Lactobacillus salivarius is a probiotic bacterium that has been studied for its potential benefits in supporting gastrointestinal health, including the small intestine. Scientific evidence indicates that L. salivarius may help maintain the balance of intestinal microflora, inhibit pathogenic bacteria, and modulate immune responses in the gut. Several in vitro and animal studies, as well as some human clinical trials, have demonstrated that supplementation with L. salivarius can reduce inflammation, enhance mucosal barrier function, and decrease the colonization of harmful bacteria such as Escherichia coli and Clostridium difficile.

Specific to the small intestine, L. salivarius has been shown to survive transit through the gastrointestinal tract and temporarily colonize the small bowel. This can contribute to a healthier microbial environment, potentially reducing symptoms associated with small intestinal bacterial overgrowth (SIBO) or functional gastrointestinal disorders. However, while there is promising evidence, most human studies are preliminary or involve small sample sizes. Therefore, the strength of evidence is moderate (rated as 3), and further large-scale, well-controlled clinical trials are needed to confirm its efficacy in directly supporting small intestine health.

In summary, the use of L. salivarius for small intestine support is primarily justified by emerging scientific research, but more robust data are required for definitive conclusions.