Saccharomyces boulardii
Also known as: S. boulardii, Saccharomyces cerevisiae var. boulardii, CNCM I-745, Florastor strain, probiotic yeast
Saccharomyces boulardii is a probiotic yeast rather than a bacterium, originally isolated from lychee and mangosteen skins. Because it is a fungus, antibacterial antibiotics do not kill it, which is why it is the classic choice alongside antibiotic courses and in travel formulas. A 2010 systematic review and meta-analysis in adults covered antibiotic-associated diarrhea, traveler's diarrhea, and Helicobacter pylori adjunct trials, most using 250–500 mg (roughly 5–10 billion CFU) daily. It does not colonize permanently and clears within days after stopping.
Research summary
Studied for binding of bacterial toxins, support of intestinal enzyme activity, and modulation of inflammatory signaling; unaffected by antibacterial antibiotics.
Dosage
Daily amounts, of compound. CFU shown in billions.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 5 B CFU | 5–10 B CFU | — | — |
Amounts are in billions of CFU (enter 5 for 5 billion). Unlike bacterial rows, lyophilized S. boulardii is typically supplied at about 20 billion CFU per gram, so 5–10 billion CFU corresponds to roughly 250–500 mg of raw material (about 50 mg per billion CFU). Manufacturers add a 20–50% overage at fill; state CFU at manufacture or at expiry on the label. Can be taken during an antibiotic course without spacing.
Standardization: Lyophilized yeast; CFU per gram on CoA (commonly about 20 billion CFU/g)
Source material: freeze-dried culture
As supplied: Assumes about 20 billion CFU/g lyophilized yeast (50 mg per billion CFU), consistent with 250 mg ≈ 5 billion CFU; adjust to supplier CoA.
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Heat- and moisture-sensitive; capsule or dry powder only. More acid-stable than most bacterial probiotics.
Formulation notes
Antifungal drugs inactivate it; separate from antifungals. Not appropriate for immunocompromised users or those with central venous catheters because of rare fungemia reports. Unaffected by antibacterial antibiotics, so no dose spacing is needed.
Sources
Related ingredients
Probiotic Blend (Multi-Strain)
ProbioticA generic placeholder for a multi-strain probiotic blend, typically combining several Lactobacillus and Bifidobacterium species and sometimes Streptococcus thermophilus or a Bacillus spore.
Typical: 10–50 B CFU
Lactobacillus rhamnosus GG (LGG)
ProbioticLGG (Lactobacillus rhamnosus GG, ATCC 53103) is the single most studied probiotic strain, isolated in 1985 and since reclassified as Lacticaseibacillus rhamnosus.
Typical: 1–10 B CFU
Bifidobacterium lactis
ProbioticBifidobacterium animalis subsp.
Typical: 1–10 B CFU
L-Glutamine
Amino acidThe most abundant free amino acid in blood and muscle and a primary fuel for intestinal and immune cells.
Typical: 5–10 g
Lactobacillus acidophilus
ProbioticLactobacillus acidophilus is the most widely recognized probiotic species and a staple of yogurt cultures and multi-strain capsules.
Typical: 1–10 B CFU