Soy fiber is primarily used to support the rectum and overall lower digestive tract health due to its well-established role as a dietary fiber. Scientific studies have demonstrated that dietary fibers, including those derived from soy, increase stool bulk, improve stool consistency, and promote regular bowel movements. This is particularly relevant for supporting rectal health, as increased fiber intake can help prevent or alleviate constipation and reduce straining during defecation, which are risk factors for rectal disorders such as hemorrhoids and anal fissures.

Clinical research has shown that soy fiber, which is mainly insoluble, is effective in increasing stool weight and reducing intestinal transit time. A number of randomized controlled trials and reviews (e.g., Spiller GA, 1994, J Nutr; Slavin JL, 2001, Nutrition) have confirmed the beneficial effects of soy fiber supplementation on bowel function. While most of the data on fiber and rectal health come from studies on fiber in general (including wheat bran, psyllium, and others), soy fiber is included among the sources with demonstrated efficacy.

Therefore, the use of soy fiber to support the rectum and promote healthy bowel habits is justified by scientific evidence, although it is not unique to soy fiber and applies to dietary fiber broadly.