Saccharomyces boulardii

What is it?

A probiotic yeast, Saccharomyces boulardii is used as a coadjunct in gastrointestinal disorders.

It is considered a variant or strain of S. cerevisiae. Physiologically, it differs from other common yeasts in its optimal growing temperature (around 37ºC), greater resistance to the acid pH of the stomach and to biliary degradation, and in its ability to pass through the intestine without permanently colonizing it while exercising a beneficial effect in its transit.

It is one of the most studied and used probiotic yeasts clinically and in dietary supplements.

Physiological functions

Saccharomyces boulardii acts in the intestine through various mechanisms that help to maintain the digestive function and reduce the intensity and duration of diarrheal processes. During its transit through the gastrointestinal tract, this probiotic yeast contributes to preserving the integrity of the intestinal barrier, helping to maintain the tight junctions between epithelial cells and reducing abnormal permeability that facilitates fluid loss and inflammation.

Additionally, S. boulardii interferes with the adhesion and colonization of pathogens, either by binding directly to bacteria like Salmonella or Escherichia coli, contribisuting to their elimination, or by secreting substances that make it harder for them to attach to the mucosa.

Another important function is modulation of the immune and local inflammatory response. S. boulardii is capable of attenuating excessive production of proinflammatory cytokines (like IL‑8, TNF‑α) by interfering with key signaling pathways (NF‑κB, MAPK), and at the same time promotes anti-inflammatory mediators (IL‑10, IL‑4), which helps to balance the host’s response to infections and dysbiosis.

Furthermore, it has trophic effects on the intestinal epithelium, improving nutrient absorption, which is especially relevant in situations of diarrhea or following treatment with antibiotics.

In addition, S. boulardii increases the proportion of Bifidobacterium spp, which is associated with a reduction in the risk of preeclampsia, high-risk birth, and vaginitis, vaginosis, and similar. In patients with a pre-pregnancy history of dysbiosis conditions such as vaginitis, vaginosis, periodontitis, it is especially interesting to increase bacterial diversity with scFOS and S. boulardii.