Probiotics are made of microorganisms like yeast or bacteria and they promote overall health by improving digestion. Saccharomyces boulardii, also referred to as S. boulardii and pronounced SAK-a-roe-MYE-sees-boo-LAR-dee, is a yeast found naturally in tropical plants.
What is Saccharomyces Boulardii?
Saccharomyces boulardii is sometimes used as a probiotic, and can be found in probiotic supplements, with the purpose of improving the overall health of the human intestinal tract. It also serves to provide protection to the intestinal walls by adhering to them, and blocking out harmful bacteria. Particularly proven to be found effective is S. boulardii.
Studies have shown that saccharomyces boulardii has probiotic properties and that “recent data has opened the door for new therapeutic uses of this yeast as an ‘immunobiotic'”, which are microbes that promote immune system health from within the gut, improving overall health of the body.
Saccharomyces Boulardii was originally discovered in 1923 by French microbiologist Henri Boulard. Boulard was working in Indochina when he observed that locals would consume tea made with the tropical fruits lychee and mangostein to ward off diarrhea caused by disease and illness. Boulard was able to isolate the yeast strain saccharomyces from these fruits and named the strain of probiotic after himself, saccharomyces boulardii, or S. boulardii.
Following the discovery of S. boulardii, European scientists went to work studying its properties and found compelling evidence that it could be useful in combating pathogenic organisms. A plethora of studies are still being carried out to this day on saccharomyces boulardii and its health effects. There is still much to learn about this probiotic but there’s no denying the ample evidence of its health benefits and very minimal side effects.
Where is it Found?
Saccharomyces boulardii is a strain of Saccharomyces cerevisiae(Bakers yeast). Saccharomyces boulardii can be found in supplements, sauerkraut, kimchi, sour pickles, kombucha, sour dough bread, yogurt, and more. You can also find it in supplement drinks.
Saccharomyces Boulardii Medical Effects On The Human Body
Treatment of Antibiotic-Associated Diarrhea
Various studies have found saccharomyces boulardii to be effective in the treatment of diarrhea. Out of an analysis of 21 randomized trials and testings of controlled substances and almost 4800 participants confirmed saccharomyces boulardii is effective for reducing the risk of diarrhea.
- A randomized controlled trial conducted by The Medical University of Warsaw found that patients who took saccharomyces boulardii orally had a lower prevalence of diarrhea during and up to two weeks after treatment. The researchers concluded that saccharomyces boulardii “effectively reduces the risk of antibiotic‐associated diarrhoea in children.”
- A systematic review and meta-analysis on saccharomyces boulardii in adult patients found evidence that saccharomyces boulardii reduced the side effects of H. pylori treatment and prevented enteral nutrition-related diarrhea. This study also found that it is “significantly effective” for treating adult acute diarrhea and traveler’s diarrhea. 
Treatment of Diarrhea Related to Illnesses
There have been several studies that show Saccharomyces boulardii may be helpful in treating diarrhea caused by other illnesses such as:
- HIV/AIDS: on average most patients gained weight while being on Saccharomyces boulardii, during an 18 month trial. There was no adverse reactions reported in these individuals with a compromised immune system.
- Clostridium difficile infection: studies show people a reduction in relapse
- Acute gastroenteritis: based on a paper that was published by ESPGHAN working groups, which was based on several test may produce positive results in re-hydration therapy.
- Helicobacter pylori infection: studies have shown it to reduce the side effects of H. Pylori which include diarrhea and nausea.
- Traveler’s diarrhea: anytime a person travels they may experience an upset stomach and diarrhea. This yeast may help in reduction of symptoms.
- Crohn’s Disease
- Ulcerative Colitis
- B-lactam associated diarrhea
- C-diff infections[8–12]
- HIV-related diarrhea
- Other Gastrointestinal Disorders
Maintenance Treatment of Disease
For therapeutic treatment of clostridium difficile: in a randomized placebo-controlled trial, researchers found that saccharomyces boulardii was “shown to be an effective and safe therapy for these patients with recurrent CDD(c. difficile)”.
