## 4 Discussion  
The MD incorporates a wide variety of plant-based foods, including fruits, vegetables, whole grains, nuts, seeds, and herbs [32]. Besides its richness in essential nutrients, fibers, and vitamins, the components of the MD are rich in polyphenols. The potential effects of these substances are mainly dependent on their interaction with the gut barrier, where polyphenols may contribute to the modulation of gut microbiota by increasing the beneficial bacteria and decreasing the overgrowth of pathogenic bacteria. On the other hand, the gut microbiota may bio-transform polyphenols to increase their bioavailability [33]. Understanding the physiological interactions of components/substances in the MD with gut microbiota and gut barrier is of key importance and has attracted the attention of researchers worldwide. _Thymbra spicata_ is rich in polyphenols and essential oils with a long-standing history and tradition of use in the Eastern Mediterranean region for medical and foods purposes. _Thymbra spicata_ is a thyme-like plant belonging to the _Lamiaceae_ family [12]. Recently, _T. spicata_ has gained much popularity as a remedy to combat different metabolic disorders [34]. A protective role of _T. spicata_ was also reported as it was used as an anti-genotoxic [35] and anti-coagulant agent [36]. However, aspects including the nutritional value and the physiological interaction between the ingested _T. spicata_ and the gut have still not been identified. In this preliminary study, we assessed, for the first time, the nutritional and caloric profiles of _T. spicata_ leaves. These aspects may give important insight into the nutritional and bio-functional characteristics of _T. spicata_, helping us to better understand its physiological interaction with gut microbiota and the intestinal barrier, which were assessed by well-established in vitro models. _T. spicata_ contains a considerable amount of fiber and unsaturated fatty acids, as well as CVL (polyphenols). In line with its high fiber content, we found an increase in the production of SCFAs after microbial fermentation. A growing body of scientific research supports the potential health benefits of dietary polyphenols on the gastrointestinal tract and the gut microbiota. Plant-based polyphenols undergo metabolization and biotransformation during gastrointestinal digestion, and through their interaction with the gut microbiota. Polyphenols and their metabolites then exert several effects on the human gastrointestinal tract, including the modulation of gut microbiota, the improvement of the intestinal barrier, and a reduction in inflammation and oxidative stress [37]. We previously reported the possible antisteatotic and antioxidant effects of _T. spicata_ on the in vitro hepatic steatosis model, whereby we proved that _T. spicata_ ameliorated hepatic steatosis by reducing lipid droplet numbers and sizes, intracellular ROS production, and lipid peroxidation [12]. CVL, a monoterpene phenolic compound, is the main compound of _T. spicata_ essential oils and alcoholic extracts. Previously, we reported an antisteatotic effect, as well as the albumin-binding properties in a high-fat environment, of CVL using in vitro models [27]. In addition, we have recently reported possible patterns of phenolic compounds in _T. spicata_ and their bioactivity during gastrointestinal transit via a simulated in vitro gastrointestinal (GI) digestion of _T. spicata_[28]. The simulated GI digestion reduced the phytochemical contents in _T. spicata_ extracts but improved their antioxidant potential. Given their beneficial effects, _T. spicata_ and CVL were additionally investigated in this study in term of their physiological interaction with gut barriers. We incubated the digested _T. spicata_ with a fecal microbiota fermentation model to understand the possible effects of _T. spicata_ on the growth of human microbiota. _T. spicata_ tended to reduce bacterial growth. Due to its richness in essential oils, especially CVL, _T. spicata_ might exert an antimicrobial effect [17; 18; 19; 38].