Glucooligosaccharides (GOS) are a type of prebiotic fiber that is well-documented for their positive effects on gut health, particularly within the small intestine. Prebiotics are non-digestible carbohydrates that promote the growth of beneficial bacteria, such as Bifidobacteria and Lactobacilli, in the gut. Several randomized controlled trials and systematic reviews have demonstrated that GOS supplementation can modulate the gut microbiota, leading to improved intestinal barrier function and enhanced immune response. GOS are resistant to digestion in the upper gastrointestinal tract and reach the small intestine largely intact, where they are selectively fermented by commensal bacteria. This fermentation produces short-chain fatty acids (SCFAs) like butyrate, which are known to support intestinal health and have anti-inflammatory effects.

Studies also report that GOS can help reduce the incidence of infections, support the integrity of the gut lining, and alleviate symptoms of gastrointestinal discomfort, such as those seen in irritable bowel syndrome (IBS). However, most research focuses on general gut health rather than specific effects limited only to the small intestine. The evidence is stronger for modulation of the microbiome and immune effects than for treating any single disease. Overall, the use of GOS to support small intestine health is scientifically justified, though the evidence is moderate and primarily based on studies of prebiotic effects on the gut as a whole rather than targeted studies on the small intestine alone.