Systematic review and meta-analysis of interventions with dietary supplements, including pre-, pro- and synbiotics, to reduce acute and late gastrointestinal side effects in patients undergoing pelvic radiotherapy
Authors: Bartsch Benjamin , Then Chee Kin , Harriss Elinor , Kartsonaki Christiana , Kiltie Anne E. 
Published: August 2020

ABSTRACTObjectivePelvic radiotherapy (RT) often results in toxicity to the gastrointestinal tract and clinical trials have demonstrated a potentially beneficial role of dietary supplements in overcoming this problem, mainly acute effects. This systematic review and meta-analysis were undertaken with the aim of evaluating the efficacy of several dietary supplement interventions in preventing or alleviating symptoms of gastrointestinal toxicity in patients undergoing RT for a range of common pelvic malignancies.DesignThe search protocol was prospectively submitted to PROSPERO at the University of York. CENTRAL, MEDLINE, EMBASE, andhttp://ClinicalTrials.govwere searched up to June 2020 for randomised controlled clinical trials. Interventions included four supplement categories: biotics, amino acids, poly-unsaturated fatty acids and polyphenols. Efficacy was determined with reference to outcomes based on symptoms of acute gastrointestinal toxicity, including diarrhoea, nausea and vomiting.ResultsTwenty-three randomised controlled trials (1919 patients) were identified in this review. Compared with placebo, probiotics, synbiotics and polyphenols were significantly associated with a lower risk of diarrhoea. Biotic supplements also reduced the risk of moderate to severe diarrhoea and the need for anti-diarrhoeal medication. In contrast, amino acid supplements had no effect on acute symptoms. There was a non-significant trend for reduction in nausea and mean bowel movements per day using dietary supplements.ConclusionsBiotic supplements, especially probiotics and synbiotics, reduce acute symptoms of gastrointestinal toxicity in patients undergoing pelvic radiotherapy. More randomised placebo-controlled studies with larger numbers of patients are needed to define specific formulations for supplement interventions that will be of greatest benefit to patients.Summary box1.What is already known about this subject?Clinical trials have indicated a potentially beneficial role of dietary supplements for the prevention and treatment of radiation-induced gastrointestinal symptoms.2.What are the new findings?In this systematic review, we found biotics and polyphenols can significantly reduce the risk of diarrhoea, while biotics were also associated with a lower incidence of moderate to severe diarrhoea and anti-diarrhoeal medication use. Among biotic supplements, both synbiotics and probiotics were found to be potentially beneficial in the prevention of diarrhoea.3.How might it impact on clinical practice in the foreseeable future?Cancer patients undergoing pelvic RT may benefit from taking biotic supplements for alleviation of gastrointestinal toxicity symptoms following pelvic radiation. More randomised controlled trials are required to determine the optimum formulations and combinations.Trial registration numberThe study protocol was published on the PROSPERO international prospective register of systematic reviews (registration number CRD42020183304).