GNC's Best Digestive Support for Athletes: GNC Gut Health Sport Probiotic has 4 clinically studied strains to improve digestion and energy use while exercising, plus enzymes to optimize protein absorption. Improve GI Comfort & Energy Use: Clinical results show the combination of strains in Sport Probiotic improved gastrointestinal comfort during exercise, as well as helped athletes optimize energy use. Get The Most Out Of Your Protein: Sport Probiotic features a special enzyme blend to optimize your gut's ability to break down protein and absorb it for muscle building. A Strong Defense Starts In The Microbiome: Every daily dose provides 25 billion live, active cultures to replenish your gut and help keep it primed for a healthy immune response. Following Our Gut Since 1935: Sport GNC's founder started selling probiotic-rich yogurt over 90 years ago—and GNC Gut Health continues that legacy with gut-nourishing formulas to support overall wellness.