Just as Lactobacillus GG is the most-studied bacterial immunobiotic in the world, Saccharmoyces boulardii (S. boulardii) is the best researched probiotic yeast, with nearly 300 peer-reviewed studies. Isolated from litchi fruit in the 1920’s, S. boulardii colonizes the gut within three days of oral consumption and disappears from stool within 5 days after discontinuation. New research confirms it as a first choice for preventing and treating traveler’s diarrhea, antibiotic - associated diarrhea, and C. difficile colitis, as well as helping improve Crohn’s disease, ulcerative colitis and irritable bowel syndrome.

Studies have shown that S. boulardii:

• Protects against gut pathogens
• Modulates the immune response
• Decreases inflammation in a wide range of disorders
• Inhibits bacterial toxins
• Enhances the gut’s natural enzymes and nutrient transporters
• Increases the most important gut immunoglobulin, Secretory IgA

Hello Good Yeast, Goodbye Diarrhea

It’s widely known that S. boulardii helps prevent and treat antibiotic-associated diarrhea (AAD) caused by pathogens such as Clostridium species, Staphylococcus aureus, Klebsiella, Candida and Salmonella. Mainstream as well as integrative medicine doctors often prescribe it along with antibiotics. “Given the broad range of protective effects in multiple gastrointestinal disorders,” write researchers from Harvard Medical School in a 2006 study, “we hypothesize that S. boulardii modulates host signaling pathways involved in intestinal inflammatory responses.” Indeed, the researchers found that S. boulardii blocks activation of inflammatory molecules called kinases. In another study, Harvard researchers found that the yeast blocked activation of other key inflammatory molecules like NF-Kappa B.

Other new research confirms the yeast’s potency in preventing diarrhea. S. boulardii slashed the risk of antibiotic-associated diarrhea by nearly 2/3 in a study of 269 children with ear or upper respiratory tract infections. The children were given antibiotics plus 250 milligrams of S. boulardii twice daily or a placebo. Only 8% of S. boulardii children had diarrhea, compared to 23% taking a placebo. In another study on 151 hospitalized patients, only 1.4% of those who were given S. boulardii in addition to antibiotics had diarrhea, compared to 9% on placebo. In addition C. difficile toxin was found in 2 of the placebo patients and none of the S. boulardii patients.

In fact, S. boulardii protects against the devastating C. difficile colitis. When 124 patients on high dose vancomycin for C. difficile colitis were given S. boulardii, rates of recurrence plummeted from 50% to 16.7%. A 2006 meta-analysis found that various probiotics help prevent antibiotic-associated diarrhea, but only S. boulardii prevents and treats C. difficile associated diarrhea.

S. boulardii is effective in preventing traveler’s diarrhea as well, of which 80% is caused by E. coli, Shigella or Salmonella species. A study of over 1000 travelers found that rates of diarrhea dropped from nearly 40% to 29% when travelers started taking S. boulardii at 1000 milligrams daily, five days before and for the duration of their trip.

Diarrhea in children, in patients on enteral feeding tubes, and in AIDS patients, also responds to S. boulardii. Even Crohn’s patients may benefit from S. boulardii, according to a 2008 study of 34 patients treated with either the probiotic yeast or a placebo. Those receiving S. boulardii experienced significant improvements in intestinal permeability. Other animal studies have shown that S. boulardii helps maintain the gut’s epithelial integrity and ameliorate inflammatory responses in the presence of various infecting pathogens.

Secretory IgA: The Critical Mucosal Immunoglobulin

Secretory IgA (SIgA) is our first line of defense against invading microbes and is key to maintaining mucosal homeostasis and integrity. It is the main immunoglobulin found in mucus, tears, saliva, vaginal fluid, and secretions from the intestine and lining of the lungs. It resists degradation by enzymes, and provides profound protection against pathogens.

S. boulardii is uniquely able to stimulate SIgA. A June 2009 study compared Bifidobacterium animalis, Escherichia coli, Lactobacillus casei and Saccharomyces boulardii. The study found that S. boulardii stimulated significantly higher levels of secretory IgA than the other organisms, and S. boulardii alone induced a higher level of the potent anti-inflammatory cytokine, Interleukin 10 (IL-10). S. boulardii can increase SIgA by as much as 56% in duodenal fluid, according to an animal study from the University of Louvain in Brussels. SIgA nearly doubles when mice are fed S.b. and then exposed to C. difficile toxin. In germ-free mice, inoculation with S. boulardii increased total IgA.

S. boulardii is anti-inflammatory: it decreases the expression of inflammatory cytokines including interleukin 8 (Il-8), IL-6, IL-1b, tumor necrosis factor alpha (TNF-a) and interferon gamma (IFN-y). It may even decrease the number of T-cells producing IFN-y. S. boulardii can decrease IL-8 secretion from human colon cells after stimulation with a toxin from C. difficile. It can also reduce inflammation by suppressing nuclear factor-kappa b (NF-kB), which is activated during infection. In one study of human colon cells, S. boulardiiinhibited NF-kB pathways after cells were exposed to a strain of E. coli that causes hemorrhage. Recent research shows that S. boulardii actually produces a specific low-molecular weight factor that directly blocks NF-kB activation.

S. boulardii also helps reduce levels of nitric oxide, which is associated with inflammatory bowel disease. It neutralizes bacterial toxins and inhibits toxin-binding to intestinal receptors as well as bacterial adhesion. In this way S. boulardii increases the gut’s integrity and helps protect it. It even increases the activity of enzymes like lactase and sucrase-isomaltase, helping aid digestion and absorption of nutrients from foods.

In a word, Saccharomyces boulardii restores intestinal homeostasis.

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