medpage - Gastric Bypass Lowers Alcohol Tolerance

Physicians should warn gastric bypass patients that they may not be as tolerant of alcohol as they were prior to surgery, one researcher urged.

...The procedure may lead to metabolic changes that potentially affect the patient's sensitivity to even small amounts of drink, Peter Holt, MD, of Rockefeller University in New York City, wrote in a letter to The Lancet.

Holt said the data "mandate" that clinicians warn patients having Roux-en-Y gastric bypass surgery that they could experience "a major difference in their capacity to handle alcohol after their surgery." They also may want to consider not driving "after drinking any alcohol at all."

Most bariatric surgeons said they do warn patients that their tolerance for alcohol will change after the procedure.

"I tell them they will be a cheap date," Mitchell Roslin, MD, a bariatric surgeon at Lenox Hill Hospital in New York City, told MedPage Today in an email. He said alcohol is rapidly passed into the small bowel where it is quickly absorbed into the blood stream.

Richard Stahl, MD, lead gastrointestinal surgeon at the University of Alabama at Birmingham, told MedPage Today that he warns patients about the potential change in alcohol tolerance, but said it's likely that other clinicians aren't sufficiently educating patients.

In his letter, Holt briefly reviewed a number of studies on alcohol metabolism after gastric bypass and concluded that patients "should be very concerned about elevated blood (and breath) alcohol concentrations out of proportion to intake."

The changes may be due to alcohol-producing bacteria that accumulate in the bypassed duodenal-jejunal loop. It's been shown that bacteria accumulating in stagnant loops of intestine can produce ethanol from carbohydrates, Holt wrote.

In fact, one study showed that small amounts of alcohol have been detected in the blood of jejunoileal bypass patients and in obese women. Stahl noted that these concentrations, however, don't produce clinical effects. Thus, the patients don't feel intoxicated.

Another study found elevated peak alcohol concentrations and a significant delay in the return of alcohol levels to baseline concentrations after drinking just one glass of wine six months after surgery.

Stahl said it's easy to see why quick absorption into the bloodstream can increase blood alcohol concentrations rapidly, but it's not clear why it takes so long for those levels to subside.

Holt wrote that gastric bypass patients generally report greater sensitivity to small amounts of alcohol, with rapid intoxication and lower tolerance than before surgery.

He noted that the letter was prompted by one patient's misadventure from several years ago. The patient had a minor traffic accident and was given a breathalyser test, which indicated moderate intoxication.

The reading was much to the patient's surprise, Holt wrote, because many hours had passed since he had imbibed only one glass of wine.

Although gastric bypass patients are clearly told to lower their overall caloric intake in order to augment their weight loss, there are other foods besides alcohol that can have significant metabolic effects after surgery, such as sweets.

"Sweets are bad, and not just from a caloric standpoint," Stahl said. "They also cause dumping syndrome."

That's essentially the body's way of dealing with an overload of sugars that have rapidly crossed directly from the stomach into the bloodstream, he explained. It makes patients feel flushed and bloated and can increase heart rate.

"They just feel really awful, and it happens within minutes of eating that food," he said, adding that the initial symptoms are often followed a couple hours later with a second round due to low concentrations of blood sugar.

Primary source: The Lancet
Source reference: 
Holt RP "Changes in alcohol metabolism after gastric bypass surgery" Lancet 2011; 378: 767.

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