Researchers at the Ajou University School of Medicine and CHA University School of Medicine conducted a double-blind RCT to determine the dose-dependent effects of synbiotics on gastrointestinal symptoms of and fatigue in IBS.
Synbiotics against symptoms
They recruited 30 subjects with IBS, and randomly assigned them to three groups: subjects in the placebo group each received two capsules of placebo daily, those in the first treatment group each received a high dose of synbiotics (two capsules) daily, and those in the second treatment group were given a low dose of synbiotics (one capsule of synbiotics and one capsule of placebo) daily.
The treatment period lasted eight weeks. At baseline and after treatment, they were asked to complete study questionnaires.
Two subjects in the high-dose group dropped out during the follow-up period, leaving a total of 28 for the final analysis.
After eight weeks, the researchers observed significant differences in abdominal discomfort, abdominal bloating, frequency of formed stool, the fatigue Visual Analogue Scale (VAS) and the Multidimensional Fatigue Inventory among the groups.
They also noted that only abdominal discomfort and bloating, as well as frequency of formed stool, and the fatigue VAS saw marked improvement in the high-dose group when compared with the placebo group.
There were also significant differences among the groups when it came to the frequency of formed stool, but after the Mann-Whitney test with Bonferroni correction, these statistically significant differences — alongside improvements in abdominal discomfort and bloating, and the fatigue VAS — were seen only in the high-dose group.
There were also no significant differences among the groups after eight weeks when it came to to white blood cell count, levels of haemoglobin, platelet count, AST (aspartate aminotransferase), ALT (alanine aminotransferase), GGT (gamma-glutamyl transferase), BUN (blood urea nitrogen) and creatinine.
The results were consistent with a few previous studies on the optimal dose of synbiotics in IBS. The researchers referenced four relevant RCTs, three of which had positive results and the other a negative result.
They wrote: "This discrepancy may be due to variations in inclusion criteria for the subjects, sample size, study design, and synbiotic dosage. Of these heterogeneous factors, our study suggests that dosage plays an important role in the therapeutic effects of IBS.
"This finding may also be supported by our data. Although no significant dose-dependent clinical effects of synbiotics were observed, a trend toward a dose-response relationship was observed."
Optimal conditions for future studies
The current study may have been limited by its small sample size, as well as the researchers being unable to to perform sub-group analysis by IBS sub-types as a result.
They added that a large-scale prospective study was needed to investigate the efficacy of synbiotics on gastrointestinal symptoms and fatigue in IBS sub-types.
They also did not perform any direct measurement of faecal microbial levels for the restoration of normal flora following synbiotic supplementation, though probiotics and prebiotics had been shown previously to be able to modify the gut flora of healthy individuals.
However, they also stated that an eight-week study period may have been too short to confirm the long-term benefits and side effects of synbiotics, and that this was the first to evaluate the dose-response relationship between synbiotics and gut symptoms and fatigue associated with IBS.
In conclusion, the researchers wrote: "This study indicates that high-dose synbiotics containing Lactobacillus, Bifidobacterium, and fructooligosaccharides are effective and safe for the treatment of abdominal discomfort, abdominal bloating, formed stool frequency, and fatigue symptoms in IBS.
"In addition, although were no significant dose-dependent clinical effects of synbiotics were noted, a trend toward a dose-response relationship was demonstrated.
"In the future, further large-scale studies to determine the association between optimal dosage of synbiotics and IBS are warranted."
Source: Korean Journal of Family Medicine
"A Randomized Clinical Trial of Synbiotics in Irritable Bowel Syndrome: DoseDependent Effects on Gastrointestinal Symptoms and Fatigue"
Authors: Sang-Hoon Lee, et al.