Saccharomyces boulardii: Protection Against Dysbiosis and Cognitive Decline

Several months ago I came across a paper[i] that really interested me on the probiotic yeast, Saccharomyces boulardii,  and its effect on cognitive declines associated with gut dysbiosis,  but I am so swamped with work that I never got a chance to read it.  Finally, at 11:30 pm Sunday night I decided enough was enough – the time had come.  (What I don’t do for all you biome fans…)

As you know from previous posts, the bacterial microbiome changes for the worse as we age, taking insult after insult:  antibiotics, poor diet, stress, medications, and so forth.  (Look here and here for just two posts on the topic.)  You know too that dysbiosis is known to lead to an increase in the gut of pro-inflammatory toxins from bad bacteria like LPS (lipopolysaccharides); inflammatory cytokines; increased intestinal permeability (i.e. leaky gut); and intestinal disorders.  To make a bad situation worse, we also know that increased LPS and inflammatory cytokines which enter circulation through the leaky gut contribute to mood disorders, neurodegenerative disorders and memory dysfunction.  (You can read more about that on The Biome Buzz as well:  here is just one example.)

Antibiotics and poor diet are considered the major causes of bacteria dysbiosis in the gut; we know too that probiotics like Lactobacillus and Bifidobacterium may “…improve central nervous system (CNS) functions altered by gut dysbiosis…” including showing neuroprotective effects against declines in learning and memory.   Little research though has been done looking at the effects of the probiotic yeast, Saccharomyces boulardii on age-related cognitive decline.  We already know that S. boulardii helps good bacteria establish themselves in the gut, has anti-inflammatory properties and also boosts IgA levels, which help keep pathogen levels down.  But more than that, according to this paper, S. boulardii also improves gut barrier dysfunction and restores normal levels of short-chain fatty acids by improving the quality of the gut bacteria.

Thus, these researchers decided to explore (in an animal model for reasons you will learn shortly) the effects of S. boulardii on cognitive decline brought on by dysbiosis.  They separated mice into four groups:  a control, a group which received antibiotics only; a group which received antibiotics along with S. boulardii; and a group which received S. boulardii alone.  The results were striking, as I’m sure you guessed.  Here are a few of the results:

  1. The mice who received antibiotics alone had a decrease in probiotic bacteria, while S. boulardii restored levels.
  2. Treatment with S. boulardii alleviated the signs of cognitive decline which were extremely apparent in the antibiotic-treated mice.
  3. S.boulardii also successfully reduced the oxidative stress shown in the antibiotic group, as well as significantly lowered inflammatory cytokine levels.
  4. Antibiotic-treated animals showed decreased density of neurons in the brain’s hippocampus (which is our main memory center), but S. boulardii protected the neurons.
  5. S.boulardii clearly protected against gut barrier dysfunction. It also may help in, “…the elimination of bacterial toxins, pathogen binding, and growth inhibition of microbial pathogens.”
  6. Finally, S. boulardii restored normal cognitive and memory function in animals treated with antibiotics.

Their conclusion then:  “S. boulardii which is an established probiotic yeast commonly prescribed against inflammatory bowel disease and antibiotic associated diarrhea is being shown for the first time to ameliorate gut dysbiosis associated cognitive decline in mice. Administration of S. Boulardii was associated with an increase in beneficial gut bacteria, restored intestinal barrier integrity, reduced inflammation and oxidative stress in both gut and brain, protecting the hippocampal cholinergic neurons and preventing gut dysbiosis associated cognitive decline.”   Yes, it’s an animal study, but as we already know that antibiotics cause similar issues in humans, taking S. boulardii seems to me to be one of those things you can do for yourself that can’t hurt, could help.


[i] Roy Sarkar S, Mitra Mazumder P, Chatterjee K, Sarkar A, Adhikary M, Mukhopadhyay K, Banerjee S. Saccharomyces boulardii ameliorates gut dysbiosis associated cognitive decline. Physiol Behav. 2021 Jul 1;236:113411. doi: 10.1016/j.physbeh.2021.113411. Epub 2021 Mar 31. PMID: 33811908.


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