Specific dietary fibers prevent heavy metal disruption of the human gut microbiota in vitro.

Heavy metal exposure is a growing concern due to its adverse effects on human health, including the disruption of gut microbiota composition and function. Dietary fibers have been shown to positively impact the gut microbiota and could mitigate some of the heavy metal negative effects. This study aimed to investigate the effects of different heavy metals (As, Cd and Hg in different concentrations) on gut microbiota in the presence and absence of different dietary fibers that included fructooligosaccharides, pectin, resistant starch, and wheat bran. We observed that whereas heavy metals impaired fiber fermentation outcomes for some fiber types, the presence of fibers generally protected gut microbial communities from heavy metal-induced changes, especially for As and Cd. Notably, the protective effects varied depending on fiber types, and heavy metal type and concentration and were overall stronger for wheat bran and pectin than other fiber types. Our findings suggest that dietary fibers play a role in mitigating the adverse effects of heavy metal exposure on gut microbiota health and may have implications for the development of dietary interventions to reduce dysbiosis associated with heavy metal exposure. Moreover, fiber-type specific outcomes highlight the importance of evidence-based selection of prebiotic dietary fibers to mitigate heavy metal toxicity to the gut microbiota.

In vitro colonic fermentation and potential prebiotic properties of pre-digested jabuticaba (Myrciaria jaboticaba (Vell.) Berg) by-products.

Jabuticaba (Myrciaria jaboticaba (Vell.) Berg) by-products (JB) are rich sources of dietary fiber and phenolic compounds, which can be fermented by intestinal microbiota to promote health benefits. This study evaluated the effects of a 48 h-in vitro colonic fermentation of pre-digested JB on the contents of phenolic compounds and sugars, production of organic acids, and abundance (%) of bacterial groups found as part of the human intestinal microbiota. JB reduced the pH (4.35) and promoted changes on phenolic compounds (profile and contents) and sugars, as well as production of short-chain fatty acids during the fermentation. JB increased the abundance of Lactobacillus spp./Enterococcus spp. (4.32-6.25%) and Bifidobacterium spp. (4.60-10.03%) during the fermentation, and decreased the abundance of Bacteroides spp./Prevotella spp. (7.50-10.71%), Eubacterium rectale/Clostridium coccoides (1.37-3.70%), and C. histolyticum (0.91-2.30%), resulting in positive prebiotic indexes (8.61-11.92). JB should contribute to beneficial changes in the human intestinal microbiota, with effects compatible with prebiotic ingredients.

In Vitro Fecal Fermentation of High Pressure-Treated Fruit Peels Used as Dietary Fiber Sources.

Fruit by-products are being investigated as non-conventional alternative sources of dietary fiber (DF). High hydrostatic pressure (HHP) treatments have been used to modify DF content as well as its technological and physiological functionality. Orange, mango and prickly pear peels untreated (OU, MU and PPU) and HHP-treated at 600 MPa (OP/55 °C and 20 min, MP/22 °C and 10 min, PPP/55 °C and 10 min) were evaluated. Untreated and treated fruit peels were subjected to fecal in vitro fermentations. The neutral sugar composition and linkage glycosidic positions were related to the production of short chain fatty acids (SCFA) resulting from the fermentation of the materials. After HHP-treatments, changes from multibranched sugars to linear sugars were observed. After 24 h of fermentation, OP yielded the highest amount of SCFA followed by PPU and MP (389.4, 282.0 and 204.6 µmol/10 mg DF, respectively). HHP treatment increased the SCFA concentration of orange and mango peel by 7 and 10.3% respectively, compared with the untreated samples after 24 h of fermentation. The results presented herein suggest that fruit peels could be used as good fermentable fiber sources, because they yielded high amounts of SCFA during in vitro fermentations.