Saccharomyces boulardii

Table of Contents

Other names

Probiotic Yeast
S. boulardii CNCM I-745
Non-Pathogenic Yeast

Synopsis

Saccharomyces boulardii is a non-pathogenic yeast strain that functions as a probiotic, meaning it supports the balance and health of the intestinal microbiota. Unlike most probiotics, which are bacterial (like Lactobacillus or Bifidobacterium), S. boulardii is a yeast, making it particularly useful in situations where antibiotics are being used, since it is resistant to antibiotic activity.

It is a subtype of Saccharomyces cerevisiae (baker’s yeast), but with distinct properties that make it suitable for medicinal use. S. boulardii is most commonly used to treat and prevent gastrointestinal disorders, especially diarrhea caused by antibiotics, infections (such as Clostridioides difficile), traveler’s diarrhea, and inflammatory bowel conditions like Crohn’s disease and ulcerative colitis. It works by inhibiting pathogen adhesion, producing antimicrobial compounds, neutralizing bacterial toxins, and modulating the immune response within the gut.

It has also demonstrated anti-inflammatory and barrier-protective effects in the intestinal lining, helping restore tight junctions between intestinal cells, which is especially valuable in leaky gut scenarios or post-infection recovery. Moreover, S. boulardii helps promote IgA secretion, bolstering mucosal immunity, and may reduce the recurrence of H. pylori infections when used adjunctively with antibiotics.

Available in capsule or sachet form, it is widely prescribed and recommended by both conventional and integrative medicine practitioners, often as a preventive measure during or after antibiotic use.

Historical Usage:
The discovery of Saccharomyces boulardii dates back to the 1920s, when French microbiologist Henri Boulard isolated the yeast from lychee and mangosteen skins in Indochina (modern-day Vietnam and Cambodia). He observed that local populations chewed the skins of these fruits during cholera outbreaks to control severe diarrhea. Recognizing the yeast’s therapeutic potential, Boulard isolated and cultured the organism, eventually leading to the development of the commercial probiotic now known as Saccharomyces boulardii.

It was not used in ancient herbal medicine or traditional systems like Ayurveda or TCM, since its identification and isolation required microbiological techniques unavailable until the 20th century. However, its practical origin—based on traditional practices involving tropical fruit peels—shows a clear intersection between folk observation and scientific validation.

By the 1980s and 1990s, S. boulardii gained traction in clinical research and began to be manufactured as a medicinal probiotic, especially in Europe, where it was marketed under names like Florastor. It quickly became a staple in gastroenterology, with controlled trials confirming its efficacy in both adults and children suffering from infectious diarrhea, antibiotic-associated diarrhea, and certain forms of colitis.

Today, it is one of the most well-researched and clinically validated probiotics, recommended not only for acute gastrointestinal infections but also for maintaining gut health, especially in immunocompromised or antibiotic-exposed patients.

Uses: Health Conditions

Antibiotics (side effects of) (Traditional)

Body Systems

Digestive System (Science)
Gastrointestinal Tract (Science)
Immune System (Science)
Intestinal System (Science)
Stomach (Science)