Brain fogginess, gas and bloating: a link between SIBO, probiotics and metabolic acidosis.
Level 4 - case-series / case-control
Observational case-control comparison with an uncontrolled treatment cohort
PubMed 29915215 · doi:10.1038/s41424-018-0030-7
What was done
Researchers evaluated 38 patients with unexplained gas, bloating, an intact gastrointestinal tract, and negative endoscopic and radiological tests, comparing those with brain fogginess (n = 30) to those without (n = 8). SIBO was assessed using glucose breath tests and duodenal aspiration/culture. Metabolic testing included urinary D-lactic acid, blood L-lactic acid, and ammonia levels. Gastrointestinal transit and symptoms were evaluated. Patients with brain fogginess were treated by stopping probiotics and taking a course of antibiotics.
What was found
All 30 patients in the brain fogginess (BF) group consumed probiotics. SIBO was more prevalent in the BF group than the non-BF group (68% vs. 28%, p = 0.05), as was D-lactic acidosis (77% vs. 25%, p = 0.006). Brain fogginess was reproduced during testing in 20/30 (66%) patients. Slow gastrointestinal transit was found in 10/30 (33%) BF patients and 2/8 (25%) non-BF patients. Blood L-lactate and ammonia tests were unremarkable. After probiotic discontinuation and antibiotics, brain fogginess resolved and gastrointestinal symptoms improved significantly (p = 0.005) in 23/30 (77%) patients.
Why it matters
This paper identifies a clinical syndrome linking probiotic use, SIBO, and D-lactic acidosis to brain fogginess and bloating in patients without short bowel syndrome, offering a potential management strategy for an otherwise unexplained presentation.
Limits
The sample size is very small (n = 38 total, with only 8 non-BF controls). The intervention was open-label and uncontrolled, making it impossible to separate the effects of probiotic cessation, antibiotic therapy, natural history, or placebo effect.
Cited by
- supports Probiotics can worsen symptoms in people with ulcers who also have small intestinal bacterial overgrowth (SIBO).