholics are up to two times more likely to engage in violent behavior than moderate drinkers14. Scientists have found that alcohol stimulates serotonin and dopamine release, which is associated with ‘social stress‘.
Alcohol also impairs the function of our prefrontal cortex and amygdala, parts of the brain responsible for emotional responses. This is the reason why alcohol consumption often leads to aggressive and violent behavior15.
What’s The ‘Healthy’ Amount?
Of course, some of us just like a drink or two when we’re chilling with friends or at social events, and others go so far as to claim that moderate alcohol consumption is actually beneficial to health.
However, this claim is yet to be substantiated. And it might be a long shot seeing as alcohol consumption is strongly linked with type 2 diabetes, heart disease, stroke, liver disease, brain damage and mental illness16.
In today’s society, there is constant social pressure to ‘just have a drink’. Many people simply accept a drink in order to avoid coming across as boring or antisocial, although they don’t actually want to. Many social environments revolve around drinking, with questions being asked if there isn’t alcohol around, to the point where people even get called out for not drinking.
Everyone should be able to decide whether or not to drink, free of pressure; it is important to raise awareness of the dangers of alcohol use and misuse so that people are aware of the risks involved. More importantly, with this knowledge in hand, everyone can contribute by not pressuring others when they refuse ‘just one more drink’.
NOTE
If you or somebody you care about is affected by alcohol abuse, there is help available to get you through it. Nobody should feel ashamed or alone. If you feel like this could be an issue in your life, here are just several of many organizations that you can reach out to:
drugabuse.com
alcoholics-anonymous.eu
drinkaware.co.uk
drinkwise.org.au
Reference
- National Center for Biotechnology Information. PubChem Compound Database; CID=753. PubChem (accessed Sept. 16, 2018).
- National Center for Biotechnology Information. PubChem Compound Database; CID=702. PubChem (accessed Sept. 16, 2018).
- Samir Zakhari. (2006). Overview: How is alcohol metabolized by the body?. Alcohol research & health : the journal of the National Institute on Alcohol Abuse and Alcoholism. 29. 245-54.
- R. P. Cafaro (1960). Hypoxia: Its Causes and Symptoms. Journal of the American Dental Society of Anesthesiology, 7(4), 4-8.
- Murray Epstein. (1997). Alcohol’s Impact on Kidney Function. Alcohol Health & Research World. Vol. 21, No. 1, 1997. 84-93.
- Charles R. Kleeman, Milton E. Rubini, Ezra Lamdin, Franklin H. Epstein. (1954). Studies on Alcohol Diuresis. II. The Evaluatoin of Ethyl Alcohol as an Inhibitor of the Neurohypophysis. Department of Internal Medicine, Yale University School of Medicine. 448-454.
- Suzanne Sargent, Kerry Webb. (2009). Liver Diseases: An Essential Guide for Nurses and Health Care Professionals. 93-96
- Burton M. Altura, Bella T. Altura. (1998). Association of Alcohol in Brain Injury, Headaches, and Stroke with Brain?Tissue and Serum Levels of Ionized Magnesium: A Review of Recent Findings and Mechanisms of Action. Alcohol. Volume 19, Issue 2. 119-130.
- Robert Swift, Dena Davidson. (1998). Alcohol Hangover Mechanisms and Mediators. Research World. Vol. 22, No. 1, 1998. 54-60
- Alessandro Panconesi. (2016). Alcohol-induced headaches: Evidence for a central mechanism? Journal of Neurosciences in Rural Practice, 7(2), 269-275.
- Maureen P. Molloy. (1984). Alcohol related brain damage. Drug and Alcohol Review. Volume 3, Issue 2, July 1984. 104-106.
- Clive Harper. (2009). The Neuropathology of Alcohol-Related Brain Damage. Alcohol and Alcoholism. Volume 44, Issue 2, 1 March 2009. Pages 136-140.
- Hamin Lee, Sungwon Roh, Dai Jin Kim. (2009). Alcohol-Induced Blackout. International Journal of Environmental Research and Public Health. 6(11), 2783-2792.
- Matt Field, Reinout W. Wiers, Paul Christiansen, Mark T. Fillmore, Joris C. Verster. (2010). Acute Alcohol Effects on Inhibitory Control and Implicit Cognition: Implications for Loss of Control over Drinking. Alcoholism: Clinical and Experimental Research. Vol. 34, No.8, August 2010. 1346-1352.
- Adrienne J. Heinz, Anne Beck, Andreas Meyer-Lindenberg, Philipp Sterzer, Andreas Heinz. (2011). Cognitive and neurobiological mechanisms of alcohol-related aggression. Nature Reviews Neuroscience. Vol. 12, Juli 2011. 400-413.
- Tanya Chikritzhs, Tim Stockwell, Timothy Naimi, Sven Andreasson, Frida Dangardt, Wenbin Liang, (2015). Has the leaning tower of presumed health benefits from ‘moderate’ alcohol use finally collapsed?. Addiction, 110. 726-727.
- Andrew Curry. (2017). Our 9,000-Year Love Affair with Booze. National Geographic Magazine. February 2017.
About the Author
Katharina was a science writer at FTLOScience from July 2018 to October 2019.