Another study done on rats found that saccharomyces boulardii “may reduce some of the enterotoxic effects of toxin A by inhibiting toxin A-receptor binding.”
Maintenance treatment of Crohn’s disease: a study on patients with Crohn’s disease discovered preliminary data showing that saccharomyces boulardii could be effective in the maintenance treatment of the disease.
Top 4 killers of Saccharomyces Boulardii
- Probiotics need to be protected in enteric-coated capsules for them to be able to reach and populate the lower intestine. 
- Tap Water: unfortunately, tap water isn’t great for yeast growth. It can reduce, slow or possibly stop growth altogether.
- Hot or cold temperatures: yeast grows best in warm to very warm temperatures. Although it can survive a wide range of temperatures, it begins to suffer injury at temperatures of 120 degrees Fahrenheit and will likely lose all life by 140 degrees Fahrenheit. Freezing will put the yeast in a state of suspension.
- Starvation: Yeast needs both food and salt to grow. Its food is a probiotic. Just like anything if you have too much or not enough of something it can cause havoc on your system.
How Safe is it?
Saccharomyces boulardii has been found to have very minimal risk. Saccharomyces boulardii is likely safe for adults to take orally. In rare cases in subjects with weakened immune systems or in pregnant women it may cause fungal infections that can spread through the body, as well as into the bloodstream. If for whatever reason you have a weakened immune system, or for women who are pregnant/breastfeeding, precaution should be taken and you should consult with your physician before taking probiotics, as the side effects in these individuals are not fully known yet.
Saccharomyces boulardii is safe for use in otherwise healthy people. As with any medications or concerns consult with a physician.
Who Should Avoid Use of Saccharomyces Boulardii?
People with yeast allergies: people with yeast allergies should avoid use of saccharomyces boulardii unless advised otherwise by a physician. Saccharomyces boulardii can cause allergic reactions in these individuals.
People suffering from weakened immune systems: fungemia is an infection that occurs when a yeast infection spreads to the blood stream. People who are taking medications that negatively compromise the immune system or have a weakened immune system due to illness or disease should avoid taking saccharomyces boulardii as there have been reported cases of fungemia related to its use.
How to Pick the Best Saccharomyces Boulardii Supplements
- In order to reap the health benefits of saccharomyces boulardii, the supplement should have a minimum effective dose of 1 billion CFU.
- For preservation, supplements containing saccharomyces boulardii should be freeze dried. In order to ensure that they have the opportunity to populate the lower intestine, be sure the capsules are enteric coated.
- In this study researchers found that “alginate microspheres(i.e. microencapsulation) could be of great interest in therapeutic applications of the yeast.” In other words, it’s a good idea to ensure that whatever saccharomyces boulardii supplements you decide to buy are microencapsulated so that the supplement is bioavailable(meaning it lasts through to the intestinal tract and has its intended therapeutic effect) upon consumption.
- For the best results we recommend looking into a blend of probiotics that include saccharomyces boulardii, along with at least 10 strains of healthy probiotic bacteria.
- As with all supplements, it should be non-GMO, free from unnecessary fillers and binders, and made in a cGMP certified facility in the USA.
- Probiotic supplements should be purchased from company you’ve researched and trust. Legitimate probiotic supplement vendors have simple, straight forward return policies.
- Any high-quality supplements will be be made in a cGMP certified facility so you know they’ve been grown in sanitary conditions.
How to get the most out of your supplements
- Choose your supplements from a reputable company.
- Follow the directions on the label and take the recommended dosage.
- Avoid taking probiotics on an empty stomach.
- Store probiotics properly – in most cases that means in a cool, dry place.
- Probiotics work best when taken in addition to a healthy diet. Probiotics are able to flourish best when they’re combined with fruits, vegetables and foods rich in fiber.
Want to Learn More?
Here are some more helpful resources on saccharomyces boulardii: