Human gut microbiota fermentation of cooked eggplant, garlic, and onion supports distinct microbial communities.

Heating and cooking vegetables not only enhances their palatability but also modifies their chemical structure, which in turn might affect their fermentation by resident gut microbes. Three commonly consumed vegetables that are known to undergo chemical browning, also known as Maillard reaction, during cooking - eggplant, garlic, and onion - were each fried, grilled, or roasted. The cooked vegetables were then subjected to an in vitro digestion-fermentation process aimed to simulate the passage of food through the human oro-gastro-intestinal tract. In the last step, the undigested fractions of these foods were anaerobically fermented by the complex human gut microbiota. We assessed the structure of microbial communities maintained on each cooked vegetable by high-throughput 16S rRNA gene amplicon sequencing, measured the levels of furosine, a chemical marker of the Maillard browning reaction, by HPLC, and determined the antioxidant capacities in all samples with ABTS and FRAP methods. Overall, vegetable type had the largest, statistically significant, effect on the microbiota structure followed by the cooking method. Onion fermentation supported a more beneficial community including an expansion of Bifidobacterium members and inhibition of Enterobacteriaceae. Fermentation of cooked garlic promoted Faecalibacterium growth. Among cooking methods, roasting led to a much higher ratio of beneficial-to-detrimental microbes in comparison with grilling and frying, possibly due to the exclusion of any cooking oil in the cooking process.

Development of an Unified Food Composition Database for the European Project "Stance4Health".

The European Commission funded project Stance4Health (S4H) aims to develop a complete personalised nutrition service. In order to succeed, sources of information on nutritional composition and other characteristics of foods need to be as comprehensive as possible. Food composition tables or databases (FCT/FCDB) are the most commonly used tools for this purpose. The aim of this study is to describe the harmonisation efforts carried out to obtain the Stance4Health FCDB. A total of 10 FCT/FCDB were selected from different countries and organizations. Data were classified using FoodEx2 and INFOODS tagnames to harmonise the information. Hazard analysis and critical control points analysis was applied as the quality control method. Data were processed by spreadsheets and MySQL. S4H's FCDB is composed of 880 elements, including nutrients and bioactive compounds. A total of 2648 unified foods were used to complete the missing values of the national FCDB used. Recipes and dishes were estimated following EuroFIR standards via linked tables. S4H's FCDB will be part of the smartphone app developed in the framework of the Stance4Health European project, which will be used in different personalized nutrition intervention studies. S4H FCDB has great perspectives, being one of the most complete in terms of number of harmonized foods, nutrients and bioactive compounds included.

Green Tea and Its Relation to Human Gut Microbiome.

Green tea can influence the gut microbiota by either stimulating the growth of specific species or by hindering the development of detrimental ones. At the same time, gut bacteria can metabolize green tea compounds and produce smaller bioactive molecules. Accordingly, green tea benefits could be due to beneficial bacteria or to microbial bioactive metabolites. Therefore, the gut microbiota is likely to act as middle man for, at least, some of the green tea benefits on health. Many health promoting effects of green tea seems to be related to the inter-relation between green tea and gut microbiota. Green tea has proven to be able to correct the microbial dysbiosis that appears during several conditions such as obesity or cancer. On the other hand, tea compounds influence the growth of bacterial species involved in inflammatory processes such as the release of LPS or the modulation of IL production; thus, influencing the development of different chronic diseases. There are many studies trying to link either green tea or green tea phenolic compounds to health benefits via gut microbiota. In this review, we tried to summarize the most recent research in the area.

Green and white teas as health-promoting foods.

Tea is one of the most consumed beverages around the world and as such, it is constantly the object of novel research. This review focuses on the research performed during the last five years to provide an updated view of the current position of tea regarding human health. According to most authors, tea health benefits can be traced back to its bioactive components, mostly phenolic compounds. Among them, catechins are the most abundant. Tea has an important antioxidant capacity and anti-inflammatory properties, which make this beverage (or its extracts) a potential aid in the fight against several chronic diseases. On the other hand, some studies report the possibility of toxic effects and it is advisable to reduce tea consumption, such as in the last trimester of pregnancy. Additionally, new technologies are increasing researchers' possibilities to study the effect of tea on human gut microbiota and even against SARS CoV-2. This beverage favours some beneficial gut microbes, which could have important repercussions due to the influence of gut microbiota on human health.

Spent Coffee Grounds Extract, Rich in Mannooligosaccharides, Promotes a Healthier Gut Microbial Community in a Dose-Dependent Manner.

Coffee is one of the most consumed beverages around the world, and as a consequence, spent coffee grounds are a massively produced residue that is causing environmental problems. Reusing them is a major focus of interest presently. We extracted mannooligosaccharides (MOS) from spent coffee grounds and submitted them to an in vitro fermentation with human feces. Results obtained suggest that MOS are able to exert a prebiotic effect on gut microbiota by stimulating the growth of some beneficial genera, such as Barnesiella, Odoribacter, Coprococcus, Butyricicoccus, Intestinimonas, Pseudoflavonifractor, and Veillonella. Moreover, short-chain fatty acids (SCFA) production also increased in a dose-dependent manner. However, we observed that 5-(hydroxymethyl)furfural, furfural, and polyphenols (which are either produced or released from the spent coffee grounds matrix during hydrolysis) could have an inhibitory effect on other beneficial genera, such as Faecalibacterium, Ruminococcus, Blautia, Butyricimonas, Dialister, Collinsella, and Anaerostipes, which could negatively affect the prebiotic activity of MOS.

Effect of in vitro digestion-fermentation on green and roasted coffee bioactivity: The role of the gut microbiota.

Coffee is one of the most consumed beverages and has been linked to health in different studies. However, green and roasted coffees have different chemical composition and therefore their health properties might differ as well. Here, we study the effect of in vitro digestion-fermentation on the antioxidant capacity, phenolic profile, production of short-chain fatty acids (SCFAs), and gut microbiota community structure of green and roasted coffee brews. Roasted coffees showed higher antioxidant capacity than green coffees, with the highest level achieved in fermented samples. Polyphenol profile was similar between green and roasted coffees in regular coffee brews and the digested fraction, but very different after fermentation. Production of SCFAs was higher after fermentation of green coffee brews. Fermentation of coffee brews by human gut microbiota led to different community structure between green and roasted coffees. All these data suggest that green and roasted coffees behave as different types of food.

High Antioxidant Action and Prebiotic Activity of Hydrolyzed Spent Coffee Grounds (HSCG) in a Simulated Digestion-Fermentation Model: Toward the Development of a Novel Food Supplement.

Spent coffee grounds are a byproduct with a large production all over the world. The aim of this study was to explore the effects of a simulated digestion-fermentation treatment on hydrolyzed spent coffee grounds (HSCG) and to investigate the antioxidant properties of the digestion and fermentation products in the human hepatocellular carcinoma HepG2 cell line. The potentially bioaccessible (soluble) fractions exhibited high chemoprotective activity in HepG2 cells against oxidative stress. Structural analysis of both the indigestible (insoluble) and soluble material revealed partial hydrolysis and release of the lignin components in the potentially bioaccessible fraction following simulated digestion-fermentation. A high prebiotic activity as determined from the increase in Lactobacillus spp. and Bifidobacterium spp. and the production of short-chain fatty acids (SCFAs) following microbial fermentation of HSCG was also observed. These results pave the way toward the use of HSCG as a food supplement.