One-Time Alcohol Binge Can Impair Immune System in Young Adults

Binge drinking can have a disruptive effect on the immune system of healthy young adults, according to a new study.

Much of the research on binge drinking has focused on the day after drinking, but the new study provides evidence of the same effects—that the body is less able to fight off an infection or injury—while alcohol is still in the drinker’s system.

Binge Drinking in the U.S.

The National Institute on Alcohol Abuse and Alcoholism defines a binge as any period of drinking that brings your blood-alcohol content up to 0.08 percent, which is the legal limit for driving. For a man, this is after about five drinks in two hours. A woman hits that threshold after about four drinks over the same time period. According to the Centers for Disease Control and Prevention (CDC), one in six U.S. adults binge drinks four times per month, and the practice is more common in young adults between the ages of 18 and 34.

Many of the negative effects of binge drinking are already known. For example, you’re more likely to fall, get burned, get shot or have a car accident when you’re binge drinking, and a third of all trauma patients have alcohol in their systems. Deaths from such injuries are also more common in binge drinkers. Existing evidence has shown that binge drinking increases the likelihood of pneumonia and infections resulting from catheters, increases blood loss and delays wound healing.

How Alcohol Affects the Immune System

The authors recruited a small sample of eight women and seven men for the study, with a median age of 27, each of whom drank enough vodka to raise their blood-alcohol levels over the threshold of a binge. In order to look at the impact of raised blood alcohol on the immune system, the researchers took blood samples 20 minutes, two hours and five hours after the participants had consumed the alcohol, as well as prior to drinking for comparison. The timing of the blood samples reflects the times drinkers ordinarily arrive at hospitals or trauma centers for treatment of binge-related injuries.

Drinking Decreases Immune System Activity

The researchers found that the effect of alcohol on the immune system changes over time after peak intoxication. At first—as measured at the 20-minute mark in the study—white blood cell levels (specifically leukocytes, monocytes and natural “killer cells”) were higher than they were at pre-drinking readings, indicating that the immune system of drinkers is initially boosted. Additionally, researchers noted higher levels of cytokines, which signal the immune system to kick into action. However, this effect was reversed at the two- and five-hour marks, which were both characterized by reduced monocyte and natural killer cell levels, as well as the presence of a different cytokines, which tell the immune system to become less active.

In basic terms, the study suggests that while there is an initial boost in immune system activity following binge drinking, the long-term effect is that it reduces activity levels to below pre-drinking levels, possibly allowing existing infections to affect the individual for longer or making new infections more likely.

This last point isn’t exactly clear from the study, though, because it was designed only to look at whether the immune system is negatively impacted by binging, not specifically whether this would lead to increased odds of catching a cold or the flu. This is especially difficult to determine because it’s hard to say how much of the risk is associated with a single episode of binge drinking and how much is related to ongoing drinking, which often leads to poor nutrition and other persistent health problems.

Lead author Dr. Majid Afshar explains that the study simply establishes that a single episode of binge drinking impacts the immune system, opening the door for future studies. “The point is that not everyone realizes that just one binge-drinking episode can be harmful.”

Uncovering More Risks of Binge Drinking

The new finding should serve as a warning that the impacts of a binge extend far beyond regrettable behavior and a hangover the next morning. The study shows that drinking excessively could affect your body’s ability to deal with infections, and a follow-up study that Dr. Afshar is conducting will investigate whether patients arriving at a burn unit with alcohol in their systems have less positive outcomes. This initial finding demonstrates that a single binge-drinking episode definitely impacts the immune system, but future research will confirm whether this effect leads to more serious consequences following an injury or infection.