Background: Adults and children who are enterally tube-fed can experience adverse gastrointestinal symptoms (GIS). Observational data suggests that blended diets (BD) could mitigate such symptoms, with potential to improve quality of life and clinical outcomes. We present a novel systematic review examining the impact of BD, compared to commercial feeds, on GIS of adults and children who are tube-fed. Methods: The protocol was registered with PROSPERO (CRD42021261147). Four electronic databases were searched from inception to August 2021. Search terms included 'tube-fed', 'blended diet' and 'formula'. Inclusion criteria were intervention studies comparing blended and commercial feeds using quantitative measures of GIS. Heterogeneity of outcome measures precluded meta-analysis; therefore, a narrative synthesis was conducted. Results: Six papers (n = 219), including two randomised control trials (RCT) and four single arm pre-post studies, were identified. Equal numbers studied in-and out-patients, adults and children. Risk of bias was notable for all studies. Equivocal and insufficient evidence prevented consensus on outcomes of vomiting, gagging, oral intake, bloating and constipation. However, one RCT and two single arm pre-post studies suggest that diarrhoea symptoms may be improved on BD. Conclusions: Diarrhoea is prevalent in tube-fed populations and associated with adverse outcomes. Improvements in diarrhoea symptoms attributed to BD may be clinically important. Our findings are congruous with the wider observational evidence base, and support recommendations of the British Dietetic Association. BD may pose a viable alternative to commercial formula, and may mitigate symptoms of diarrhoea for adults and children who are tube-fed.