A Randomized, Double-Blind, Placebo-Controlled Trial: The Efficacy of Multispecies Probiotic Supplementation in Alleviating Symptoms of Irritable Bowel Syndrome Associated with Constipation

The intestinal microbiota consists of a wide range of bacterial species [1]. The microbial community resides in the gut of the host establishing a mutually beneficial relationship and modulating, through its metabolic activities, the host’s health status [2, 3]. The microbiota exerts different physiological functions such as inhibition of pathogenic bacteria and synthesis of short fatty acids; stimulation of nutrient and mineral absorption, as well as modulation of the intestinal immune system; synthesis of vitamins and amino acids; and the decomposition of protein compounds [4, 5].

The intestinal microbiota in healthy adults is generally considered stable over time in predominance of bacteria belonging to four main phyla: Bacteroidetes and Firmicutes as prevalent and Actinobacteria and Proteobacteria that are less represented. The microbiota in subjects with Irritable Bowel Syndrome (IBS) has been shown to be less stable compared to healthy adults [5, 6]. A controlled balance between bacterial species considered beneficial (lactobacilli and bifidobacteria) associated with the reduction of those considered harmful (Clostridium, E. coli, Salmonella, and Pseudomonas) is fundamental for maintenance of the gut physiological state and should attenuate IBS symptoms. Alteration of the microbiota’s composition, which can be caused by psychophysical, dietary, or environmental stress, is defined as dysbiosis and can lead…