Product Description
Race travel, training camps, antibiotic courses, high-carb fueling — endurance athletes hit their gut with a lot. And when the gut goes sideways at the wrong moment, everything else does too. Saccharomyces boulardii is the most clinically documented probiotic for protecting gut function during exactly these high-risk windows, and Thorne Sacro-B delivers it at 5 billion CFUs per delayed-release capsule.
What makes S. boulardii different from every other probiotic on the shelf: it's a yeast, not a bacterium. That one distinction changes everything about how and when it works.
Antibiotic-Proof Gut Protection – Because S. boulardii is a yeast, antibiotics can't kill it. Most bacterial probiotics get wiped out alongside the pathogens antibiotics are targeting. Sacro-B survives the antibiotic course intact, actively protecting the gut lining and supporting the regrowth of beneficial flora while treatment is ongoing — not just after it ends.
Clinically Proven Defense Against Travel Issues – Clinical trials across thousands of travelers found S. boulardii significantly reduced the incidence of traveler's diarrhea in a dose-dependent manner. For athletes racing or training abroad, it's the most evidence-backed gut protection tool available — start it five days before travel and continue through the trip.
Strengthens Gut Immunity from the Inside – S. boulardii increases production of secretory IgA, the immune protein that lines and defends the gastrointestinal tract. Higher sIgA means a stronger first-line defense against the pathogens, dietary shifts, and environmental stress that hard-training athletes constantly encounter.
Faster Recovery After Gut Disruption – Whether it's a GI bug, an antibiotic course, or a rough race day, Sacro-B helps restore beneficial gut flora and intestinal barrier function faster. It supports the recovery of the gut environment that efficient nutrient absorption — and everything downstream of it — depends on.
How to Use Thorne Sacro-B
Daily Dose: Take 1 capsule one to three times daily between meals. For travel protection, begin five days before departure and continue through the trip.
Timing: Between meals is optimal — stomach acid levels are lower outside of meal windows, giving the yeast the best conditions to reach the intestines intact. Sacro-B's delayed-release capsule adds an additional layer of protection.
Pro Tip: On antibiotics? Start Sacro-B the same day as your antibiotic prescription and continue for a few days after the course ends. Unlike bacterial probiotics, it doesn't need to be spaced away from your antibiotic dose.
Your gut is the foundation. Keep it working when the conditions are working against it.
- Gluten free
Supplement Facts
60 Servings
Serving Size: One Capsule
Serving Per Container: 60
| Amount Per Serving | ||
|---|---|---|
| % Daily Value* | ||
| Saccharomyces boulardii (CNCM I-3799) 250mg | ** | |
* Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.
** Daily Value (DV) not established
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Thorne Sacro-B FAQ's
Everything you need to know about Thorne Sacro-B.
Start it three to five days before travel, antibiotic use, or any situation where you know your gut is going to take a hit. That build-up window matters — Saccharomyces boulardii reaches a stable concentration in your colon within about three days of consistent use, so waiting until your stomach is already in trouble means you're playing catch-up instead of staying ahead of it. For general training support, take one capsule one to three times daily between meals.
Yes — and this is one of the most important reasons to keep it in your kit. Saccharomyces boulardii is a yeast, not a bacterium, which means antibiotics literally cannot kill it. While antibiotics are wiping out the beneficial bacteria in your gut, Sacro-B keeps working the whole time. Every other probiotic you own — all the bacterial strains — get destroyed alongside the bad bacteria during an antibiotic course. Sacro-B doesn't. Take them at the same time without any concern.
Most probiotics are bacterial — they colonize your gut and work long-term, but they're completely vulnerable to antibiotics, heat, and the harsh environment of your stomach. Saccharomyces boulardii is a yeast, which makes it fundamentally different in three ways: antibiotics can't touch it, it survives stomach acid without needing special encapsulation, and it works transiently rather than permanently — it does its job while you're taking it, then clears your system within a few days of stopping. That transient mechanism is actually a feature, not a bug. It means no risk of overgrowth.
It works through your gut's immune system. Saccharomyces boulardii stimulates production of secretory IgA — your gut's front-line patrol protein that identifies and neutralizes threats before they take hold in the intestinal lining. More sIgA means your gut handles unfamiliar food environments, new water sources, race-venue catering, and training-induced gut stress without spiraling into the GI crisis that ruins races. It also crowds out harmful bacteria and supports the growth of your existing beneficial flora at the same time.
No — it's completely shelf-stable. This is a major practical advantage for athletes. Keep it in your race bag, your carry-on, your gym bag — it doesn't care. No cold chain required, no special storage, no worrying about whether it survived a warm luggage hold. Just grab it and go.