Saccharomyces Boulardii Bacteria

Saccharomyces Boulardii: The Top 10 Benefits of this Probiotic Yeast

What is Saccharomyces Boulardii?

Saccharomyces boulardii refers to a species of tropical yeast found in fruits endemic to Southeast Asia, South America, and parts of the Southeastern United States. French biologist Henri Boulard first extracted the product from the lychee fruit, a tropical tree indigenous to the Fuangdong and Fuijan provinces of China, as well as numerous other countries in Southeast Asia and the Indian Subcontinent, in 1923. The lychee tree bears several small, roughly textured pinkish fruits, which have fleshy interiors. Though the exterior of the fruit is indigestible, its interior is known to be sweet and highly perfumed. Saccharomyces boulardii can also be isolated from the fruit of the mangosteen tree, which refers to a tropical evergreen tree indigenous to the Malaysian archipelago and the Maluku Islands of Indonesia (though these types of trees are also known to grow as far West as Puerto Rico and Florida).

The Best Saccharomyces boulardii on the Market!

Saccharomyces boulardii is known for behaving like a probiotic in the body, though it is characterized as yeast as opposed to live bacteria. Probiotics, which benefit the human digestive system by positively influencing the intestinal microbial balance, can be classified into two primary groups: lactobacillus and bifidobacterium. The first is the most common, and is easily accessible through yogurt products and other fermented foods. They are considered beneficial for gut health and can be utilized to alleviate diarrhea and other symptoms of gastrointestinal distress. The latter type is also found in dairy products and can be ingested to combat symptoms of Irritable Bowel Syndrome (IBS) and infectious diseases impacting the gut.

When ingested, the microorganism Saccharomyces boulardii passes through the human digestive system without binding to the mucosa, the innermost layer of the gastrointestinal wall. This is a particularly coveted characteristic in probiotics, as gastrointestinal distress is commonly caused by inflammation in the mucosal walls of the gut. Further, the digestive tract often impedes the bioavailability of many microorganisms that would function as effective probiotics if they were able to make it through the human digestive tract intact. This is not the case with Saccharomyces boulardii, which is resistant to stomach and bilic acids and immune to antibiotics. For this reason, the yeast microbe is often used in the treatment of antibiotic associated diarrhea (AAD). It has also been clinically proven to alleviate traveler’s diarrhea and Helicobacter pylori infection, and is believed to be effective in the treatment of Irritable Bowel Syndrome and Crohn’s Disease.

Saccharomyces Boulardii Benefits and Uses


Candida, or Candida albicans, refers to a type of opportunistic pathogenic yeast that is naturally occurring in the human body. Typically, the fungus Candida exists in miniscule amounts on the skin and nails, within the mouth, and in the human gut flora without issue. However, when health and environmental factors are conducive, Candida can spread and proliferate, causing a fungal infection called candidiasis. This infection is typical in immunocompromised patients, and is characterized by digestive issues, chronic fatigue or fibromyalgia, skin and nail fungal infections, difficulty concentrating or lack of focus, eczema, psoriasis, and/or rashes, and genital or urinary tract infections. Fortunately, candidiasis is easily treated with the appropriate medications.

Research has indicated that Saccharomyces boulardii is likely effective in the treatment and alleviation of candidiasis symptoms. In a study published by the Annales de Microbiologie  in 1982, researchers examined the impact of Saccharomyces boulardii in the digestive tracts of mice harboring complex flora of human origin. They observed an antagonistic effect exerted by S. boulardii on various strains of candida (effective against Candida albicans, C. krusei, and C. pseudotropicalis, but ineffective against C. tropicalis). Later in 1993, researchers at the University of Chicago came upon similar results. They found that S. boulardii decreased C. albicans translocation to the mensenteric lymph node, liver, spleen, and kidneys in immunosupressed mice. Finally, in 2007, researchers found that S. boulardii significantly decreased intestinal colonization of C. albicans in mice suffering from colitis.

The Best Saccharomyces boulardii on the Market!

Weight Loss

It has long been suspected that the bacteria in the human gut impacts body weight, and that improvement in the digestion and efficient absorption of nutrients is beneficial towards weight management. As the worldwide prevalence of obesity has more than doubled since 1980, many researchers have turned to probiotics in the prevention and treatment of obesity. However, it was not until 2014 that researchers at the Université Catholique de Louvain in Brussels, Belgium examined the antiobesity properties probiotic yeasts. Specifically, they found that S. boulardii reduced body weight and fat mass in overweight and type 2 diabetic mice, and altered gut microbiota composition by decreasing negative phyla Firmicutes, Proteobacteria, and Tenericutes. Though research specifically addressing S. boulardii and its ability to regulate body weight and aid in fat loss is relatively limited and recent, findings recommend further investigation.

