Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This systematic review analyzed 54 animal studies investigating the protective roles of commensal gut microbiota, prebiotics, probiotics, and synbiotics against toxicities induced by environmental pollutants, with a significant focus on heavy metals. The review meticulously assessed the efficacy of these interventions in mitigating pollutant-induced oxidative stress, inflammation, and tissue damage, while also evaluating the quality and reliability of the included studies using the SYRCLE risk of bias tool and the ToxRTool. The primary goal was to synthesize evidence on how modulating the gut microbiome can counteract the adverse health effects of pollutants like cadmium, lead, mercury, and mycotoxins.
Who was reviewed?
The reviewed evidence was gathered exclusively from animal models, comprising 54 studies published between 1980 and 2023. The subjects included were rats (25 studies), mice (25 studies), and zebrafish (4 studies). These studies exposed the animals to various heavy metals such as cadmium, lead, mercury, and aluminum, as well as persistent organic pollutants and mycotoxins, and then administered interventions including specific probiotic strains like Lactobacillus plantarum and Bacillus coagulans, prebiotics like galactooligosaccharides and inulin, or synbiotics to evaluate their protective effects.
Most important findings
| Critical Point | Details |
|---|---|
| Reduced Heavy Metal Absorption | Probiotics and prebiotics consistently reduced the absorption of heavy metals like cadmium and lead in the intestine, leading to decreased accumulation in critical organs such as the liver and kidneys. |
| Increased Fecal Excretion | Interventions enhanced the fecal excretion of pollutants. For instance, specific probiotic strains and the prebiotic galactooligosaccharide significantly increased the fecal output of lead and cadmium. |
| Enhanced Antioxidant Defenses | Supplementation was linked to increased activity of antioxidant enzymes like superoxide dismutase (SOD) and glutathione (GSH), and a reduction in oxidative stress markers such as malondialdehyde (MDA). |
| Improved Gut Barrier Integrity | Probiotics and prebiotics were shown to strengthen the intestinal barrier by supporting tight junction proteins, thereby reducing gut permeability (“leaky gut”) and limiting the systemic absorption of pollutants. |
| Anti-Inflammatory Effects | The interventions downregulated pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and interleukins (IL-1β, IL-6), alleviating pollutant-induced inflammation in various tissues. |
| Mechanism of Sequestration | A key protective mechanism identified was the direct binding or sequestration of heavy metals to the cell walls of probiotic bacteria and prebiotic fibers, facilitating their removal from the body. |
Key implications
The findings have primary regulatory impacts by validating gut microbiome modulation as a legitimate mechanistic pathway for mitigating heavy metal toxicity, which could inform safety assessments and health claim approvals. For certification requirements, this underscores the need to verify specific probiotic strains and prebiotic efficacy in binding and excreting heavy metals. Industry applications include developing functional foods or supplements for at-risk populations. Significant research gaps remain in human trials and standardizing interventions. Practical recommendations involve prioritizing specific, studied strains and incorporating gut health biomarkers into monitoring programs for occupational exposures.
Citation
Zarezadeh M, Saedisomeolia A, Mahmoudinezhad M, Iskandar MM, Lu F, Kubow S. Protective Roles of Prebiotics and Probiotics Against Environmental Pollutant-Induced Toxicities: A Systematic Review of Animal Studies.Mol Nutr Food Res. 2025;0:e70175. https://doi.org/10.1002/mnfr.70175
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
