Reference Number: 67
Dietary phenolic compounds are often transformed before absorption. This transformation modulates their biological activity. Different studies have been carried out to understand gut microbiota transformations of particular polyphenol types and identify the responsible microorganisms. Although there are potentially thousands of different phenolic compounds in the diet, they are typically transformed to a much smaller number of metabolites. The aim of this review was to discuss the current information about the microbial degradation metabolites obtained from different phenolics and their formation pathways, identifying their differences and similarities. The modulation of gut microbial population by phenolics was also reviewed in order to understand the two-way phenolic?microbiota interaction. Clostridium and Eubacterium genera, which are phylogenetically associated, are other common elements involved in the metabolism of many phenolics. The health benefits from phenolic consumption should be attributed to their bioactive metabolites and also to the modulation of the intestinal bacterial population.
SIGNIFICANCE OF THIS STUDY
Polyphenols are a class of health promoting simple or complex compounds that are present in plant based foods. Simple polyphenols are more easily absorbed in the small intestine following consumption. However, complex polyphenols need to be broken down by specific microbes present in the large intestine or colon. Metabolites (substances formed during the breakdown/metabolism) of food polyphenols play an important role in the health benefits of fruits and vegetables. Many complex dietary phenolics undergo similar transformations (i.e broken down) in the gut by means of microbial enzymes and release the simpler, easily absorbable compounds, which may then be directly absorbed into the blood stream from the colon. This could probably explain some common health benefits observed after the intake of foods with very diverse phenolic compositions. The degree of degradation however of many phenolic compounds is significantly influenced by the amount of phenolic compounds present in the diet as well as individual variations in the composition of the colonic microbiota. This could be the reason why there exists large inter-individual variability in the health benefits observed, which has been attributed to dissimilarities in the populations and type of microbes present in the colon. This paper therefore suggests that it is important to have a better understanding of the dietary phenolic and gut microbiota relationship which could help in the prevention of intestinal diseases, such as inflammatory bowel diseases and colon cancer, as well as in improvement of human health avoiding other chronic diseases.