Probiotic use in IBD may cloud the mind

Patients with inflammatory bowel disease (IBD) who consume probiotics can develop brain fog, especially men and those who are Caucasian, as suggested in a study.

Probiotics tout gastrointestinal benefits, such as improvements in gut barrier function and gut transit. So, it is not a surprise that IBD patients frequently consume probiotics, “whether sanctioned by a physician or not,” according to one of the study authors, Dr Apaar Dadlani of the University of Louisville in Kentucky, United States. [Nat Rev Gastroenterol Hepatol 2014;11:506-514]

“However, probiotic consumption, in itself, has been shown to increase the incidence of brain fog,” added Dadlani who presented the results of their study at the Advances in Inflammatory Bowel Diseases (AIBD) Annual Conference 2021.

Indeed, Dadlani pointed out that in their cohort of 66 adult IBD patients (mean age 44 years, 53 percent female, 89.4 percent Caucasian), the use of probiotics conferred an increased risk of brain fog compared with nonuse, although this was only observed among male (p=0.004) and Caucasian patients (p=0.004). [AIBD 2021, abstract 27]

Of note, the longer the duration of probiotic exposure, the greater the risk of brain fog (p=0.038).

Out of the 66 patients, 21 (31.8 percent) took probiotics as dietary supplements, with most of them (n=14, 67 percent) having been exposed to probiotics for over a year.

D-lactic acid culprit

Brain fogginess makes up a constellation of symptoms including mental confusion, impaired judgment, poor short-term memory, and difficulty with concentration, which is often transient and disabling. How probiotics can trigger this cognitive impairment has been postulated to involve the production of D-lactic acid.

Lactobacillus species and Bifidobacterium are the most common bacteria in probiotic formulations and have been shown to be useful in the treatment of intestinal problems including IBD. Both bacteria produce D-lactic acid in the small intestine as a by-product of breaking down food sugars. At high amounts, D-lactic acid gets absorbed in the blood and reaches the brain. [Nat Rev Gastroenterol Hepatol 2014;11:506-514; Expert Opin Drug Saf 2014;13:227-239; Am J Gastroenterol 2014;109:1547-1561]

A previous study provided evidence that probiotic consumption could result in a build-up of bacteria in the small intestine, contributing to brain fogginess as well as belly bloating. The findings showed that all the patients who experienced brain fogginess had been taking antibiotics, with the duration ranging from 3 months to 3 years. [Clin Transl Gastroenterol 2018;9:162]

Furthermore, patients who did vs did not experience brain fog had a greater prevalence of small intestinal bacterial overgrowth (68 percent vs 28 percent) and D-lactic acidosis (77 percent vs 25 percent). Brain fogginess resolved when patients discontinued probiotics and took a course of antibiotics. [Clin Transl Gastroenterol 2018;9:162]

“Given the high prevalence of probiotic use in IBD patients, prospective studies are warranted to examine the causal relationship between probiotics and IBD-associated brain fog to guide prescription of probiotic supplements for IBD,” according to Dadlani.