Saccharomyces boulardii is a nonpathogenic species of yeast (92807,92808). It is used in some food processes that require fermentation (92808). It is also commonly used in probiotic supplements (92807). Probiotics are live microbes that are viable in foods or as a food ingredient and that have confirmed health benefit (90605). Although S. boulardii was previously identified as a unique species of yeast, it is now classified as a strain of Saccharomyces cerevisiae (1227,1251,1282,7353).

WARNINGS

Coronavirus disease 2019 (COVID-19): Despite claims to the contrary, there is no good evidence to support using Saccharomyces boulardii for COVID-19. Recommend healthy lifestyle choices and proven prevention methods instead.

LIKELY SAFE ...when used orally and appropriately for up to 15 months (155,4347,4350,4351,4352,4353,4354,7140,7646,7652),(12763,14334,14379,14380,14381,72194,72198).

CHILDREN: POSSIBLY SAFE ...when used orally and appropriately (4347,4356,14334,72145,92806,98734,103451,107603,107605,111102)(111103).

PREGNANCY AND LACTATION: Insufficient reliable information available; avoid using.

•  Gastrointestinal

  Rarely, oral use of Saccharomyces boulardii has caused gastrointestinal complaints, such as abdominal cramps, flatulence, nausea, vomiting, and decreased appetite (98731,107608).

•  Immunologic

  Rarely, oral use of Saccharomyces boulardii has been associated with fungemia in both immunocompromised and immunocompetent patients (1247,4357,4358,4360,7329,14459,72121,72126,72142,92809,95357,95363)(96277,105171,107604,107607). Numerous cases of Saccharomyces fungemia have been reported in critically ill intensive care unit (ICU) patients, particularly those with indwelling or central venous catheters, those receiving enteral feeding, or those receiving broad-spectrum antibiotics. Most infections occurred when packets of Saccharomyces were used or when Saccharomyces capsules were opened at the bedside (12776,12777,14459,95358,95360,95362,95363,105171). Admission to the ICU and extended length of stay increase the risk of developing Saccharomyces fungemia (107604). In a hospitalized 1-year-old patient with severe malnutrition and multiple invasive devices, Saccharomyces cerevisiae fungemia developed 2 days after receiving a probiotic containing S. boulardii 200 mg twice daily for 4 days (96277). In addition, there are two case reports of S. cerevisiae fungemia in hospitalized and intubated older patients with COVID-19 who had been given S. boulardii for diarrhea (105171).
  
  The true incidence of fungemia is difficult to determine with S. boulardii. Most clinical laboratories are unable to differentiate between S. boulardii and S. cerevisiae, which might come from other sources (7353). In two case reports of patients in the ICU, there was a 100% alignment of fungal ribosomal DNA ITS sequences between the strains found in the blood of the infected patients and the strains of S. boulardii that had been administered (105171). In a large analysis of hospitalized patients, the incidence rate of Saccharomyces fungemia was 0.11% of those given S. boulardii and did not occur in patients not given this probiotic. Packets or capsules opened at a distance from the patient in the hospital were included in this analysis (107604).
  
  Positive Saccharomyces cultures have also been obtained rarely from other sites, such as the abdominal region and the oral or respiratory tract (107607).
  
  An elevated erythrocyte sedimentation rate may occur when S. boulardii is used to treat Crohn disease (7646), but this effect may be a natural part of the disease process.

• Adult

  Oral:

  Saccharomyces boulardii has most often been used in doses of 500-1000 mg (about 10-20 billion colony-forming units) for up to 4 weeks. See Effectiveness section for condition-specific information.

• Children

  Oral:

  Saccharomyces boulardii has most often been used in doses of 250-500 mg (about 5-10 billion colony-forming units) for up to 4 weeks. In infants, doses of 50-200 mg/kg daily for up to 28 days have most often been used. See Effectiveness section for condition-specific information.

• Standardization & Formulation

  Saccharomyces boulardii is commercially available as lyophilized (dried) cells in capsule forms in most countries (72190). Powders have also been used in clinical trials (103451).

ANTIFUNGALS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking antifungals with Saccharomyces boulardii might decrease the effectiveness of Saccharomyces boulardii.  Details S. boulardii is a live yeast. Therefore, simultaneously taking antifungals might kill a significant number of the organisms (4363).

 CENTRAL VENOUS CATHETERS

 ELDERLY

 GASTROINTESTINAL TRACT DISEASE

 IMMUNODEFICIENCY

 YEAST ALLERGY

There is insufficient reliable information available about the presentation or treatment of overdose with Saccharomyces boulardii.

Absorption: Saccharomyces boulardii typically reaches a maximum steady state in 3 days when taken orally. It does not multiply in the gut. Normally, it is not absorbed (4363).

Excretion: Less than 1% of the ingested dose is recovered from stools (4363).

General: Saccharomyces boulardii is typically a non-pathogenic yeast (4363).

Anti-amoebae activity: In vitro data suggests that Saccharomyces boulardii can reduce the number of red blood cells adhering to amoebae and decrease the number of amoebae bearing red blood cells (92815).

Anti-stress effects: Clinical research shows that taking Saccharomyces boulardii decreases salivary serotonin levels under conditions of psychological stress. However, although salivary levels of serotonin were associated with pulse rate, there was no association with anxiety, depression, or other markers of stress. Therefore, the clinical significance of this finding is unclear (107609).

Gastrointestinal effects: Saccharomyces boulardii is used as a probiotic agent to help colonize the gastrointestinal tract. It is used therapeutically in cases where disease is thought to occur due to depleted normal intestinal flora or colonization by pathogenic organisms (4363,18088). Some in vitro evidence shows that S. boulardii competes for attachment sites and blocks adherence of Clostridioides difficile, which helps prevent infection (72120,92813). S. boulardii is also thought to help for C. difficile infection by producing proteases that might decrease the toxicity of C. difficile toxins A and B (4348,4361,72187). Individuals who have low stool concentrations of S. boulardii after repeated use are most likely to have C. difficile recurrence (4360).

In addition to its effect on C. difficile, S. boulardii also shows evidence of interaction with cholera toxin (4363). In Crohn disease, S. boulardii increases secretory immune globulin A (IgA) in the intestine (7646). S. boulardii might cause an increase in the intestinal chloride resorption, which also may play a role in the treatment of Crohn disease (4362,7646).

Preliminary clinical research shows that taking S. boulardii along with miglustat might reduce miglustat-associated gastrointestinal disturbances in some people. Gastrointestinal disturbances caused by miglustat are thought to result from the inhibition of intestinal disaccharidases, particularly sucrase isomaltase. Inhibition of this enzyme leads to maldigestion of sucrose. S. boulardii is thought to help prevent this adverse effect by secreting sucrase, which can aid in the digestion of sucrose (95414).