Sulfated polysaccharides, particularly those derived from seaweeds such as agar, carrageenan, and alginates, have documented use in the management of constipation, including in children. The scientific rationale centers on their function as dietary fibers—these large, complex carbohydrates are resistant to human digestive enzymes and therefore increase stool bulk and water content through their gel-forming and water-binding properties. This, in turn, stimulates peristalsis and facilitates bowel movements.

Agar, for example, has been traditionally used in Japanese and other Asian diets as a laxative. Several clinical studies and reviews have confirmed the laxative effect of agar and similar seaweed-derived polysaccharides in children and adults. For instance, a review in Pediatric Gastroenterology, Hepatology & Nutrition (2017) mentions the use of agar and other non-absorbable polysaccharides as osmotic laxatives for pediatric constipation, noting their efficacy and safety profile. However, the number of large, high-quality randomized controlled trials specifically in children is limited, and most evidence comes from smaller studies or extrapolation from adult data.

Overall, the use of sulfated polysaccharides for pediatric constipation is scientifically plausible and has some clinical support, particularly for agar. Nonetheless, more robust pediatric-specific research is needed for a stronger evidence base.