Innate vs. Adaptive Immune System
To better understand the relationship between alcohol and the immune system let’s cover some background information. The main responsibility of the immune system is to protect the body from unwanted and possibly dangerous bacteria, viruses and other pathogens. To help achieve that we have a variety of cells, tissues and even organs, which we can divide into innate and adaptive.
Innate immune system
The innate immune system is the “muscle” of the immune system. This includes the physical and chemical barriers of our body against the outside world, for instance: skin, or mucous membranes. It consists of white blood cells (ex. macrophages), which engulf and get rid of any suspicious pathogens, but their response is nonspecific.
Adaptive immune system
The adaptive immune system, on the other hand, is the “brain” of the immune system. It relies on lymphocytes, namely T cells and B cells, which undergo a process of maturation and activation to recognize specific antigens present on the microorganims. These cells recognize and memorize specific pathogens, providing a more specialised defence to help our body fight reoccurring infections more effectively.
Alcohol and the Innate Immune System
Alcohol and immunity on a cellular level
Alcohol weakens our immune system response by decreasing the function of all immune cells in various ways and on various levels. These include:
- suppressing tissues’ ability to recruit immune cells in case of infection
- decreasing the rate of removal of invasive microorganisms, by reducing activity of neutrophils
- inhibiting the production of molecules needed for macrophages to digest and kill off bacteria
- affecting white blood cells, increasing the spread and propagation of pathogens
- producing specific proinflammatory proteins leading to tissue injury [1]
Since our immune system is responsible for protecting and “patrolling” the whole organism, its reduced efficacy appears in various organs and systems.
Alcohol and the digestive system
To be absorbed into the bloodstream, alcohol has to pass through the gastrointestinal (GI) tract, therefore making it especially vulnerable to its negative effects. One of them is destroying the balanced gut microbiome, which is essential for proper digestion. Damage to this delicate balance also causes decreased immune surveillance of the gut, leading to gastrointestinal infections caused by various pathogens.
Additionally, chronic alcohol use damages the epithelial cells lining the digestive system, as well as other immune cells, allowing bacteria and other pathogens to enter the bloodstream. This leads to chronic inflammation and contributes to a range of gut issues like inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and even liver damage [2].
The liver is one of the organs more susceptible to damage due to alcohol intake since it is the primary site of alcohol digestion. Chronic alcohol consumption impairs liver function and compromises its ability to not only metabolize alcohol, but also detoxify the body from any harmful substances putting more stress on the immune system. The dysregulated immune system health contributes to the progression of liver diseases such as alcoholic liver disease (ALD), hepatitis, and cirrhosis. Moreover, alcohol-induced inflammation and oxidative stress within the liver exacerbate tissue damage, perpetuating this vicious cycle.
A less recognized consequence of alcohol consumption is its influence on the gut-brain axis. The gut-brain axis is a link between the digestive system and the brain. Alcohol-induced changes in gut microbiota composition and intestinal barrier function can disrupt this communication, contributing to poorer mental health and mood disorders such as depression and anxiety. Moreover, dysregulated immune responses within the gut can further exacerbate neuroinflammation and cognitive impairment associated with chronic alcohol consumption.
Lastly, alcohol damages the mucus lining the stomach and intestines, which can impair nutrient absorption, leading to malnutrition or deficiencies in essential vitamins and minerals. These nutritional deficiencies further compromise immune function and exacerbate the negative effects of alcohol on overall health.
In summary, the decreased function of the immune system due to alcohol consumption has profound implications for digestive health, increasing the risk of gastrointestinal infections, impairing gut barrier function, exacerbating liver disease, disrupting gut-brain axis communication, and compromising nutrient absorption and digestive function.
Alcohol and the respiratory system
Alcohol-induced immune suppression compromises the lungs' ability to kill off respiratory pathogens, making patients more susceptible to infections such as pneumonia, tuberculosis, and influenza. Respiratory viruses, in particular, can pose a grave threat to individuals with weakened immune systems, which might lead to long-term complications. Chronic alcohol consumption amplifies inflammation within the airways, which exacerbates pre-existing lung conditions such as chronic obstructive pulmonary disease (COPD) and asthma.
Binge drinking can also cause acute respiratory distress syndrome (ARDS), also referred to as adult respiratory distress syndrome. It's a life-threatening condition characterized by severe lung inflammation and compromised oxygenation [3]. ARDS can be triggered by various factors, including pneumonia, sepsis, and trauma, all of which pose heightened risks in individuals with compromised immune system health due to alcohol consumption.
