Lactobacillus plantarum is a probiotic bacterium commonly used in dietary supplements. Its use in diverticulitis is based on emerging, but still limited, scientific evidence. The rationale for its use is that probiotics may help restore healthy gut microbiota, reduce inflammation, and support intestinal barrier function, which are relevant in diverticular disease and its complications. A few small randomized controlled trials and observational studies have examined the use of probiotics, including L. plantarum, in diverticular disease (more often in symptomatic uncomplicated diverticular disease rather than acute diverticulitis). For example, one randomized trial found that a formulation containing L. plantarum improved symptoms and reduced inflammation in patients with symptomatic diverticular disease. However, evidence specifically for acute diverticulitis is weak, as most studies focus on prevention of recurrence or symptom management rather than acute treatment. Systematic reviews conclude that while probiotics may have modest benefits for symptom control in diverticular disease, the evidence is insufficient and inconsistent to recommend their routine use in acute diverticulitis. Therefore, the use of L. plantarum in diverticulitis can be considered to have a scientific rationale, but the clinical evidence is limited and not strong enough to firmly support its use. More high-quality, large-scale clinical trials are needed to establish efficacy and optimal strains/dosages for this indication.