Small Intestinal bacterial overgrowth (SIBO)

Small intestinal bacterial overgrowth (SIBO) refers to a condition in which a dangerous amount of bacteria proliferates within the small intestine. This syndrome is common in intestinal failure, and can contribute to gastrointestinal-mucosal injury and malnutrition. In the worst cases, the translocation of bacteria across the intestinal epithelium can contribute to systematic sepsis. Therefore it is very important to treat the condition itself as well as the nutritional deficiencies that arise as a result of SIBO. Research indicates that Saccharomyces boulardii supplementation may be effective in the treatment of SIBO. In a study conducted by the Hôpital Lariboisère Saint Lazare in Clichy, France, patients with bacterial overgrowth-related diarrhea underwent antibiotic treatment as well as S. boulardii treatment (1500 mg/day for seven days). Results yielded that S. boulardii (as well as norfloxacin and amoxiclllin-clauvanic acid) was effective in the treatment of SIBO-related diarrhea. This 1999 study is arguably the most frequently cited in discussions regarding S. boulardii’s potential role in SIBO treatment. The microorganism’s known capacity to regulate intestinal gut flora and the aforementioned research recommend further investigation in S. boulardii’s ability to alleviate SIBO and its symptoms.


Research related to S. boulardii’s ability to treat and alleviate chronic acne is very limited. However, advocates of S. boulardii often cite acne treatment as one of its many beneficial actions, based primarily on the relationship between intestinal microflora and systematic inflammation of the skin. For example, in a study published by the journal of Applied Microbiology and Biotechnology, researchers found that various probiotics markedly suppressed overgrowth of Propionibacterium acnes, a commensal skin bacterium that contributes to acne vulgaris, in mice. This and similar research indicates the validity of the “gut-brain-skin axis,” or the hypothesis that emotional states, intestinal microbiota, and skin inflammation systematically and cyclically impact one another. However, more research related to S. boulardii in acne treatment specifically is needed to validate this theory.


There is an abundance of research indicating S. boulardii’s effectiveness in treating various kinds of diarrhea, from traveler’s to antibiotic-associated to acute diarrhea in children. In 1989, researchers at the University of Washington in Seattle conducted a double-blind, placebo-controlled study addressing S. boulardii and its effectiveness in treating antibiotic-associated diarrhea. They found that, of 180 patients, the 22% receiving placebo experienced diarrhea compared with the 9.5% of patients receiving S. boulardii. Later, in 2005, researchers at the University of Warsaw conducted a similar study with a total of 269 children (aged 6 months to 14 years) being treated for otitis media and/or respiratory tract infections. Results indicated that patients receiving S. boulardii had a significantly lower prevalence of antibiotic-associated diarrhea when compared with placebo, with no adverse effects observed. In 1993, a study published with the Austrian medical journal Fortschritte der Medizin , indicated that S. boulardii showed “promising results” in a double-blind, placebo-controlled study of 3,000 Austrians traveling to distant regions. Researchers noted a significant reduction in the incidence of traveler’s diarrhea among patients, particularly among those traveling to North Africa and the Near East.

Blastocystis Hominis

Blastocystis hominis refers to a microorganism found in the human digestive tract that has caused some controversy in terms of its classification – researchers have argued for its status as a yeast, fungus, and ameboid, flagellated, or sporozoan protozoa. Though the microorganism is still being evaluated, researchers suspect that its proliferation can cause an infection characterized by diarrhea, nausea, abdominal cramps, loss of appetite, hives, and/or fatigue. Some Blastocystis hominis infections can actually be asymptomatic and clear up on their own, but for persistent symptomatic infections, evidence indicates that Saccharomyces boulardii may be effective in treatment. A randomized, placebo-controlled study published by the journal of Parasitology Research examined S. boulardii’s efficacy in treating children with symptomatic Blastocystis hominis infections. Results indicated that both the antibiotic metronidazole and S. boulardii have potential beneficial effects in alleviating Blastocystis hominis-related diarrhea. However, more research is needed to confirm both S. boulardii’s efficacy in B. hominis treatment and B hominis’s mechanism of action in the human digestive system.

Clostridium Difficile

Clostridium difficile (or C. diff) refers to a potentially fatal bacterial infection that can cause severe inflammation of the colon, also known as colitis. C. diff bacteria typically lives in small quantities in the human intestines without causing any issue, but it can be very dangerous if it proliferates. This kind of infection is often spread in health care facilities, and it can actually be caused by antibiotic use, specifically when an antibiotic kills too many healthy bacteria. There has been some research conducted addressing S. boulardii’s complementary role in the treatment of this illness. In a double-blind, randomized, placebo-controlled trial study published by the Journal of the American Medical Association in 1994, researchers examined a combination treatment of S. boulardii alongside standard antibiotics in the treatment of adults hospitalized from C. diff infections. Results indicated that the efficacy of S. boulardii in combination with antibiotic supplementation was significant in comparison to placebo. Further, there were no serious adverse reactions associated with S. boulardii. A very similar study was conducted again in 2000 (published by the Journal of Clinical Infectious Diseases). Findings indicated that a combination treatment of vancomycin and S. boulardii was highly effective in the treatment of C. diff infections in immunosuppressed adults.

