Targeted Colostrum Bioactive Proteins Improve Gastrointestinal Symptoms and Modulate the Gut Microbiome: A Randomised Double-Blind Placebo-Controlled Trial

Background: Gastrointestinal (GI) symptoms such as indigestion, bloating and reflux are common and can negatively affect quality of life. Bovine colostrum is a rich source of nutrients and other bioactive constituents that has been shown to be beneficial for gut health. Methods: This 12-week, randomised, double-blind, placebo-controlled, 3-arm study aimed to evaluate the effects of MaolactinGI™, a proprietary bovine colostrum supplement, on upper GI symptoms and gut microbiome composition in healthy adults aged 18 years and older experiencing moderate GI discomfort. Participants completed a 4-week run-in period followed by an 8-week intervention period. Outcomes measured included changes in upper GI symptoms via the Gastrointestinal Symptom Rating Scale (GSRS), Gastroesophageal Reflux Disease Questionnaire (GerdQ), Bloating Symptoms Visual Analogue Scale (BSVAS), Digestion-associated Quality of Life Questionnaire (DQLQ), Bristol Stool Chart, intestinal permeability, faecal calprotectin, serum inflammatory markers, gut microbiome analyses, blood safety markers and adverse events. Results: Ninety eligible participants were allocated to either the high-dose (500 mg/day), low-dose (250 mg/day), or placebo groups, and data from 83 participants were analysed. The high-dose MaolactinGI™ group demonstrated statistically significant improvements in the total GSRS score and DQLQ score compared with placebo, suggesting a meaningful reduction in total symptom burden and improved quality of life. The improvements in GSRS were clinically meaningful in size, supporting the practical relevance of MaolactinGI™ for adults experiencing everyday upper GI discomfort. High-dose supplementation also preserved microbial richness relative to placebo (Chao1); exploratory within-group analyses further indicated enrichment of SCFA-associated commensal taxa. The intervention was well tolerated and demonstrated an acceptable safety profile. Conclusions: These findings support the potential of targeted colostrum-derived bioactive protein fractions as a novel nutritional strategy for supporting GI health and microbiome balance.