Lactiplantibacillus plantarum is a probiotic bacterium widely studied for its potential benefits in supporting the small intestine and overall gut health. Scientific research has demonstrated that L. plantarum can survive gastric transit and adhere to the intestinal mucosa, particularly within the small intestine. Multiple clinical and preclinical studies suggest that supplementation with L. plantarum may help maintain intestinal barrier integrity, modulate inflammatory responses, and support a balanced gut microbiota.

Human trials have shown that specific strains of L. plantarum can reduce symptoms of irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO), both of which primarily affect the small intestine. For example, L. plantarum 299v has been shown in several randomized controlled trials to alleviate abdominal pain and bloating, which are common in disorders of the small intestine. Mechanistically, this species produces antimicrobial substances (such as plantaricin) that inhibit pathogens and promotes the production of short-chain fatty acids, which nourish the intestinal lining.

However, while the evidence is promising, the strength and consistency of clinical outcomes vary depending on the strain, dosage, and population studied. Therefore, the evidence rating is moderate (3/5), reflecting good support but not universal consensus or applicability across all small intestine-related conditions.