Crohn’s Disease

Crohn’s disease refers to a condition that causes inflammation of the digestive tract, which can lead to chronic diarrhea, chronic fatigue, malnutrition, and severe abdominal pain. To date there is no cure for the disease, but there are numerous therapies and medical treatments that can bring about long-term remission and aid increased functionality in affected patients. In a study published by the journal of Digestive Diseases and Sciences, thirty-two patients with Crohn’s disease in clinical remission were treated with mesalamine three times a day or mesalamine two times a day with a preparation of S. boulardii once daily. Researchers found that clinical relapses occurred in 37.5% of patients receiving the mesalamine thrice daily, and 6.25% in patients treated with both mesalamine and S. boulardii. However, in a later study conducted among various hospital research groups in France performed a similar study in which Crohn’s patients in remission received S. boulardii once per day or placebo for fifty-two weeks. 38 patients in the S. boulardii group relapsed in comparison to 42 in the placebo group, which was classified as an insignificant difference. Based on these and similar data it can be hypothesized that, while Saccharomyces boulardii is not able to prevent relapse in Crohn’s patients, it may be effective as a non-primary treatment alongside antibiotics.

Ulcerative Colitis

Ulcerative colitis refers to a condition that causes inflammation and ulcerative sores in the lining of the large intestine. Typically, the lower colon and rectum are most significantly impacted in incidences of ulcerative colitis, but in severe cases the entire large intestine can be affected. Symptoms include abdominal pain, cramping, diarrhea, and rectal bleeding. As Saccharomyces boulardii is well known for its effectiveness in diarrheal diseases, there has been some research dedicated to the microorganism’s ability to treat symptoms of ulcerative colitis. In a 2003 pilot study published by the European Journal of Gastroenterology and Hepatology, researchers evaluated patients with ulcerative colitis receiving 250 mg of S. boulardii three times a day for four weeks. Of the twenty-four patients who completed the study, seventeen attained clinical remission, and the researchers confirmed that further controlled studies were warranted to confirm S. boulardii’s efficacy.

IBS (Irritable Bowel Syndrome)

Irritable bowel syndrome (IBS) is a relatively common illness that affects the large intestine, characterized by abdominal pain, diarrhea and/or constipation, bloating, excessive gas, and abdominal pain. Though the exact cause of IBS is unknown, researchers have verified that the condition can be managed via lifestyle and dietary regimentation, as well as various medications and/or supplementation. In a study conducted by researchers at Chung-Ang University College of Medicine, Yonsei University College of Medicine, and University of Ulsan College of Medicine in Seoul, South Korea, researchers examined the effects of Saccharomyces boulardii on quality of life (QOL) and symptoms in patients with diarrhea-predominant Irritable Bowel Syndrome. Findings indixated that all eight domains of the IBS-QOL framework were significantly improved in the S. boulardii group. However, researchers noted that bowel frequency and stool consistency was not significantly different between the S. boulardii and placebo groups. In a study conducted at the Agha Khan University Hospital in Karachi, Pakistan, researchers examined more closely the mechanisms of action of the probiotic S. boulardii on inflammatory cytokines in patients with diarrhea-dominant IBS. Again, researchers found that, though blood and tissue levels of proinflammatory cytokines did not vary significantly between the S. boulardii and placebo groups, overall QOL improvement was more marked in the S. boulardii group. Evidence points to S. boulardii as playing a productive role in overall health-related IBS-QOL, though its impact on the frequency and quality of bowel symptoms may be limited.

Freeze Dried (Lyo) vs Heat Dried: Which is Better?

Saccharomyces boulardii can be isolated in two ways: heat-drying and lyophilization. Lyophilization refers to the freeze-drying of bacterial cultures, and is particularly efficient in preserving biological material. Many microorganisms, including Saccharomyces boulardii, easily survive the freeze-drying process and are efficiently rehydrated after extended periods in storage. Conversely, heat-dried biological material loses its potency much more rapidly and is unstable at room temperature.

Saccharomyces Boulardii Dosage

In adults, an appropriate dosage of Saccharomyces boulardii is typically 5 billion CFU/g once or twice daily on an empty stomach, taken with a glass of water. It’s important to note you cannot dose by the size of the capsule because different brands have different bacteria per gram. It is essential you read the supplement facts and dose by bacteria.