The respiratory tract's defence mechanism relies on mucociliary clearance, whereby cilia-lined epithelial cells push out pathogens trapped in mucus out of the airways. Alcohol disrupts the coordinated beating of cilia, which decreases the lung's ability to expel harmful particles and microorganisms, therefore increasing the probability of infection.
In short, excessive drinking damages immune cells present in the respiratory system, which increases the likelihood of airborne bacteria entering the lungs leading to respiratory infections. Similarly to the GI tract, alcohol also damages the epithelial cells of the lungs, increasing the risk of life-threatening complications such as ARDS, with symptoms such as severe and chronic shortness of breath, unusually rapid breathing and extreme tiredness and confusion [4].
Alcohol and the Adaptive Immune System
The opposing effects of heavy alcohol consumption on our immune system response also spread into the adaptive branch of the immune system. Chronic drinking has been proven to:
- interfere with the development and function of lymphocytes
- impair activation of T-cells, resulting in decreased long-term protection against specific microorganisms
- decrease efficiency of CD8+ cells responsible for clearing off any viral infection
- increased levels of CD8 protein in the blood, leading to more progressive hepatitis C infections and decreased reaction to the condition’s treatment
- reduced number of B-cells, therefore a decreased ability to produce antibodies
- activates cytokines, molecules essential to immune regulation. This increases the inflammatory response and might even lead to tissue damage [5].
How long does it take for the immune system to recover from alcohol?
The extent of immune system impairment due to alcohol consumption varies depending on factors such as frequency and quantity of consumed alcohol, as well as individual susceptibility. Therefore the data on the recovery time of a weakened immune system is quite varied. Some papers show that drinking 5 or 6 drinks in one session causes suppression of the immune response for around 24 hours [6]. At the same time, other studies show that it takes the innate cell activity up to 2 weeks after alcohol consumption to return to normal [7]. However, in the case of chronic heavy alcohol drinking, the suppressed immune response lasts for up to even 9 months [8].
Does alcohol have any positive effects?
For years moderate alcohol consumption has been glorified as somewhat beneficial. We've all probably heard of drinking red wine "for the antioxidants". There have been multiple myths created by obscure studies saying that moderate drinking of polyphenolic-rich alcoholic beverages, like wine or beer, can help with digestion, decrease the probability of infections, or even reduce the risk of heart disease or diabetes.
With more research done over the years now, we know that no amount of alcohol is safe, let alone positive for our health.
As the World Health Organization informs on their website: "It is the alcohol that causes harm, not the beverage". Apart from having negative effects on the immune response it is also rated a Group 1 carcinogen and is as dangerous as radiation or tobacco. It's been reported that alcohol is a cause of 4% of all cancers in 2020 [9], while almost half of them in the European Region have been caused by light or moderate alcohol consumption. [10].
Additionally, the World Health Organization also warns that alcohol is "a substance with dependence-producing properties", meaning it can lead to alcohol addiction or alcohol abuse, especially when it accompanies us in social situations.
Excessive alcohol consumption is destructive to our health, regardless of the alcohol content of our drinks of choice. The problem is ethanol, which is contained in all alcoholic beverages. There is no threshold of alcohol consumption where it's safe. The only certainty is the more we drink, the more harm we're exposed to.
What is the recommended amount of alcohol?
As mentioned before, any alcohol consumption is dangerous and might lead to alcohol use disorder, but if you're currently a regular drinker and want to limit your alcohol intake to take care of your health, these are the guidelines you should follow:
- women: no more than 1 drink/day, or 7 drinks/week
- men: no more than 2 drinks/day, or 14 drinks/week [11].
Additionally, incorporating healthy lifestyle practices such as regular exercise, adequate sleep, consuming a balanced diet rich in immune-boosting nutrients and proper hydration can further support your immune resilience and overall wellness. If you or any of your loved ones are struggling with alcohol addiction a good first step is to see your healthcare provider and ask for any resources available to you.
Conclusion
In conclusion, while alcohol may offer temporary relief or social enjoyment, its long-term repercussions on our immune health demand careful consideration. Heavy drinking negatively affects immune function, by lowering the efficacy and rate of production of various immune cells. This decreased protection against pathogens and lowered ability to cope with already-existing infections can last up to months, depending on the dose of alcohol ingested by the patient and their rate of alcohol metabolism. We must remember that alcohol is the leading risk factor for disability as well as premature mortality and causes 10% of deaths in the 15-49 age range. Understanding the relationship between alcohol and our heatlh, but also the immune system is essential to making informed choices and prioritizing our overall health and well-being [12].