What Is It Really?

Saccharomyces boulardii (SB) is a live yeast packaged in capsules and sold over the counter in Europe to treat diarrhea. Studies suggest that SB protects the gut from amebas and cholera, may keep candida from spreading, alleviates diarrhea caused by c. difficile, Crohn's disease and diarrhea of unknown cause in PWAs, and traveller's diarrhea.

How's It Work?

We don't know. Test tube results show it doesn't directly kill the bugs (bacteria, fungi, or parasites) causing infection. Theories of how it works include: 1) SB or something it produces may prevent gut inflammation that causes diarrhea, by interfering with how various bugs bind to gut cells; 2) SB might increase certain protective immune proteins that in turn kill the infection-causing bugs; and/or 3) SB might be a superior non-toxic competitor with amebas and candida in the intestine ("There ain't room in this gut for the both of us.").

Clinical Studies in PWAs

There's only been one so far, as one in Seattle was cancelled. In a French study, 30 PWAs with chronic, severe (watery, 4-8 liters/day) diarrhea from no known cause, all with a history of CMV, MAI and KS, took 3 grams (3000 mg) of SB per day. Within two days, the volume of their diarrhea had been reduced to 1 liter. By the eighth day on SB, their stools were normally formed.

SB for C. Diff Diarrhea

Taking antibiotics can cause diarrhea by killing off little organisms you need to maintain a healthy digestive system. Then other naturally occurring bacteria and yeast may rage out of control 97 without their natural predators to keep them in check. C. diff is one of the most difficult of these antibiotic-caused diarrheas to treat, mostly because it's so resistant to most other antibiotics. It's usually treated with vancomycin - a fairly toxic drug, that often fails, with recurrence of severe diarrhea. Several studies of SB have been conducted in people with antibiotic diarrheas. In one, 13 people with recurrent C. diff tried a regimen of thirty days SB plus 10 days of vancomycin - 11 were cured with no recurrence of C. diff. A placebo controlled study of 180 people on various antibiotics reported that 22% of the people on placebo got diarrhea, but only 9.5% on SB did. A study of SB for infants with C. diff reported dramatic results as well.

Studies for Other Diarrheas

The largest placebo controlled study of SB was in 3000 Austrians who took 250 or 1000mg while they travelled abroad. People on SB got significantly fewer cases of diarrhea than those on placebo, and there were less cases on high dose than low dose. Another study evaluated SB in 20 patients with Crohn's disease, a life-long syndrome where people suffer from severe diarrhea, gut pain and weight loss. They were all treated with SB (250 mg 2x/day) for two weeks. All had fewer bowel movements. Half stayed on SB, while the others were put on placebo for another ten weeks. Those on SB had reductions in bowel movements while the group on placebo went back to the same number of bowel movements that they had had when the study began.

Side Effects and Toxicity

Few side effects have been reported from the use of SB. People with yeast allergies should not take SB, and some people have complained of itchiness and facial swelling (sounds like...yeast allergy). Because this product is composed of live yeast, you must not drink alcohol for it to be effective. Alcohol will kill the yeast. It is important to drink a lot of other liquids when you have a case of diarrhea to avoid dehydration. SB is a different yeast than candida, which causes oral and vaginal thrush. SB does not increase thrush and in fact may lessen or prevent thrush infections. Some are concerned that since this is a living organism it may take root in an immune-compromised person and cause systemic infections. A number of people with AIDS have been on SB for more than a few years without any reported complications. But there have been three reported cases of systemic SB fungal infections. In two cases, patients had perforated colons after surgery, which allowed the yeast to escape their GI tracts. Both responded quickly to a course of Ampho B. A very ill one year old girl treated with SB and 6 antibiotics for pneumonia, diarrhea, and fever developed an SB fungal infection. She was treated successfully with Fluconazole and improved overall with the use of aspirin. We must remember that she is an infant, and her system is substantially different than an adults. Normally, the yeast doesn't get absorbed; it moves right through the GI tract and is excreted in the stool in 3 to 5 days. Contact your doctor if you have any conditions that may cause a rupture in your GI tract (CMV, KS, MAC, ulcer) and you are taking SB.

Drug Interactions

Good News: If you take SB with certain antibiotics, namely clindamycin and amoxicillin, the level of SB in your gut is substantially increased. These antibiotics kill off other organisms that may eliminate the yeast, so elevated levels of SB when taking these antibiotics are good. These drugs can cause C. diff, which SB may keep in check. Bad News: Antifungals can kill SB, just like they kill candida and other fungal infections. Fortunately, fluconazole's effect on SB is minimal, and PWAs who want to try SB can continue to prophylax with a dose of 50-100 mg a day. Even so, for optimal effect, you should not take fluconazole and SB at the same time of the day.


The dose of SB differs depending upon the condition you are using it for, but ranges from 250 - 1000 mg a day. In PWAs with severe diarrhea of unknown cause, the starting dose is at least three times as much - 3000 mg a day. You may not need to continue at this dose - if it gets your diarrhea under control, you can gradually lower your dose till you find the lowest dose that works for you. In the Seattle study, if the SB works after two weeks, the people reduce their dose to 2000 mg a day. If it still works, after two more weeks, the dose is lowered another 1000 mg. This continues until each person finds his or her lowest effective maintenance dose.

On-going Studies

At present, the one American trial for PWAs is closed, because of a company decision to focus on a phase III c. difficile trial, for which any immunocompromised patients are excluded. Most unhelpful and mean. For more information about the study, call Kris Moyer, RN, at (206) 322-5663.

Pharmaceutical vs. Health Food SB

There are a few different European pharmaceutical products. In the US, Jarrow, a health food company, makes it. Jarrow's product is less expensive, but may come with lower concentrations of live yeast. How good is the Jarrow yeast? We don't know. It may well be fine. Biocodex, the company with the US license, which clearly has a big financial reason to be biased, claims that they analyzed Jarrow's SB, and that: 1) it suffers from poor quality control; 2) the SB viability was not preserved by the packaging and manufacturing process, so there was a very decreased shelf-life; and, 3) there were nowhere near as many organisms per capsule as Jarrow claimed. Jarrow claims this isn't so, and that their analyses show their product's quality to be fine. Biocodex's results:

  • Jarrow: 500 million yeast per 310 mg capsule
  • Biocodex and Thiemann: 1 billion yeast per 250 mg capsule

What We Carry

The Health Group currently carries Thiemann, a Biocodex brand of SB - but it is expensive. At 3000 mg/day, a four day supply costs $33. Jarrow's brand is available from Healing Alternatives (San Francisco, CA) and DAAIR (NYC).