Lactobacillus plantarum is a widely studied probiotic species, and there is moderate scientific evidence supporting its use for small intestine health, particularly in the context of digestive balance and gut barrier function. Research indicates that L. plantarum can help modulate the gut microbiota, improve symptoms of irritable bowel syndrome (IBS), and enhance intestinal barrier integrity. Several clinical studies have shown that supplementation with L. plantarum can reduce bloating, abdominal pain, and regulate bowel movements in individuals with mild to moderate gastrointestinal disturbances. In vitro and animal studies also demonstrate that L. plantarum can inhibit the growth of pathogenic bacteria and reduce inflammation in the gut.

While L. plantarum is not specific to the small intestine alone—since probiotics generally act throughout the gastrointestinal tract—there is evidence that it can survive transit through the upper GI tract and transiently colonize the small intestine, where it may exert beneficial effects. However, long-term colonization is rare, and effects are often dependent on continued supplementation. Overall, the evidence is strongest for general gut health and some functional GI disorders, rather than for specific diseases of the small intestine. Thus, the scientific rating is moderate (3/5): there is support for its use, but more rigorous, targeted studies are needed to fully validate its specific benefits for small intestine health.