Table 4.
Adverse health effect of heavy metals in inflammatory bowel disease.
| Contaminant | References | Experiment model/human group | Exposure time/dose | Route of exposure | Source of dietary intake | Impact on the gut | Other health risks |
|---|---|---|---|---|---|---|---|
| Lead | Yu et al. (11) | C57BL/6 mouse models | 0.1, 0.5, and 1.0 g/L for 8 weeks | Dietary exposure | Drinking water | °↓ Expression of tight junction proteins °↑ Abundance of Marvinbryantia and Ruminococcus °↓Abundance of Lactobacillus and Roseburia ° Induce gut dysbiosis | ° Influence the metabolism of macronutrients, trace elements ° Neurodegenerative injury ° Inhibit CAT activity in kidney and GSH level in liver |
| Xia et al. (109) | Male adult wide type AB strain zebrafish (Danio rerio) | Respective 10 and 30 μg/L for 7 days | / | / | °↑ Gut mucus volume °↓The abundance of α-Proteobacteria °↑ The abundance of Firmicutes | ° Induce hepatic metabolic disorder | |
| Manganese | Choi et al. (110) | Wild type C57BL/6 mice aged 3–4 weeks | Mn: 0–0.5 ppm (deficient), 35–35.5 ppm (adequate), and 300-301 ppm (supplemented). | Dietary exposure | Diets | ° Maintain the intestinal barrier °↑ Morbidity, weight loss, and colon damage °↑ Levels of inflammatory cytokines | / |
| Mitchell et al. (111) | Male C57BL/6 mice | MnCl2 (66 mg/kg) | i.p. injection | / | ° Reduce chronic colitis | / | |
| Arsenic | Zhong et al. (112) | 1-day-old ducks | control group; low ATO group 4 mg/kg; high ATO group 8 mg/kg. | Oral administration and intubation | Drinking water | ° Intestinal injury °↓α diversity of intestinal flora ° Change bacterial composition °↓ Expression of intestinal barrier related proteins | ° Liver inflammatory cell infiltration ° Vesicle steatosis °↑ Pro-inflammatory CKs (IFN-γ TNF-α IL-18 and IL-1β) in the liver |
| Cadmium | Breton et al. (113) | 12-week-old female BALB/c mice | CdCl2 (2.5 and 12.5 mg/kg) for 1, 4, or 6 weeks | Dietary exposure | Drinking water | °↓ Epithelial permeability °↑ Oxidative defense mechanism °↓ Nf-κB and pro-inflammatory cytokine pathways ° Stimulate anti-oxidant pathways | / |
| Mercury | Zhao et al. (114) | Female Kunming mice | 80 mg/L HgCl2 for 90 days | Dietary exposure | Drinking water | ↑ Faecalis, Helicobacter °↓ Halococcus and Bacillus ° intestinal injury | ↑ Pro-apoptotic gene expression |
| Zhao et al. (115) | Eight-week-old female mice | HgCl2 (160 mg/L) for 3 days | Dietary intake | Drinking water | ↓ Growth performance ° Induce oxidative stress °↑ Clostridium, Lactobacillus | / | |
| Seki et al. (116) | Female C57BL/6 mice | MeHg (5 mg/kg) for 14 days | Oral intubation | / | ° Inhibit the growth of lactobacillus | °↓ Gut bacteria after exposure to methylmercury ° Accelerated accumulation in the cerebellum, liver, and lungs |
“↑” means increased level or concentration; “↓” means decreased level or concentration.