Preliminary study about the relationship between non-extractable polyphenols from diet, gut microbiota and oxidative stress

Abstract

[Introduction]: Epidemiological studies have suggested an association between polyphenols intake and oxidative stress-related diseases. Information about the intake of polyphenols in human populations has been limited to the data available in nutrient databases, which do not include the food content of non-extractable polyphenols (NEPP). Recently, the information relative to these compounds in Spanish fruits and vegetables has been published. Thus, since they are associated with the insoluble food matrix and may reach completely intact the colon, these compounds are of special interest in the study of diet-microbiota interactions. [Objectives]: To analyse the intake of the total NEPP and their subclasses in a healthy adult population and to explore the relationship with the gut microbiota and oxidative stress biomarkers. [Methods]: This study involved 103 healthy adults. Dietary intake was assessed by an annual food frequency questionnaire. NEPP content data were extracted from Pérez-Jimémez et al. and dietary fiber content data from Marlet et al. Serum malondialdehyde (MDA) levels were determined and the major phylogenetic microbial types present in the gut quantified by qPCR. [Results]: NEPP represent a 73.64% of the total phenolic intake. From them, hydrolysable polyphenols, and non-extractable flavonols, hydroxybenzoic and hydroxycinnamic acids, were negatively associated with MDA. Non-extractable hydroxybenzoic acid was found to be an independent contributor to Bacteroides-Prevotella-Porphyromonas group levels (R2=0.053, β=0.230), whereas Clostridium cluster XVIa variation was explained by the intake of non-extractable flavonols and Klason lignin (R2=0.150, β=-0.318 and 0.297, respectively). Moreover, the levels of Lactobacillus group were associated with non-extractable flavonols intake (R2=0.095, β=-0.308). [Conclusions]: NEPP are associated with some of the major intestinal microbial groups and oxidative stress. Our data could be of great interest for future studies in order to elucidate the complex relation among diet-microbiota-health.