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We systematically review the in vivo preclinical evidence on the impact of microplastics (MPs) on the intestinal microbiota and morphofunctional changes involving the intestinal mucosa.By using a comprehensive and structured search in electronic databases 28 original studies were recovered and analyzed.Zebrafish and mice were the main animal models, while the dose and shape of MPs used were quite heterogeneous. Studies show that MPs are potential triggers of intestinal dysbiosis, which has been characterized by enrichment of Firmicutes, Proteobacteria and Chlamydia. Conversely, there was a reduction in Bacteroidetes phylum abundance. By trapping and stimulating intestinal inflammatory infiltrate, exposure to MPs increased intestinal permeability and the expression of immune signatures associated with inflammation, such as IL-1α, IL-1β, TNF-α, IFN-γ and IL-6.Thus, current evidence supports potential inflammatory and dysbiotic properties of MPs. In addition, the data indicate that MPs can display structural changes secondary to exposure to MPs. Analysis of methodological quality indicated that current preclinical evidence is at high risk of bias. We hope that controlling that bias sources described in this systematic review will be useful to improve the quality of reports.

The progressive decline in estrogen level puts postmenopausal women at a higher risk of developing cardiometabolic diseases. Thus, we evaluated the potential beneficial effects of yacon-based product (YBP) on glycemic profile and intestinal health of postmenopausal rats.Eighty Wistar rats were randomized into 4 ovariectomized (OVX) groups or 4 celiotomized groups treated with a standard diet (SD) or diet supplemented with YBP at 6% of fructooligosaccharide (FOS)/inulin.The continued consumption of YBP at 6% of FOS/inulin did not generate liver damage and gastrointestinal disorders. Rats fed with YBP displayed higher food consumption, but this did not increase the body weight gain, abdominal circumference and body fat percentual of OVX rats. Furthermore, we also found that the FOS/inulin fermentation present in the YBP resulted in cecum, ileum and colon crypts hypertrophy and increased the lactic acid levels in the cecal content. We observed an increase of glucagon-like peptide-1 (GLP-1) immunoreactive cells and there was no change in the glucose and insulin plasma levels of YBP-fed OVX rats.Our findings indicated that YBP when consumed previously and after the menopausal period has important effects on the morphology and function of intestinal mucous of rats and has potential to modulate indirectly the glycemic and insulinemic profiles, weight gain and body fat percentual in the hypoestrogenic period through metabolites produced in the fermentation process.