Regular alcohol consumption increases an individual's vulnerability to developing bacterial overgrowth in the small intestine, which can cause abdominal pain and malnutrition in severe cases, according to a recent study led by Scott Gabbard '02, a gastroenterology fellow at Dartmouth-Hitchcock Medical Center. The study also found that consuming only one or two drinks a day is strongly related to poor gastrointestinal health, DHMC Gastrointestinal Motility Lab Director Brian Lacy, who also worked on the study, said.
Although past research on the causes of bacterial overgrowth focused solely on chronic alcoholics, this study, presented at a medical conference on Oct. 30, shows a strong correlation between a relatively low consumption of alcohol and bacterial overgrowth, according to Gabbard.
"Patients who drank any alcohol had a 50 percent higher chance of having bacterial overgrowth than those who were complete abstainers," Gabbard said.
The number of diagnosed cases of small intestinal bacterial overgrowth, or SIBO, has risen recently and the topic remains controversial within the field of gastroenterology, Gabbard said.
Gabbard and his colleagues examined the effects of multiple lifestyle factors including smoking and alcohol consumption and medical factors such as prior surgery and medication while conducting their study, he said. The team, which also included researchers at the Mayo Clinic in Rochester, Minn., examined medical charts of 198 DHMC patients who had been diagnosed with SIBO between 2008 and 2010, he said.
"Smoking was not at all associated with bacterial overgrowth," Gabbard said. "Alcohol use was the strongest predicting factor for having a positive test for bacterial overgrowth."
Although alcohol is not the only cause of bacterial overgrowth, even small amounts of alcohol assumption can exacerbate the condition, according to Gabbard. Over 95 percent of the patients studied reported that they were moderate drinkers, which are defined as women who have up to one drink per day and men who have up to two per day, according to the U.S. Department of Agriculture. The number of people who identify as moderate drinkers may be growing, according to Lacy, who is also a Dartmouth Medical School professor.
Recalling his own college experience, Gabbard acknowledged that the definition of moderate alcohol consumption may seem low to Dartmouth students, who often reach or exceed this limit on a regular basis. Dartmouth students who consume alcohol at moderate levels especially those who have been previously diagnosed with bacterial overgrowth may be at risk for developing or worsening the syndrome, Gabbard said.
"I don't want to change anyone's lifestyle," he said. "However, their alcohol intake could be a risk factor for them given their history of bacterial overgrowth."
Because the study examined medical charts after patients' treatments and patients could not be asked detailed questions about their alcohol use, it remains unclear whether bacterial overgrowth is affected by the type of alcohol consumed or whether bacterial overgrowth could be treated by lowering consumption, Gabbard said.
Gabbard presented his findings to gastroenterology leaders at the 76th Annual Scientific Meeting of the American College of Gastroenterology in Washington, D.C., on Oct. 30, he said.
"Most people were surprised that such a moderate amount of alcohol could have such a profound effect," Gabbard said. "Hopefully, this will get some gears started."
Many conference attendees approached Gabbard after his presentation to further inquire about the findings, Lacy said.
"Nobody had really thought about it before," Lacy said. "They thought it was a neat addition to the literature."
