Study of the prebiotic potential of Althaea officinalis L. root extract using the high throughput ex vivo technology SIFR®

Introduction: The extract of Althaea officinalis L. root is used in irritations of the pharyngeal mucosa and resulting dry cough (1), but also in gastrointestinal complaints. While the underlying mucosa protective and anti-inflammatory effects have been studied thoroughly over the last years, data on ist effect on the gut microbiota are missing. Objective: Given that the extract constituents can be assumed to be not fully absorbed in the small intestine, its influence on the gut microbiota in the large intestine was intended to be studied. Method: The impact of an extract (STW 42, AR) on the gut microbiome was investigated using the high-throughput, ex vivo SIFR® technology (Cyptobiotix, Ghent, Belgium). Considering six subjects individually covered the broad spectrum of microbial compositions that occurs in vivo, in line with the so-called enterotypes, thus ensuring representative findings. Simulating a single intake, AR was dosed at 1.875 g/d and inulin (IN; used as positive control) was dosed at equivalent of 2 g/day. Results and Discussion: AR significantly increased total SCFA and significantly decreased pH. While the extent of the effects was lower than with IN, health-related propionate/butyrate was significantly increased, showing a specific effect on butyrate production, which suggests a product-specific impact on the microbiome. Potent treatment effects were noted at higher phylogenetic resolution (OTU level): AR exerted effects including the consistent stimulation of an OTU related to Ruminiclostridium cellulolyticum. Conclusion: Overall, the SIFR® study demonstrated the prebiotic potential of marshmallow root extract (AR) by its influence on microbial metabolite production and microbial composition.