Gastric Bypass Lowers Women's Alcohol Tolerance

Women who underwent gastric bypass surgery for weight loss are twice as susceptible to alcohol, according to a new study.

Researchers at Washington University School of Medicine (WUSTL; St. Louis, MO, USA) conducted a study to evaluate the effect of Roux-en-Y gastric bypass (RYGB) surgery on the pharmacokinetics and subjective effects of ingested alcohol, using arterialized blood samples and a validated questionnaire. The study involved 17 obese women, 8 of whom had undergone RYBG surgery one to five years before the study began, while the other 9 had not yet had the operation. The average body mass index (BMI) of the gastric bypass group was 30, while that of control group was 44.

The women spent two days (about one week apart), at the WUSTL research center. On the first visit, each woman randomly consumed either the equivalent of two alcoholic drinks or two nonalcoholic beverages during a 10-minute period. At the second visit, each woman was given the beverages not received during the first visit. At both visits, the researchers measured the women's blood-alcohol contents and used a survey to assess their feelings of drunkenness.

The results showed that among the women who had not undergone surgery, blood-alcohol content peaked about 25 minutes after they finished consuming the alcohol, and measured 0.60. In women who had RYGB surgery, blood-alcohol content peaked five minutes after drinking and reached 1.10, significantly higher than the legal driving limit in the United States of 0.80. The women who had undergone RYBG also reported feeling the effects of alcohol earlier and for longer periods of time than women who had not had the surgery. The study was published on August 5, 2015, in JAMA Surgery.

“We need to warn patients who have gastric bypass surgery that they will experience changes in the way their bodies metabolize alcohol,” said lead author M. Yanina Pepino, PhD. “Consuming alcohol after surgery the way one did before the operation could put patients at risk for potentially serious consequences, even when they drink only moderate amounts of alcohol.”

“After just two drinks, the blood-alcohol content in the surgery group exceeded the legal driving limit for 30 minutes, but the levels in the other group never reached the legal limit,” said senior author Prof. Samuel Klein, MD, director of the WUSTL Center for Human Nutrition. “The peak blood-alcohol content in the surgery group also met the criteria that the National Institute on Alcohol Abuse and Alcoholism uses to define an episode of binge drinking, which is a risk factor for developing alcohol problems.”

Although the study included only women, the researchers stressed that it is likely that men who have RYGB surgery experience similar changes in how their bodies metabolize alcohol.

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