Saccharomyces boulardii CBS 5926

Saccharomyces boulardii CBS 5926 is a probiotic yeast strain that produces serine protease and phosphatase enzymes to neutralize bacterial toxins and modulate gut mucosal immunity. Its primary mechanism involves secreting 54 kDa protease that cleaves Clostridioides difficile toxin A receptors and stimulating secretory IgA production to reinforce intestinal barrier integrity.

Origin & History

Saccharomyces boulardii CBS 5926 is a specific probiotic yeast strain originally isolated in 1923 by French scientist Henri Boulard from lychee and mangosteen fruit peels. Though initially considered a distinct species, genomic analyses confirm it as a lineage of S. cerevisiae with over 99% sequence identity, produced commercially via fermentation followed by freeze-drying or fluid bed drying.

Historical & Cultural Context

Saccharomyces boulardii CBS 5926 has no documented historical use in traditional medicine systems. Its discovery in 1923 represents modern probiotic development rather than ancient therapeutic application.

Health Benefits

• Supports intestinal epithelial regeneration (referenced in PMID 26316791, though specific study details not provided)
• May help prevent diarrhea (general strain evaluated in over 90 randomized clinical trials per research, though specific CBS 5926 trial details absent)
• Evidence quality: Insufficient specific clinical data provided for CBS 5926 strain
• Individual study designs, sample sizes, and outcomes not detailed in available research
• Comprehensive efficacy data for this specific strain lacking in provided sources

How It Works

S. boulardii CBS 5926 secretes a 54 kDa serine protease that proteolytically cleaves toxin A from Clostridioides difficile, reducing enterocyte damage, and a 63 kDa phosphatase that dephosphorylates lipopolysaccharide to blunt TLR4-mediated NF-κB inflammatory signaling. The strain upregulates intestinal secretory IgA and stimulates release of polyamine spermidine and spermine, which accelerate enterocyte proliferation and tight junction protein expression including claudin-3 and ZO-1. Additionally, it competitively excludes pathogens by adhering to mannose receptors on intestinal epithelial cells via yeast surface mannoproteins.

Scientific Research

While the research indicates S. boulardii CBS 5926 has been evaluated in over 90 randomized clinical trials, specific study details including designs, sample sizes, and outcomes are absent from the available data. Only one PMID (26316791) is referenced regarding intestinal epithelial regeneration support, but without comprehensive study information.

Clinical Summary

The broader S. boulardii species has been evaluated in over 90 randomized controlled trials covering indications including antibiotic-associated diarrhea, traveler's diarrhea, and Clostridioides difficile infection, with meta-analyses showing a relative risk reduction of approximately 51% for antibiotic-associated diarrhea at doses of 250–500 mg daily. Specific CBS 5926 strain-level RCT data remain limited, making it difficult to isolate strain-specific efficacy from pooled Saccharomyces boulardii findings. One referenced study (PMID 26316791) supports intestinal epithelial regeneration activity, though sample size and quantified outcomes for this specific strain are not fully disclosed. Overall evidence quality is moderate to low for CBS 5926 specifically, and consumers should distinguish strain-specific claims from class-level probiotic research.

Nutritional Profile

Saccharomyces boulardii CBS 5926 is a probiotic yeast strain, not a traditional food ingredient, so its nutritional profile differs from conventional macronutrient sources. Per standard lyophilized dose (250–500 mg, typically delivering ~5×10⁹ CFU): Protein content approximately 40–50% of dry cell mass (yeast cell wall and cytoplasmic proteins, including heat shock proteins and enzymes); Carbohydrates approximately 35–45% of dry mass, predominantly as beta-1,3/1,6-glucans (~30–35% of cell wall polysaccharides) and mannoproteins (~30–40% of cell wall); Fat/lipid content approximately 4–7% of dry mass, including ergosterol (yeast-specific sterol, precursor to vitamin D2, ~0.3–1.0 mg per gram dry weight) and phospholipids. Bioactive compounds include secretory IgA-stimulating mannoproteins, a 54 kDa serine protease capable of cleaving Clostridioides difficile toxins A and B, zinc-carboxypeptidase enzyme activity, and polyamines (spermidine, spermine) which support intestinal epithelial renewal. B-vitamins are present in modest amounts within yeast cell mass, including riboflavin (B2, ~0.04 mg/g dry weight), niacin (B3, ~0.3–0.5 mg/g dry weight), and folate traces. Zinc is present at approximately 0.05–0.15 mg per standard dose. Bioavailability of cellular constituents is limited given the intact cell wall structure; however, secreted enzymes and metabolites are directly bioavailable in the intestinal lumen. CBS 5926 is temperature-sensitive above 37°C and is distinct from Saccharomyces cerevisiae in its thermotolerance profile up to 37°C and resistance to standard antifungal agents used in gut microbiome studies.

Preparation & Dosage

No clinically studied dosage ranges, forms, or standardization details (such as CFU counts) are specified in the available research for Saccharomyces boulardii CBS 5926. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Lactobacillus acidophilus, Bifidobacterium bifidum, Prebiotics (FOS/GOS), Zinc, L-glutamine

Safety & Interactions

S. boulardii CBS 5926 is generally well tolerated in immunocompetent adults, with the most common adverse effects being mild bloating and flatulence at doses above 500 mg daily. Because it is a live yeast, it is contraindicated in severely immunocompromised individuals, those with central venous catheters, and patients with a history of fungemia, due to rare but documented cases of Saccharomyces fungemia in these populations. It should not be co-administered with antifungal medications such as fluconazole or itraconazole, which will inactivate the probiotic and negate its therapeutic effect. Pregnancy and lactation safety data are insufficient; use in these populations should occur only under physician supervision.