Abstract
Walnuts are rich in polyphenols ellagitannins, modulate gut microbiota (GM), and exert health benefits after long-term consumption. The metabolism of ellagitannins to urolithins via GM depends on urolithin metabotypes (UM-A, -B, or -0), which have been reported to predict host responsiveness to a polyphenol-rich intervention. This study aims to assess whether UMs were associated with differential GM modulation after short-term walnut consumption. In this study, 27 healthy individuals consumed 33 g of peeled raw walnuts over three days. GM profiling was determined using 16S rRNA illumina sequencing and specific real-time quantitative polymerase chain reactions (qPCRs), as well as microbial activity using short-chain fatty acids analysis in stool samples. UMs stratification of volunteers was assessed using ultra performance liquid chromatography–electro spray ionization–quadrupole time of flight–mass spectrometry (UPLC-ESI-QTOF-MS) analysis of urolithins in urine samples. The gut microbiota associated with UM-B was more sensitive to the walnut intervention. Blautia, Bifidobacterium, and members of the Coriobacteriaceae family, including Gordonibacter, increased exclusively in UM-B subjects, while some members of the Lachnospiraceae family decreased in UM-A individuals. Coprococcus and Collinsella increased in both UMs and higher acetate and propionate production resulted after walnuts intake. Our results show that walnuts consumption after only three days modulates GM in a urolithin metabotype-depending manner and increases the production of short-chain fatty acids (SCFA).
Highlights
Nuts are a significant source of macronutrients, micronutrients, and bioactive compounds
The analysis of urolithins in urine after three days of walnut consumption was used for clustering the individuals according to their urolithin metabotypes (UMs): UM-A (n = 14), UM-B (n = 13), and UM-0 (n = 0)
Understanding individuals’ response to dietary bioactive compounds such as polyphenols is response to dietary bioactive compounds such as gut polyphenols is essential in the context of personalized nutrition
Summary
Nuts are a significant source of macronutrients (e.g., proteins, unsaturated fats, polysaccharides, fiber), micronutrients (e.g., vitamins and minerals), and bioactive compounds (e.g., tocopherols, phytosterols, phenolic compounds [1]). Epidemiologic studies have associated long-term nut consumption with a reduced incidence of coronary heart disease, hypertension, and cholesterol-lowering effect [4]. Nutrients 2019, 11, 2483 effects of nut consumption may be linked to gut microbiota, which can release bioactive compounds with higher bioavailability and functionality than parental compounds [5]. Several studies have demonstrated changes in gut microbial communities after the intake of ETs-containing foods on week timescale [2,6,7,8,9,10]. Some of these studies revealed a personalized effect of foods containing
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