The term “microbiotic strain” refers to the most precise level of identification for a probiotic microorganism—more precise than the genus or species alone. It is the specific strain that determines a probiotic’s clinical indication, its gastric resistance, its interactions with the existing microbiota, and its scientific literature. Two probiotics of the same genus and species can have completely different effects depending on their strain. Explore our probiotic lineup.
How do you identify a probiotic strain?
The complete nomenclature of a probiotic consists of three levels—all three are essential for selecting a product backed by clinical data.
- Genus: Lactobacillus, Bifidobacterium, Saccharomyces —broad taxonomic category
- Species: rhamnosus, longum, boulardii —specifies the general properties of the species
- Strain (alphanumeric code): GG, 35624, NCIMB 30242, DSM 17938 — a unique identifier linked to the clinical studies conducted
- Complete example: Lactobacillus rhamnosus GG — “GG” is the strain code that refers to more than 1,000 specific clinical publications
- A product that lists only “Lactobacillus acidophilus” without a strain code cannot guarantee the effects reported in published studies
Key strains and their documented indications?
Each strain has its own indication profile—strains are not interchangeable.
- L. rhamnosus GG (LGG, ATCC 53103): acute diarrhea in children, post-antibiotic diarrhea, traveler’s diarrhea—the most extensively studied probiotic strain in the world
- L. reuteri DSM 17938: infant colic, regurgitation, pediatric constipation—the gold standard for neonatal care
- L. plantarum 299v: irritable bowel syndrome, bloating and gas, digestive comfort—several positive RCTs
- B. longum 35624 (Alflorex): IBS with an anxiety component, gut-brain axis—a well-documented psychobiotic strain
- Saccharomyces boulardii CNCM I-745: C. difficile diarrhea, post-antibiotic diarrhea, traveler’s diarrhea — antibiotic-resistant yeast
- L. acidophilus NCFM: lactose digestion, gut immunity, vaginal health—a well-documented, versatile strain
CFU and viability guarantee: how to read the labels?
CFU (Colony-Forming Units) are the key quantitative indicator—but how they are listed determines their actual value.
- "Through expiration date": CFU guaranteed until the expiration date—the most relevant indication
- “At time of manufacture”: CFU at the time of production—may have decreased by 90% by the expiration date depending on storage conditions
- Recommended dosages by indication: digestive health (1–5 billion), immunity (5–10 billion), post-antibiotic therapy (10–50 billion)
- Gastric resistance depends on the dosage form, not the number of CFU—HPMC or DRcaps capsules for acid-sensitive strains
- Storage temperature: check if refrigeration is required—some microencapsulated formulations are stable at room temperature
Strains and Allergies: What Preventive Measures Are Available?
Certain probiotic strains are being studied for their preventive role in allergic conditions—one of the most active areas of research.
- L. rhamnosus GG + B. lactis Bb12: documented reduction in the risk of atopic eczema in at-risk infants (meta-analyses)
- Maternal supplementation in late pregnancy + infant supplementation during the first 6 months: protocols studied for perinatal immune programming
- Psychobiotic strains (B. longum 35624, L. helveticus R0052): gut-brain axis and modulation of the enteric nervous system
- The strains influence immune tolerance by stimulating Tregs (regulatory T cells)—a common mechanism underlying anti-allergic effects
How should strains and prebiotics be combined?
The combination of strain(s) and prebiotic(s) forms a synbiotic —the most comprehensive supplementation strategy.
- Bifidobacterium + inulin/FOS: Bifidobacteria preferentially ferment inulin—a combination documented in synbiotic formulations—see inulin
- Lactobacillus + acacia fiber: gradual, well-tolerated fermentation; prebiotic effect without excessive gas
- S. boulardii: yeast not affected by prebiotics—can be freely combined with fiber
- The prebiotic nourishes the introduced bacteria and promotes their temporary colonization in the colon
- See our selection of prebiotics and lactic acid bacteria for a comprehensive supplement regimen
