Lactobacillus reuteri has been studied for its potential to alleviate constipation in children, with particular attention paid to L. reuteri DSM 17938 strain. Several randomized controlled trials (RCTs) have explored its efficacy in pediatric functional constipation. For instance, a 2014 double-blind, placebo-controlled study published in "Pediatrics" (Weizman et al.) found that children receiving L. reuteri experienced increased frequency of bowel movements compared to placebo. Another meta-analysis in "JAMA Pediatrics" (2017) reviewed multiple RCTs and concluded that while L. reuteri may improve stool frequency, its effect on stool consistency and overall treatment success is modest. The proposed mechanisms include improved gut motility, modulation of the gut microbiota, and reduction of intestinal inflammation.

However, not all studies have found significant benefits, and results can vary depending on study design, duration, and constipation criteria. Guidelines from professional societies, such as the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN), currently do not recommend routine use of probiotics, including L. reuteri, for pediatric constipation due to inconsistent evidence. Nonetheless, L. reuteri is widely available and often used in clinical practice, particularly when conventional treatments are insufficient or not tolerated. Overall, while there is scientific evidence supporting its use, the strength of evidence is moderate, and further high-quality studies are needed to establish definitive recommendations.