Commonly, binge drinking is defined as consuming either five or more alcoholic beverages (for men) or four or more (for women) within about two hours. Now, a new study has found that a single alcoholic binge can cause bacteria to leak from your gut and increase the levels of toxins in your blood. Worse, this increased level of endotoxins, as they are called, triggers your immune system and so causes negative health effects. “Our observations suggest that an alcohol binge is more dangerous than previously thought,” said Dr. Gyongyi Szabo, professor and vice chair of medicine and associate dean for clinical and translational sciences at the University of Massachusetts Medical School.

Binge drinking is the most frequent form of alcohol consumption worldwide, a pattern of consumption most popular among underage drinkers and young adults. In the study, conducted by a team of researchers led by Szabo, 11 men and 14 women were given enough alcohol to raise their blood alcohol levels to at least .08 g/dL within an hour — this is a precise measurement for binge drinking experience (and is also above the legal driving limit). Blood samples were taken every 30 minutes for four hours after the binge and once again 24 hours later.

After analyzing the results, the researchers arrived at some unexpected conclusions. They observed, for instance, how the alcohol binge resulted in a rapid increase in endotoxin levels in the blood. Endotoxins are poisons contained in the cell wall of certain bacteria and these toxins are released whenever such cells are destroyed. Seeing evidence of bacterial DNA in the blood, then, the researchers understood that bacteria had permeated the gut.

The reason this is important is increased gut permeability and increased endotoxin blood levels have been linked to many health issues, including alcoholic liver disease. Plus, by triggering the immune system, the body begins the process of fever, inflammation, and tissue destruction. Over the long-term, binge drinking and the harm done by these immune system effects can damage the liver and other organs.

Also important, the researchers noted how women had higher blood alcohol levels and circulating endotoxin levels compared to the men.

“While the negative health effects of chronic drinking are well-documented, this is a key study to show that a single alcohol binge can cause damaging effects,” said Dr. George Koob, director of the National Institute on Alcohol Abuse and Alcoholism. The study was funded in part by the National Institutes of Health.

Source: Bala S, Marcos M, Gattu A, Catalano D, Szabo G. Acute Binge Drinking Increases Serum Endotoxin and Bacterial DNA Levels in Healthy Individuals. PLOS ONE. 2014.