NOW's **Saccharomyces boulardii** delivers 10 billion CFU per capsule — a full daily dose of the probiotic yeast best known for preventing antibiotic-associated diarrhea. That single capsule already matches the top of the range used across the 100+ clinical trials behind it, so you don't need to stack capsules to reach an effective amount. Unlike bacterial probiotics, this yeast naturally shrugs off stomach acid and bile, so more of it survives the trip to your gut intact.
One thing worth knowing: the strongest evidence — the meta-analyses showing it roughly halves the risk of diarrhea during antibiotic courses — was built mostly on a specific reference strain (CNCM I-745). This product uses the closely related I-3799 strain, which shares the species' track record but hasn't been trialed as heavily on its own. It also needs refrigeration — keep it cold so the live cells survive to do their job.
BioStacks
Other Ingredients (3)
InulinFiller
Prebiotic soluble fiber from chicory root, used as a filler and flow agent in capsules and tablets
Guar GumThickener
Natural thickener derived from guar beans
HypromelloseCapsule
Plant-derived capsule material from cellulose
How to Take It
Take it anytime
Timing doesn't matter for this one — taking it consistently does.
With or without food
Split into 2 doses across the day
On the label
Suggested Usage: Take 1-2 capsules 2 to 3 times daily between meals as needed.
General guidance based on the ingredients, not a substitute for the label or your doctor.
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Sources & Scoring
Nutrient data (RDA, UL, and safety thresholds) sourced from: NIH Office of Dietary Supplements and National Academies Dietary Reference Intakes (DRI).
This is not medical advice. Consult a healthcare provider before making changes to your supplement routine.
The score analyzes what's on the label: ingredient doses vs. clinical ranges, chemical forms, evidence levels, and known interactions. It does not verify label accuracy or test for contaminants — for that, look for third-party certifications like USP or NSF.