Researchers at Shanghai Hudong Hospital, the Shanghai University of Traditional Chinese Medicine, and Nanjing University of Traditional Chinese Medicine conducted a systematic review and meta-analysis to assess the effects of probiotic supplementation on functional constipation in children.
They searched PubMed, Embase, and Cochrane Library for relevant studies with no language restriction, from the earliest available papers on these databases to March 2018.
They finally included four trials, involving a total of 382 children with functional constipation, and reported "no significant differences in treatment success, spontaneous bowel movements per week, faecal soiling episodes per week, straining at defecation, use of lactulose, use of laxatives, faecal incontinence, pain during defecation, flatulence, and adverse events between probiotics and placebo".
In fact, only one trial reported significant differences in the results between the intervention and control groups — with the former faring more poorly than the latter.
The probiotic strain used in the trial, Lactobacillus casei rhamnosus, was linked to a lower treatment success rate in the intervention group (68% at 12 weeks and 65% at 24 weeks) than in the control group (72% at 12 weeks and 64% at 24 weeks).
There were also no marked differences in spontaneous bowel movements or faecal soiling episodes per week, adverse events, and overall tolerance between both groups at four, eight, and 12 weeks.
However, like the rest of the trials, the researchers reported that the use of probiotics was linked to a lower incidence of abdominal pain, and less frequent use of a glycerine enema (an enema solution with 5% glycerine, a trihydroxy alcohol with osmotic laxative properties).
These observations contradict the results seen in many trials that have been conducted on the gut health benefits of probiotics, including their impact on gastric symptoms, diarrhoea, intestinal health in gastric cancer patients, and gastrointestinal diseases in infants.
Still, there have been other studies and analyses that have cast doubt on the efficacy of probiotics: some have asserted that there is insufficient evidence on the benefits of both probiotics and prebiotics, while others have even called probiotics "useless".
The researchers behind the current study wrote that the findings could have been the result of sample sizes in certain trials that were too small to detect potentially clinically relevant differences between treatment and placebo groups.
They added, "The few trials that reported these outcomes showed no statistically significant differences. Therefore, we simply reported a relative result and provided a synthetic and comprehensive review."
At the same time, they said that publication bias was 'inevitable' as their meta-analysis was based on published studies that might have overestimated the treatment effects of probiotics.
They had also not performed sub-group analysis due to the small number of trials reviewed, and the pooled data from the meta-analysis — used in the absence of individual data — prevented a detailed analysis that could have obtained more comprehensive results.
On the other hand, the researchers stated that the overall large sample size of their review allowed them to quantitatively assess the efficacy of probiotics in children with functional constipation. This meant their findings might have been more robust than those of an individual study.
Furthermore, theirs was the first known meta-analysis to have been performed on children with functional constipation.
In conclusion, they wrote: "The results of this study suggested that probiotic supplementation might result in reduced frequency of glycerine enema use and abdominal pain, but has no significant effect on treatment success, spontaneous bowel movements per week, faecal soiling episodes per week, straining and pain during defecation, use of lactulose and laxatives, faecal incontinence, flatulence, and adverse events.
"Future studies should focus on specific types of probiotics and children with specific characteristics."
"Systematic review and meta-analysis of the effect of probiotic supplementation on functional constipation in children"
Authors: Jin Lei, et al.