Got Diarrhea? Eating Marshmallows Reduces Ileostomy Output: A Randomized Crossover Trial

Who doesn’t love a good marshmallow, a smore etc?  But what on Earth is this study and what even compelled a research study on it? Ok, this article recently floated around some social media circles and was even touted as evidence to make recommendations for patients with good ole diarrhea. I had to see it for myself. The study claims:

“Anecdotally, many ostomates believe that eating marshmallows can reduce ileostomy effluent. There is a plausible mechanism for this, as the gelatin contained in marshmallows may thicken small bowel fluid, but there is currently no evidence that this is effective.”

            I’m all for anecdotes and case reports leading into research, after all, many good ideas start as such, but does this even pass the research plausibility test? The study itself says there is A plausible mechanism for this is that marshmallows contain gelatine, a well‐known thickening agent. Gelatine forms a semi‐solid colloid gel when mixed with water and its high viscosity in solution may explain how the compound thickens and slows fecal effluence in people with ileostomies. 

Could the results which reference ileostomies even be generalized to diarrhea as was claimed? Ok, at least it was a good design being a randomized crossover trial. This is good. Gotta admit it, the method other than participant recall bias wasn’t that bad either:

“Adult patients with well‐established ileostomies were included. Ileostomy output was measured for 1 week during which three marshmallows were consumed three times daily, and for one control week where marshmallows were not eaten. There was a 2‐day washout period. Patients were randomly allocated to whether the control or intervention week occurred first. In addition, a questionnaire was administered regarding patient’s subjective experience of their ileostomy function.”

            Study power was definitely lacking with only 28 participants completing the study. This almost makes it null and void and a type I error where there is rejection of the true null hypothesis – i.e. saying there is a relationship where no discernable relationship exists. But as far as the results P values were significant – participants reported fewer ileostomy bag changes (median five per day vs six in the control period, =0.0255). Twenty of 28 (71%) reported that the ileostomy effluent was thicker during the study week (=0.023). Conclusion: Eating marshmallows leads to a small but statistically significant reduction in ileostomy output. I don’t know, you decide. 

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Robert Duprey MD

Robert is a 2nd career physician (MD); a combat Veteran with the US Army; a former psychiatric nurse practitioner; an independent researcher; a medical writer; and now having passed USMLE Steps 1, 2CK, 2CS, and 3, is a residency applicant.