Drinking just four glasses of wine for women or five glasses for men in 2 hours - the official definition of binge drinking - may do more harm to a person's health than previously thought, according to new research.
Dr. Gyongyi Szabo and colleagues from the University of Massachusetts Medical School in Worcester report their findings in the journal PLOS ONE.
They found even a single alcohol binge drinking episode increases toxins in the blood - due to bacteria leaking from the gut - to levels that can trigger immune cells involved in fever, inflammation and tissue destruction.
Dr. Szabo says, "Our observations suggest that an alcohol binge is more dangerous than previously thought."
The National Institute on Alcohol Abuse and Alcoholism defines binge drinking as a pattern of alcohol consumption that raises blood alcohol concentration to 0.08g/dL or more.
For a typical adult, depending on their body weight, this can result from drinking five or more drinks for men, or four or more drinks for women, in one sitting lasting about 2 hours.
A drink is defined as 5 ounces (142 ml) of wine, 12 ounces (341 ml) of beer, or 1.5 ounces (43 ml) of spirits.
Binge drinking is already linked with increased risk of car crashes and injuries, and there is also evidence that it causes long-term damage to the liver and other organs.
Single binge drinking session can harm otherwise healthy individuals
Now this new study finds evidence to suggest just one binge drinking session can damage health. The damage results from bacteria leaking from the gut into the bloodstream and releasing toxins known as endotoxins.
Analyzing the participants' blood samples, the researchers found signs of rapid increases in endotoxins and evidence of bacterial DNA, indicating the bacteria had moved from the gut to the bloodstream.
"We found that a single alcohol binge can elicit an immune response, potentially impacting the health of an otherwise healthy individual," says Dr. Szabo.
For their study, the team invited 11 men and 14 women to consume alcoholic drinks that raised their blood alcohol to 0.08g/dL within an hour. They also took blood samples from the volunteers every half hour for 4 hours, then again 24 hours later.
When they analyzed the blood samples, the researchers found signs of rapid increases in endotoxins and evidence of bacterial DNA, indicating the bacteria had moved from the gut to the bloodstream.
The female participants showed higher blood alcohol levels and higher levels of circulating endotoxins.
Endotoxins are toxins that escape from the cell walls of certain bacteria when they die.
There is evidence that chronic alcohol use is linked to increased permeability of the gut, which allows harmful substances to get into the bloodstream and travel to other parts of the body.
Earlier studies have also linked greater gut permeability and higher levels of endotoxins in the blood to many of the health problems associated with chronic drinking, such as alcoholic liver disease.
Funds for the study came from the National Institute on Alcohol Abuse and Alcoholism, which is part of the National Institutes of Health.
According to the US Centers for Disease Control and Prevention, 38 million Americans drink too much. Only 1 in 6 Americans talk to their health professional about their drinking habits, says the federal agency, which urges doctors and nurses to make more use of alcohol screening and counseling.