SOURCES: Samuel Klein, M.D., director, Center for Human Nutrition, Washington University School of Medicine, St. Louis; John Morton, M.D., chief, bariatric and minimally invasive surgery, Stanford University School of Medicine, Palo Alto, Calif., and president, American Society for Metabolic and Bariatric Surgery; Aug. 5, 2015, JAMA Surgery, online
WEDNESDAY, Aug. 5, 2015 (HealthDay News) -- People who have the most popular type of weight-loss surgery are far less able to handle alcohol after their procedure, a small, new study suggests.
"This surgery literally doubles the amount of alcohol that immediately enters your bloodstream," explained study author Dr. Samuel Klein, director of the Center for Human Nutrition at Washington University's School of Medicine in St Louis.
"And it also increases the patient's long-term risk for alcoholism, because the risk for a binge episode of drinking goes up. And we know that binge drinking increases the risk for going on to develop alcoholism in the future," Klein said.
The finding stems from an analysis involving 17 obese women. Eight had undergone Roux-en-Y gastric bypass surgery from one to five years before the study began, while the other nine women had not yet had the operation.
Klein and his colleagues reported their findings online Aug. 5 in the journal JAMA Surgery.
The U.S. National Institute of Diabetes and Digestive and Kidney Diseases explains that the surgery, often called "gastric bypass," divides up the stomach and small intestine, to restrict and redirect food absorption.
Following surgery, less food is consumed and what is taken in no longer comes into contact with the stomach, duodenum or upper intestine.
Though other surgical options exist for weight loss, the researchers noted that Roux-en-Y is currently the most commonly performed weight-loss ("bariatric") procedure in the world.
In the study, all of the women were asked to consume either the equivalent of two standard alcoholic drinks or two non-alcoholic "dummy" drinks in two 10-minute drinking sessions conducted about a week apart.
Rather than using the kind of breathalyzer technology typically used by roadside police, the authors measured blood alcohol concentration (BAC) levels. "Drunkenness" was clinically assessed by matching each participant's behavior to an "Addiction Research Center Inventory" checklist.
The result: BAC levels rose much faster among those in the bypass group, and ultimately peaked at levels pegged at twice those seen among those in the non-bypass group.
What's more, BAC levels among the bypass group exceeded legal driving limits for a half-hour following drink consumption. BAC levels never exceeded legal driving limits among the non-bypass group.
Feelings of drunkenness were also greater among the bypass group. And according to criteria established by the U.S. National Institute on Alcohol Abuse and Alcoholism, the team concluded that just two drinks put the bypass patients into the equivalent of a binge-drinking episode that could potentially raise the risk for long-term alcohol addiction.
Klein stressed that the laboratory methods he and his colleagues used were more rigorous and definitive than what has been used in previous studies looking at the issue.
But the finding isn't really novel, said Dr. John Morton, chief of bariatric and minimally invasive surgery at the Stanford University School of Medicine in Palo Alto, Calif.
"This is a very well-known phenomenon. We've known about this for quite a while," he countered.
"It's about physiology, and we certainly do let patients know ahead of time about the enhancement of alcohol sensitivity following this procedure, which happens because we have alcohol receptors in the stomach and the liver. And if you bypass and remove a portion of either of these, you have a change in blood alcohol levels," Morton said.
"But that's not peculiar to bariatric patients," added Morton, who is also president of the American Society for Metabolic and Bariatric Surgery. "That would happen following any kind of gastrointestinal surgery."
And, he explained, "at the same time, this is a phenomenon we only see with this specific type of bariatric surgery. You don't see it with gastric band or other weight-loss surgeries. And I also don't think it's the case that the theory being offered that this phenomenon can lead to binge drinking is actually what we see happen in practice."
There's more on bariatric surgery at the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.