Disclosures: The authors report no relevant financial disclosures, although Rao reports he has served as a consultant for Forest Laboratories, Ironwood Pharmaceuticals, Takeda, Salix, and Given Imaging.

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Probiotics linked to brain fog, severe abdominal bloating

Using probiotics can lead to bacterial growth in the small intestine, causing brain fog and rapid abdominal bloating, according to research published in Clinical and Translational Gastroenterology.

In a press release, Satish S.C. Rao, MD, PhD, FRCP, of the division of gastroenterology and hepatology of the Medical College of Georgia at Augusta University, said he and his colleagues found large colonies of bacteria in patients’ small intestine that were producing high levels of D-lactic acid. While probiotics have been linked to D-lactic acid and brain fogginess in patients with short bowel syndrome, Rao said this appears to be the first time it has been documented in patients with an intact gut.

“This is the first inroad,” he said in the press release.

For the study, Rao and colleagues sought to determine if brain fog, gas and bloating were associated with D-lactic acidosis and small intestinal bacterial overgrowth (SIBO).

They evaluated 30 patients with gas, bloating, brain fog and negative endoscopic and radiological tests, as well as eight patients without brain fog. They checked for SIBO using a glucose breath test and duodenal aspiration/culture and collected urinary D-lactic acid, blood L-lactic acid and ammonia levels.

Research has linked probiotic use with brain fog and severe abdominal bloating. Source: Shutterstock.com

Research has linked probiotic use with brain fog and severe abdominal bloating. Source: Shutterstock.com

The most common severe symptoms among patients were abdominal bloating, pain, distension and gas. All patients in the brain fog group consumed probiotics.

Rao and colleagues found that SIBO was more prevalent in the brain fog group compared with the non-brain fog group (68% vs. 28%; P = .05), as was D-Lactic acidosis (77% vs. 25%; P = .006).

Investigators reproduced brain fog in 22 of 30 patients after they underwent an overnight fast and consumed 75 g of glucose.

After discontinuing probiotic use and completing a course of antibiotics, 23 of 30 patients reported that their brain fog was resolved, and their gastrointestinal symptoms improved significantly (77%; P = .005).

Rao said the risk for SIBO and D-lactic acidosis should show that probiotics need to be treated as a drug, not as a food supplement.

“What we now know is that probiotic bacteria have the unique capacity to break down sugar and produce D-lactic acid,” he said in the press release. “So, if you inadvertently colonize your small bowel with probiotic bacteria, then you have set the stage for potentially developing lactic acidosis and brain fogginess.” – by Alex Young

Disclosures: The authors report no relevant financial disclosures, although Rao reports he has served as a consultant for Forest Laboratories, Ironwood Pharmaceuticals, Takeda, Salix, and Given Imaging.