Just one drink per day for women -- two for men -- could lead to small intestinal¹ bacterial² overgrowth (SIBO小肠细菌过度生长) and subsequently cause gastrointestinal（胃肠的） symptoms like bloating, gas, abdominal³ pain, constipation（便秘） and diarrhea（腹泻） , according to the results of a new study unveiled at the American College of Gastroenterology's (ACG) 76th Annual Scientific meeting in Washington, DC. The retrospective review, "Moderate Alcohol Consumption is Associated with Small Intestinal Bacterial Overgrowth," looked at the charts of 198 patients who underwent lactulose（乳果糖） hydrogen breath testing (LHBT) to determine the presence of SIBO, and found that any current alcohol consumption was significantly associated with the presence of SIBO -- and neither smoking nor use of heartburn drugs called PPIs was associated with an increased risk of SIBO.

Small intestinal bacterial overgrowth is a condition where abnormally large numbers of bacteria grow in the small intestine⁴. Normally the small intestine contains a relatively⁵ low number of bacteria in contrast to the large intestine, which should contain a larger number of bacteria. In patients with SIBO, the abnormally large numbers of bacteria in the small intestine use for their growth many of the nutrients⁶ that would otherwise be absorbed.

As a result, a person with small bowel⁷ bacterial overgrowth may not absorb enough nutrients and become malnourished. In addition, the breakdown⁸ of nutrients by the bacteria in the small intestines⁹ can produce gas as well as lead to a change in bowel habits.

While previous studies have focused on alcoholics¹⁰, who were found to have high rates of SIBO, this study by Scott Gabbard, MD and colleagues at the Dartmouth-Hitchcock Medical Center and the Mayo Clinic, is one of the first to look at the relationship between moderate alcohol consumption and SIBO. Moderate alcohol consumption means no more than 1 drink per day for women and 2 drinks per day for men, with twelve ounces of regular beer, 5 ounces of wine, or 1-1⁄2 ounces of 80-proof distilled¹¹ spirits counting as one drink, according to the USDA dietary guidelines.

An overwhelming majority (95 percent) of the 198 patients in the study drank a moderate amount of alcohol, sometimes less than 1 drink per day, said Dr. Gabbard, who also indicated that only four of the patients drank more alcohol -- a finding he noted¹² indicates that consumption of even the slightest amount of alcohol could have an impact on gut¹³ health.

"These findings are significant because we now know that any bit of alcohol consumption--not just the amount consumed by alcoholics -- is a strong predictor of a positive lactulose hydrogen breath testing and small intestinal bacterial overgrowth," he said. "While typical treatment for SIBO has been antibiotics¹⁴, probiotics or a combination of the two, the question now becomes what is the exact association between moderate alcohol consumption and SIBO and whether alcohol cessation can be used as a treatment for this potentially harmful condition."