Lactobacillus reuteri is a probiotic that has been widely studied for its potential health benefits. L. reuteri is an important addition to this blend of strains because it is particularly resistant to changes in acidity, and studies suggest that it may be able to colonize the proximal small intestines (which are closer to the stomach, where many bacteria have a hard time surviving. Studies have also shown that L. reuteri also has the potential to produce antimicrobial and antiviral compounds, and help synthesize vitamins like B12 and folate.