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Abstract
Purpose
Maltodextrin (MDX) is a polysaccharide food additive commonly used as oral placebo/control to investigate treatments/interventions in humans. The aims of this study were to appraise the MDX effects on human physiology/gut microbiota, and to assess the validity of MDX as a placebo-control.
Methods
We performed a systematic review of randomized-placebo-controlled clinical trials (RCTs) where MDX was used as an orally consumed placebo. Data were extracted from study results where effects (physiological/microbial) were attributed (or not) to MDX, and from study participant outcomes data, before-and-after MDX consumption, for post-publication ‘re-analysis’ using paired-data statistics.
Results
Of two hundred-sixteen studies on ‘MDX/microbiome’, seventy RCTs (n = 70) were selected for analysis. Supporting concerns regarding the validity of MDX as a placebo, the majority of RCTs (60%, CI 95% = 0.48–0.76; n = 42/70; Fisher-exact p = 0.001, expected < 5/70) reported MDX-induced physiological (38.1%, n = 16/42; p = 0.005), microbial metabolite (19%, n = 8/42; p = 0.013), or microbiome (50%, n = 21/42; p = 0.0001) effects. MDX-induced alterations on gut microbiome included changes in the Firmicutes and/or Bacteroidetes phyla, and Lactobacillus and/or Bifidobacterium species. Effects on various immunological, inflammatory markers, and gut function/permeability were also documented in 25.6% of the studies (n = 10/42). Notably, there was considerable variability in the direction of effects (decrease/increase), MDX dose, form (powder/pill), duration, and disease/populations studied. Overall, only 20% (n = 14/70; p = 0.026) of studies cross-referenced MDX as a justifiable/innocuous placebo, while 2.9% of studies (n = 2/70) acknowledged their data the opposite.
Conclusion
Orally-consumed MDX often (63.9% of RCTs) induces effects on human physiology/gut microbiota. Such effects question the validity of MDX as a placebo-control in human clinical trials.
Details
1 Case Western Reserve University, Department of Pathology, Cleveland, USA (GRID:grid.67105.35) (ISNI:0000 0001 2164 3847)
2 Case Western Reserve University School of Medicine, Department of Medicine and Division of Gastroenterology & Liver Diseases, Cleveland, USA (GRID:grid.67105.35) (ISNI:0000 0001 2164 3847); Digestive Health Research Institute, University Hospitals Cleveland Medical Center, Cleveland, USA (GRID:grid.443867.a) (ISNI:0000 0000 9149 4843)
3 Case Western Reserve University School of Medicine, Department of Medicine and Division of Gastroenterology & Liver Diseases, Cleveland, USA (GRID:grid.67105.35) (ISNI:0000 0001 2164 3847); Digestive Health Research Institute, University Hospitals Cleveland Medical Center, Cleveland, USA (GRID:grid.443867.a) (ISNI:0000 0000 9149 4843); University Hospitals Research and Education Institute, University Hospital Cleveland Medical Center, Cleveland, USA (GRID:grid.241104.2) (ISNI:0000 0004 0452 4020)
4 Case Western Reserve University School of Medicine, Department of Medicine and Division of Gastroenterology & Liver Diseases, Cleveland, USA (GRID:grid.67105.35) (ISNI:0000 0001 2164 3847); Digestive Health Research Institute, University Hospitals Cleveland Medical Center, Cleveland, USA (GRID:grid.443867.a) (ISNI:0000 0000 9149 4843); Cleveland Digestive Diseases Research Core Center, Case Western Reserve University, Germ-Free and Gut Microbiome Core, Cleveland, USA (GRID:grid.67105.35) (ISNI:0000 0001 2164 3847); University Hospitals Research and Education Institute, University Hospital Cleveland Medical Center, Cleveland, USA (GRID:grid.241104.2) (ISNI:0000 0004 0452 4020)