Heavy metals (HMs) in the environment have become an increasingly common health risk in the last several decades. Gut microbiota (GM) are critical for intestinal homeostasis and involved in the absorption, metabolism and excretion of HMs. Recently, some studies have revealed that HMs exposure could lead to gut microbiota dysbiosis. Gut dysbiosis might result in gastrointestinal and immunological disorders, as well as malignancies. In this review, we discuss the possible effects of heavy metals on the GM and their subsequent effects on the gut.

The more recently published studies (2009–2019) searched in Cochrane Library, EMBASE, and MEDLINE for the articles that examined interaction of HMs with gut microbiota in CRC.

HMs exposure not only changes the GM community-level abundance but also at the function level, markedly disturbs its metabolic profiles. Furthermore, it may cause constant changes in the transport-related genes expression, the gut oxidative and inflammatory status and genotoxicity.

Review of evidence suggesting that while gut microbiom are a major element that must be considered for fully assessment the toxicity of heavy metals contaminants, yet underestimated factor in gut ecology. More researches are needed to realize the crosstalk between the environment, gut microbiota and gastrointestinal malignancies susceptibility.