A single alcohol binge can cause bacteria to leak from the gut and increase levels of bacterial toxins in the blood, researchers said.
Increased levels of these bacterial toxins, called endotoxins, were shown to affect the immune system, with the body producing more immune cells involved in fever, inflammation, and tissue destruction.
Binge drinking is defined as a pattern of drinking alcohol that brings blood alcohol concentration (BAC) to 0.08g/dL or above.
For a typical adult, this pattern corresponds to consuming five or more drinks for men, or four or more drinks for women, in about two hours.
Some individuals will reach a 0.08g/dL BAC sooner depending on body weight.
Binge drinking is known to pose health and safety risks, including car crashes and injuries. Over the long term, binge drinking can damage the liver and other organs.
"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 such as bacterial leakage from the gut into the blood stream," said Dr George Koob, director of the National Institute on Alcohol Abuse and Alcoholism, part of National Institutes of Health (NIH).
In the study led by Gyongyi Szabo, from the University of Massachusetts Medical School, 11 men and 14 women were given enough alcohol to raise their blood alcohol levels to at least 0.08 g/dL within an hour.
Blood samples were taken every 30 minutes for four hours after the binge and again 24 hours later.
The researchers found that the alcohol binge resulted in a rapid increase in endotoxin levels in the blood and evidence of bacterial DNA, showing that bacteria had permeated the gut.
Endotoxins are toxins contained in the cell wall of certain bacteria that are released when the cell is destroyed. Compared to men, women had higher blood alcohol levels and circulating endotoxin levels.
"We found that a single alcohol binge can elicit an immune response, potentially impacting the health of an otherwise healthy individual," said Szabo.
"Our observations suggest that an alcohol binge is more dangerous than previously thought," said Szabo.
The research appears in the journal PLOS ONE.