Excessive consumption of alcoholic beverages has long been associated with a greater risk of infection and corollary health issues - but the breadth of this inebriant’s impact upon the human immune system might surprise you. In the age of COVID, managing immune health is of paramount importance. Recent research on COVID-19 patients has determined mortal complications, including pneumonia, to be more likely in the face of preexisting conditions if you catch SARS-CoV-2. Aside from short-term personal safety, maintenance of the immune system is also critical in order to ensure that our bodies produce an optimal response to vaccination. With all of this in mind, it behooves us to learn about the effects of alcohol intake on our ability to fight infections and how we can manage it. 

Let’s begin by breaking down how our immune system normally works. The cells and molecules that coordinate defense against pathogens can be divided into two groups: the innate immune system and the adaptive immune system. The former is responsible for your body’s initial reaction to intrusion and includes preventative mechanisms like mucous membranes, skin, and stomach acid. Affiliated white blood cells include phagocytes that attack and consume invaders, and dendritic cells that respond to molecules associated with pathogens by triggering an inflammatory response and handing signal molecules to T and B lymphocytes of the adaptive immune system. This latter group is responsible for attacks specific to certain viruses and bacteria. There are various types of T-cells, responsible for compounding or mitigating the inflammatory response, producing cytokines, and destroying infected and/or cancerous cells. B-cells are responsible for producing antibodies - proteins which mark a specific pathogen for removal. These proteins circulate in the blood for long periods after the threat has been removed - which is how vaccines produce immunity. 

Although research into the mechanisms of interaction is still ongoing, studies have shown that excessive consumption of alcoholic beverages is responsible for damage to innate and adaptive immune response. 

In terms of innate immunity, alcohol damages the endothelial lining of the gastro-intestinal tract, making it harder for these cells to coordinate immune responses with the rest of the body and easier for pathogens to penetrate the endothelium. This is also true of the lower respiratory tract, where alcohol damages the mucous membranes of the alveoli (the small tissue sacs which facilitate the exchange of CO2 and oxygen) making one more susceptible to respiratory infections like tuberculosis and pneumonia - both of which are associated with a greater likelihood of COVID-related mortality. Exposure to alcohol can also interfere with the cytokines responsible for controlling inflammation - acute exposure generally correlates with decreased immune response while  prolonged exposure may cause runaway inflammation that can potentially damage your organs, especially the heart and liver.

Unmanaged drinking hampers your body’s adaptive immune response as well. Studies of innate immune factors following short-term and prolonged exposure to alcohol have revealed a reduced capacity to activate T-cells - which are crucial to eliminating pathogens as the inflammatory response is rarely sufficient on its own. The T-cells themselves are also affected. One BBC researcher conducted an experiment where they consumed six units of alcohol in one sitting (defined by the UK’s public health advisory as a binge) and found their lymphocytes reduced by 20-30% within 12 hours. 

Taken together, all of this data makes it clear that moderating alcohol consumption is of utmost importance in ensuring that our bodies are in good shape to fight infection and maintain prolonged immunity. This does not mean that it is necessary to avoid consuming alcohol altogether. There is a substantive body of research suggesting that moderate alcohol consumption could actually result in an improved immune response as well as a lower risk of heart disease and certain cancers relative to abstainers. This does not, however, mean that making consumption infrequent is enough to remain in good health. As aforementioned, infrequent binge-drinking is correlated with a depressed immune system, and becoming accustomed to such patterns has the potential to create dependency and increase the likelihood of sudden death. The Dietary Guidelines for Americans define moderate drinking as up to a drink a day for women and two per day for men although everyone’s tolerance is different. If you believe that you might need help managing your alcohol intake or want to know more about how changes in lifestyle could affect your immunity, it might be advisable to consult with a physician or medical professional.