ASBS: Alcohol Effects Altered after Bariatric Surgery

SAN DIEGO, June 15 -- Gastric bypass surgery alters alcohol metabolism -- as many surgeons and patients suspected -- leading to faster peaks and prolonged effects without an increase in symptoms, researchers found.

In a case-control study, blood alcohol concentration peaked about 0.03% higher and took 40 minutes longer to dissipate among patients who had undergone bariatric surgery than in those who had not (P=0.004 and P=0.001), reported John M. Morton, M.D., M.P.H, of Stanford University, and colleagues.

"Alcohol after gastric bypass surgery should be approached with caution," Dr. Morton said here at the American Society of Bariatric Surgeons meeting.

He decided to investigate when patients swamped his office with concerns prompted by a segment on Oprah Winfrey's television show that focused on women who became addicted to alcohol following weight-loss surgery.

"We've always kind of counseled patients to be careful with alcohol after surgery," Dr. Morton said. "I was surprised to see there wasn't much work in the area."

All of the factors involved in alcohol metabolism -- weight, liver function, food intake, and production of the enzyme alcohol dehydrogenase -- are "profoundly altered" by gastric bypass surgery, he said.

But only one prior study from Sweden had looked at the issue, and only in 11 women.

So, the researchers studied 19 patients who had undergone gastric bypass surgery at least a year before and 17 volunteers matched for age, gender, and weight who had not had bariatric surgery.

About 20% of participants in both groups were male. Drinking history and patterns were similar between groups. However, the surgery group was older (average 47 versus 37, P=0.023) and heavier (200.8 versus 149.8 lbs., P=0.0012).

After fasting for at least two hours, participants were asked to drink 5 ounces of red wine over a 15 minute period. The investigators measured their breath alcohol level initially then every five minutes until it reached zero.

They found that the patients who had undergone bariatric surgery had a higher peak breath alcohol level at 0.08% -- which is legally drunk in some states -- compared with 0.05% in the control group (P=0.004).

Furthermore, the gastric bypass group took almost 40 minutes longer to completely metabolize the alcohol (time to zero 108 versus 72 minutes, P=0.001).

Age- and weight-adjusted breath alcohol curves showed significantly higher levels at each time point for the gastric bypass patients compared with the controls.

Gastric bypass surgery was "by far the most significant predictor of time to return to zero for breath alcohol levels," Dr. Morton said, compared with the other significant predictors (gender, body mass index, and starting level).

Notably, patients reported no significant differences in symptoms between groups in a survey.

This was "a little bit disturbing because if these patients don't have feedback to know that their blood alcohol level is high they may be lulled into thinking that their alcohol is okay and keep drinking," Dr. Morton said.

Another implication, he added, is that they don't get the same "high" from alcohol as they did before surgery, which may contribute to "addiction transfer," or the substitution of one habit-eating-for another. In this case, drinking.

Overall, the findings suggest that patients undergoing gastric bypass surgery need to be counseled to approach alcohol intake after surgery with caution, he said.

"Can you can enjoy a glass of wine in your home? Absolutely," he said. "But you have to be aware that the alcohol level is going to be higher and stay higher longer than it did before surgery."

In a situation where patients would be driving, "even one glass of wine may be too much" after gastric bypass surgery, he said, and two is probably the limit.