This blog post examines the various physiological causes of hangovers and introduces effective methods to alleviate them accordingly.
Introduction
As many office workers can relate, December is a time when appointments become particularly frequent. A significant number of these appointments often conclude with drinking sessions or begin as drinking engagements from the start. As drinking days become more frequent, everyone experiences a hangover at least once. I, in particular, have a low tolerance for alcohol. When I try to keep up with my seniors or peers during drinking sessions, I often find myself vomiting or clutching my head in agony from a headache. Looking up ‘hangover’ in the dictionary, it’s defined as ‘an intoxication that lingers into the next day’. Specific hangover symptoms include vomiting, headaches, loss of appetite, sensitivity to light and sound, rapid heartbeat, tremors, and sweating. So why does this hangover occur? If we understand the cause, might there be a way to resolve this persistent misery? My personal curiosity about these questions motivated this blog post. This article will explain how acetaldehyde, the most widely recognized cause of hangovers, induces hangover symptoms within the body. It will also introduce various theories on hangover causes, including the inflammatory response hypothesis, the direct effects of alcohol, the isomer hypothesis, and the lactic acid hypothesis. Furthermore, it will explore whether controlling these causes can resolve hangovers and discuss potential methods.
What causes a hangover?
Hangovers occur due to the combined effects of multiple causes. Among these, acetaldehyde is particularly well-known. Acetaldehyde is a metabolic byproduct formed when ethanol is broken down by alcohol dehydrogenase in the liver. This substance stimulates the vagus nerve, affecting motor function, perception, and visceral functions, thereby causing hangovers. It is also known to stimulate the afferent nerve fibers of the sympathetic nervous system, which activates in response to external stress, triggering hangover symptoms. Acetaldehyde forms covalent bonds with various proteins in the liver, altering its function and structure. For example, it binds to tubulin, which forms microtubules within hepatocytes, reducing microtubule polymerization and disrupting protein secretion. Furthermore, acetaldehyde swells hepatocytes and forms adducts that inhibit enzyme activity. These adducts promote the production of antibodies against the acetaldehyde epitope, triggering an immune response that exacerbates or perpetuates alcohol-induced liver damage.
Given that hangover symptoms resemble those of bacterial invasion, a hypothesis exists that hangovers represent a type of inflammatory response. One study suggests that excessive drinking promotes the production of ethanol-induced cytokines, signaling molecules that activate the immune system. Cytokines are substances that trigger inflammatory responses. Specifically, elevated levels of cytokines like interleukin-10, interleukin-12, and interferon-gamma can cause flu-like symptoms. Research also shows that injecting cytokines into healthy individuals produces symptoms similar to a hangover. This supports the claim that excessive drinking can induce a body-wide inflammatory response, leading to hangovers.
Ethanol itself, before being metabolized into acetaldehyde, can also cause hangovers. Ethanol can irritate the stomach lining, leading to nausea and vomiting, and it can lower blood sugar and dilate blood vessels, causing headaches.
Congeners contained in alcohol can also cause hangovers. Congeners are compounds produced during alcohol fermentation, with methanol primarily cited as a cause of hangovers. In an experiment conducted by Dr. LF Chapman in 1970, the group that consumed alcohol high in congeners experienced hangovers at a rate 11 times higher than the group that did not. Although produced in small quantities during alcohol fermentation, methanol generates toxic byproducts like formaldehyde and formic acid, which damage cells.
Excessive lactate production during alcohol metabolism can cause lactic acidosis, potentially leading to muscle cramps associated with hangovers. Additionally, psychological factors like mood influence the severity of hangover symptoms.
How to resolve a hangover?
Having examined the various causes of hangovers, let’s now discuss methods to resolve them. First, to reduce hangover symptoms caused by acetaldehyde, one must either prevent its production or use methods that rapidly metabolize acetaldehyde. Many commercially available hangover remedies opt for the latter approach. Taking a hangover remedy containing an acetaldehyde dehydrogenase (ALDH) enhancer causes acetaldehyde to be rapidly broken down into acetic acid, alleviating the hangover. However, this method can lead to excessive acetic acid production, potentially increasing the risk of fatty liver disease and hyperlipidemia. Therefore, methods that suppress acetaldehyde production itself may be more effective for health. However, this method has the disadvantage of not addressing the effects of ethanol itself.
Another approach is to take anti-inflammatory drugs to alleviate the second cause: the inflammatory response. In fact, migraines, a common hangover symptom, occur due to increased concentrations of prostaglandins, which trigger inflammatory responses. Tolfenamic acid, an anti-inflammatory that suppresses this, is effective for treating migraines. Finnish scientists conducted experiments administering tolfenamic acid to heavy drinkers and confirmed significant hangover relief effects. Additionally, prickly pear cactus extract may help alleviate headaches, nausea, and fatigue.
The solution for the third cause, methanol, is somewhat paradoxical: drinking a little more alcohol to cure the hangover. The principle is that when methanol is metabolized, it causes a hangover; consuming additional ethanol at this point inhibits methanol metabolism and alleviates the hangover. However, caution is needed as this method can also promote the production of acetaldehyde.
Conclusion
A hangover after heavy drinking is a painful experience everyone has endured at least once. Yet it’s surprising how little academic research on hangovers exists globally. Reviewing various sources confirmed that acetaldehyde, ethanol, cytokines, and congeners are major causes of hangovers. We learned that controlling each cause offers ways to alleviate hangover symptoms. Comprehensively utilizing various relief methods can significantly reduce hangovers. Dan Rogers, author of ‘Proof, the science of booze’ published in the journal Nature, stated, “Even if there are drugs somewhat effective against hangovers, they are useless if you drink excessively. The most effective hangover prevention is not to drink alcohol.” With this somewhat obvious warning, I conclude this blog post.
