Gut Microbiota is Not Modified by Randomized, Double-Blind, Placebo-Controlled Trial of VSL#3 in Diarrhea-Predominant Irritable Bowel Syndrome

Abstract

Irritable Bowel Syndrome (IBS) is a common condition that negatively impacts the quality of life for many individuals. The exact etiology of this disorder is largely unknown; however, emerging studies suggest that the gut microbiota is a contributing factor. Several clinical trials show that probiotics, such as VSL#3, can have a favorable effect on IBS. This double-blind, randomized placebo-controlled study has been conducted in diarrhea-predominant IBS subjects in order to investigate the effect of VSL#3 on the fecal microbiota. The bacterial composition of the fecal microbiota was investigated using high-throughput microarray technology to detect 16S RNA. Twenty four subjects were randomized to receive VSL#3 or placebo for 8 weeks. IBS symptoms were monitored using GSRS and quality of life questionnaires. A favorable change in Satiety subscale was noted in the VSL #3 groups. However, the consumption of the probiotic did not change the gut microbiota. There were no adverse events or any safety concerns encountered during this study. To summarize, the use of VSL#3 in this pilot study was safe and showed improvement in specific GSRS-IBS scores in diarrhea-predominant IBS subjects. The gut microbiota was not affected by VSL#3 consumption suggesting that the mechanism of action is not directly linked to the microbiota.

Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It?

“…However, we are aware of the fact that this may be biased by the respective authors that tend to underestimate or undervalue negative results, for instance in comparison to registered trial reports. 81,82 We found that 14 of the 27 studies reported negative outcome on global symptoms, however individual symptoms (bloating 67,77 and satiety 69 ) were occasionally reported as being responsive to treatment. Quality of life (QoL) improved in one study but symptomatic improvement was not different from placebo.…”

“…One study included patients with functional gastrointestinal disorders, ie, with diarrhea but not constipation and not necessarily suffering from abdominal pain, 72 one was restricted to constipation predominant IBS (IBS-C) patients 65 and 4 included only diarrhea predominant IBS (IBS-D) patients. 62,68,69,80 All studies claimed the use of Rome (II or III) criteria, nevertheless, a more detailed description of the patient population (the number of IBS-D, IBS-C, and mixed IBS [IBS-M] patients) was lacking. Treatment duration varied from 7 days to 6 months, thus not fulfilling Rome criteria for treatment duration in many cases, 17 with the majority of studies assessing treatment results after 8 weeks.…”

“…The same preparation (VSL#3) was used in only 3 studies. 69,77,80 Up to 8 different bacterial strains are used in some preparations and the combinations are numerous, since in many cases subspecies of specific strains were used that are only available to (and eventually patented by) individual companies. Two studies were performed by the same research group with the same preparation.…”

Modulation of the gut microbiota: a focus on treatments for irritable bowel syndrome

“…However, Michail et al [87] showed no differences from baseline in the number of bacteria or the diversity of bacterial species after 4-or 8-week treatment with VSL #3. The efficacy of the probiotic VSL #3 has been examined in four clinical studies of patients with IBS [87][88][89][90]; overall, the efficacy of VSL#3 was similar to that of placebo, although flatulence improved significantly with VSL#3 versus placebo after 4 and 8 weeks in one study ( …”

“…15 cm from the anal verge) of patients with IBS, with twice daily treatment for 4 weeks, leading to an increase from baseline in average abundance of Bifidobacterium, Lactobacillus, and Streptococcus and a decrease from baseline in Bacteroides average abundance to levels comparable with that of the mucosa of healthy individuals [86]. However, Michail et al [87] showed no differences from baseline in the number of bacteria or the diversity of bacterial species after 4-or 8-week treatment with VSL #3. The efficacy of the probiotic VSL #3 has been examined in four clinical studies of patients with IBS [87][88][89][90]; overall, the efficacy of VSL#3 was similar to that of placebo, although flatulence improved significantly with VSL#3 versus placebo after 4 and 8 weeks in one study ( …”