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People who have had stomach-stapling surgery are being warned to go easy on the booze after a study found they got drunk on just one glass of red wine.
"A lot of people think they can have one glass of wine and be okay," said Dr John Morton,
assistant professor of surgery at Stanford University Medical Centre, who is the study's lead author. "The concern here is they really can't."
Dr Morton has performed more than 1000 gastric bypass, or stomach stapling, surgeries.
He said he routinely warned his patients about drinking alcohol.
"I didn't find a whole lot in the literature, so that prompted the study," he said.
Dr John Wyeth, gastroenterologist at Wellington's Southern Cross Hospital, said doctors in New Zealand routinely advised patients who had obesity surgery operations about post-operation ill-effects of alcohol intake.
"Whenever you talk about alcohol, it gets quite complex because a lot of the effects of alcohol are really due to psychological factors, rate of absorption, previous exposure to alcohol, and tolerance levels."
So a predicted response to alcohol was almost impossible, Dr Wyeth said.
"However, the absorption of alcohol does involve the stomach and intestine, then being absorbed into the blood and going to the liver.
'What we are doing is interfering with part of the pathway. We are reducing some of the gastric volume, thus speeding up the level of alcohol absorption."
Dr Wyeth said the alcohol was going to be put through the small intestine faster, depending on the type of gastric operation.
"So there was a lot of potential for the normal breakdown of absorption metabolism of alcohol to be abnormal."
Moderation was the rule, Dr Wyeth said.
"We always advise patients who have the operation to go easy on alcohol. Alcohol has calories in it and the reason they have had the operation is to try and reduce the calorie intake."
Patients are advised to be prudent because "the effects of alcohol after the operation was going be different", he said.
The US research team gave 36 men and women - 19 of whom had obesity surgery and 17 who did not - 5oz (147ml) of red wine each to drink in 15 minutes.
Using a breathalyser, their alcohol level was measured every five minutes until it returned to zero.
More than 70 per cent of the surgery patients hit a blood-alcohol level of 0.08 per cent, which qualifies as legally intoxicated in California, and two reached levels above 0.15, Morton said.
By contrast, most of the control group had levels below 0.05 per cent, the study reported.
Researchers also found that obesity patients took longer to sober up.
Dr Morton said the obesity surgery patients did not produce as much of an enzyme that breaks down alcohol because their stomachs were smaller. Also, the alcohol passed to their small intestine faster, speeding up absorption, he said.
The findings highlight an important warning for obesity patients: "Never have more than a couple of glasses in a single sitting, and don't drive afterward," Dr Morton said.
- NZPA