The use of botanical extracts as food supplements has witnessed substantial growth, exemplified by the continuous expansion of the dietary supplements market.
It is crucial to acknowledge that these botanicals contain a variety of bioactive molecules which can potentially impact the gut environment and its microbiota. While research has primarily focused on the prebiotic activity of these compounds (mainly for plant polysaccharides), the whole phytocomplex includes several molecules such as polyphenols, catechins, saponins, tannins and terpenes, that work in synergy and exert a broad spectrum of biological effects, including antimicrobial activity against both gram-negative and gram-positive bacteria.1
Although such antimicrobial activity is often considered beneficial for inhibiting pathogenic bacteria, it may also affect the existing microbiota, including microorganisms with health-promoting functions. Maintaining a balanced microbiota is crucial for its proper functioning, as disturbance in composition may cause dysbiosis and has been linked to various disorders.2
With this in mind, food supplements should be formulated with gut-friendly ingredients, meaning they must respect the gut ecosystem and preserve the microbiota diversity in order to maintain the intestinal homeostasis.
Given these considerations, Giellepi is carrying out a research project in collaboration with the Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Italy, aimed to ascertain the gut-friendly properties of its functional branded ingredients, to add value to its clinically proven target benefits.
In the first experimental phase, three plant-based raw materials were studied: a natural phytochemically-characterised extract from the root of Astragalus membranaceus designed to sustain everyday joint and muscle functions (Axtragyl®); a clinically researched phytocomplex for cardiometabolic health derived from Citrus bergamia Risso by-products (Kalita®); and a pure bromelain enzymatic complex isolated from pineapple stem which retains its bioactivity following gastrointestinal transit without enteric-coating (Bromeyal®).
Recognising that these ingredients, following oral intake, undergo alteration before reaching the gut, an in vitro digestion simulation was performed according to the INFOGEST protocol, covering all three phases: oral, gastric, and intestinal.3 Additionally, each ingredient underwent testing on single bacterial strains of health significance, selected to represent the intestinal microbiome or bacteria with established health benefits.
The initial step in the study involved the preparation and characterisation of a faecal suspension to ensure the acquisition of a microbiologically stable and standardised faecal microbiome for subsequent incubations with the three study products.
The three Giellepi’s ingredients were administered either in their original form or following in vitro digestion and added to faecal slurry aliquots at three different concentrations, all under anaerobic conditions.
The samples then underwent metataxonomic analysis and profiling. The 16S rRNA gene amplicons underwent sequencing and diversity analyses delved into both alpha and beta diversity using various indexes. To identify significantly different taxa, the Wilcoxon-Mann-Whitney test was conducted on read abundances subjected to centred log ratio (CLR) transformation, enhancing statistical robustness and accuracy.
Additionally, their impact on individual bacterial strains was evaluated by cultivating the bacteria in the presence of varying concentrations of each plant-based ingredient. All test tubes were inoculated with a bacterial concentration of 10^6 cells/ml, determined through flow cytometry. Positive control samples included the bacterial inoculum without the product, while negative product controls featured the products without the bacterial inoculum.
The viability of the bacteria was assessed by enumeration after dilution, followed by plating onto the appropriate media at 0, 24, and 48 hours. Examples of beneficial strains tested are Lactobacillus acidophilus, Bifidobacterium animalis subs. lactis, Bifidobacterium longum subs. longum, Faecalibacterium prausnitzii, Roseburia intestinalis and Akkermansia muciniphila. Finally, Collinsella aerofaciens was also included as an example of a potentially harmful strain.
From the results of the present experimental study, it was possible to infer that Axtragyl®, Bromeyal® and Kalita® did not have a negative impact on the microbiota present in the faecal samples. α- and β-diversity remained stable during incubations with all tested products, regardless of conditions. This observation extends to the relative abundance of the major bacterial taxa in each sample.
Analysing the abundance of individual species, genera, and bacterial families revealed some beneficial changes, including a decrease in the abundance of Collinsella aerofaciens caused mainly by Axtragyl® and Bromeyal®. Several studies have reported that this bacterium, belonging to the Coriobacteriaceae family, is widely present in the human intestinal microbiota and appears to be expanded in patients with inflammatory bowel diseases (IBD).4,5 On the other hand, an increase in the abundance of Akkermansia muciniphila mainly by Kalita® and Bifidobacteria by Bromeyal® and Axtragyl® was also recorded.
Notably, these findings demonstrate that the three investigated botanicals may exert a positive influence on the bacterial community structure of the healthy human gut microbiota with inhibition of microbial groups associated with potential negative impacts on human health and promotion of health promoting bacteria.
Importantly, experiments conducted with individual strains of human intestinal bacteria revealed no adverse effects on growth, even at concentrations well above those realistically achievable through the oral consumption of these products.
In conclusion, the present study suggests that the tested food supplements ingredients can impart their positive health benefits without disrupting the equilibrium of the human intestinal microbiota qualifying Axtragyl®, Bromeyal® and Kalita® as gut-friendly solutions. It is essential to note that the actual innocuity for the gut microbiome should be assessed individually for each specific botanical product.
With its gut-friendly botanical solutions, Giellepi aims to step into a new era of added value branded ingredients that are tested for their target health benefits while maintaining the natural balance of the gut microbiota ecosystem.
References
1. Cowan M. M. (1999). Plant products as antimicrobial agents. Clinical microbiology reviews, 12(4), 564–582.
2. Revel-Muroz, A.; Akulinin, M.; Shilova, P.; et al. (2023). Stability of human gut microbiome: Comparison of ecological modelling and observational approaches. Computational and structural biotechnology journal, 21, 4456–4468.
3. Brodkorb A.; Egger L.; Alminger M.; et. al. (2019). INFOGEST static in vitro simulation of gastrointestinal food digestion. Nature Protocols. 14:4, 991–1014.
4. Altomare, A.; Di Rosa, C.; Imperia, E.; et al. (2021). Diarrhea Predominant-Irritable Bowel Syndrome (IBS-D): Effects of Different Nutritional Patterns on Intestinal Dysbiosis and Symptoms. Nutrients, 13(5), 1506.
5. Olendzk B.; Bucci V.; Cawley C.; et al. 2022. Dietary manipulation of the gut microbiome in inflammatory bowel disease patients: Pilot study. Gut Microbes, 14:1, 2046244.
