Thorne Sacro-B

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.