Probiotic Strains Explained
Probiotic effects are strain-specific: results for one strain do not carry over to another, even within the same species.[NIH Office of Dietary Supplements] That is why we score strains and strain-defined products rather than "probiotics" as a whole.
| Strain or type | Score | Owner comments | Unwanted effects |
|---|---|---|---|
| B. longum 35624 (Align) | 3.4 | 77 | 11% |
| L. rhamnosus GG (Culturelle) | 3.9 | 53 | 5% |
| Saccharomyces boulardii | 4.0 | 478 | 8% |
| L. plantarum 299v | 3.6 | 4 | 0% |
| High-potency multi-strain (VSL#3 / Visbiome) | 3.7 | 70 | 16% |
| Spore-based probiotics (Bacillus) | 4.2 | 194 | 8% |
| L. reuteri | 3.5 | 278 | 9% |
| Akkermansia (Pendulum) | 3.3 | 124 | 16% |
| Seed DS-01 | 3.7 | 45 | 19% |
Bacteria vs yeast
S. boulardii is a yeast, so antibacterial antibiotics do not affect it the way they affect bacterial strains.[PubMed] A 2018 network meta-analysis compared probiotics for antibiotic-associated diarrhea.[PubMed]
What the evidence looks like
A 2023 systematic review in Gastroenterology pooled probiotic trials in IBS and found some strains or combinations may be beneficial, but the certainty of the evidence was low to very low.[PubMed]
The NIH notes probiotics may not be safe for people who are very ill or have a poorly functioning immune system.[NCCIH]
Compare brands: Align vs Culturelle · Florastor vs Culturelle.
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