Saccharomyces Boulardii Side Effects, Safety, Dangers, Contraindications and Warnings

Saccharomyces boulardii is generally associated with very minimal side effects. The most commonly reported side effects in healthy adults include constipation, flatulence, increased thirst, and bloating. However, this supplement is not considered safe for individuals who are using intravascular catheters.

In individuals with weakened immune systems and in pregnant women, cases of fungemia (the presence of yeast in the bloodstream) have been reported. Please consult your physician before starting a supplement regime if S. boulardii. Further, individuals allergic to yeast could suffer a dangerous reaction to S. boulardii supplementation.

Constipation: In general, Saccharomyces boulardii is well-tolerated in the human body and effective in the treatment of various diarrheal disorders. However, in human studies some individuals have reported constipation as a side effect of taking the supplement (as well as bloating and increased thirst). Clinical evidence points to S. boulardii as effective in the treatment of acute diarrhea and gastrointestinal infections, as opposed to alleviating constipation. In sensitive individuals, S. boulardii may actually cause constipation.

Warning: If you have a vascular catheter do not consume Saccharomyces boulardii. It is suggested there might be some sort of contamination of the air, hands or environment that has led to extremely rare cases of fungemia.

Frequently Asked Questions (FAQ)

Can Saccharomyces boulardii cause yeast infections?

Saccharomyces boulardii has been demonstrated to be beneficial in the treatment of Candida albicans (also a type of yeast) infections. Given its yeast-against-yeast capabilities, it has been hypothesized that S.boulardii might be efficacious in the treatment of other types of yeast infections. However, research into the microorganism’s protective capacities against types of yeast infections other than candidiasis is very limited. In rare cases, there have been reported incidences of fungemia (inappropriate amounts of yeast in the bloodstream) in immunocompromised patients and in patients with intravenous catheters who were taking S. boulardii supplements. Here is more reading if you’re looking for more information on probitiocs specific to yeast infections.

Can Babies or Infants take Saccharomyces boulardii?

There have been some clinical studies examining S. boulardii’s efficacy in treating infants and children with acute diarrhea. In a research study conducted at the Universidade Federal de Minas Gerais in Minas Gerais, Brazil, 186 infants (from 6 to 48 months old) hospitalized for acute diarrhea were treated with S. boulardii. Of the 176 infants who completed the trial, the 90 treated with the supplement showed a significant reduction in diarrhea duration in comparison to the placebo group with no adverse side effects. However, parents should exercise caution and consult with a physician before administering any type of probiotic to an infant or a child.

Can you take Saccharomyces boulardii with other probiotics?

Saccharomyces boulardii has no known specific contraindications with other probiotics. However, an excess of probiotic supplementation can cause diarrhea or constipation, flatulence, bloating, abdominal pain, rashes and skin inflammation, and acne outbreaks. Therefore it is inadvisable to “megadose” with numerous probiotics at once.

Can Saccharomyces boulardii cause diarrhea?

Saccharomyces boulardii is known to be effective in the treatment and prevention of diarrheal illnesses. It is very unlikely to cause diarrhea; on the contrary, in sensitive individuals it may cause constipation.

How to take Saccharomyces boulardii:

Saccharomyces boulardii is available in capsule or powder form. To ingest S. boulardii as a powder, individuals will typically blend a packet’s worth into at least four ounces of water, juice, or milk, or into a serving of yogurt or applesauce. It is inadvisable to mix probiotic powder or capsules with hot or acidic foods or beverages. S. boulardii should be stored at room temperature, protected from excess moisture or heat.

Is Saccharomyces boulardii a probiotic?

Yes, Saccharomyces boulardii is considered a probiotic. This is because its activity in the human digestive system resembles the protective effects of healthy gut flora. However, instead of being a bacterial probiotic, S. boulardii is a probiotic yeast.

Does Saccharomyces boulardii need to be refrigerated?

No, in fact the highest quality products  (freeze dried or lyo) recommend you do not refrigerate them as they are already stable. If a product does suggest refrigeration it’s a good indicator that it is a heat dried Saccharomyces boulardii and is of the lowest quality.

Does Saccharomyces boulardii lose bacteria over time?

Yes, over time the bacteria in Saccharomyces boulardii does die. However; it only loses about 15% of its bacteria a year, which is considerably less than other probiotics that lose 50% a year. Some manufacturers put a higher amount of bacteria in their product in order to make up for this gradual die off of bacteria.

Should I take a Prebiotic with Saccharomyces boulardii?

Personally I’d recommend you don’t take Saccharomyces boulardii with a prebiotic. There is virtually no evidence to suggest a prebiotic is needed with Saccharomyces boulardii. What is interesting though, is that Saccharomyces boulardii on it’s own might have prebiotic characteristics, so it might not hurt.


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