Aflatoxin

Overview

Aflatoxins are toxic secondary metabolites produced primarily by Aspergillus flavus and Aspergillus parasiticus that contaminate food crops such as maize and groundnuts, particularly under warm, humid conditions and poor storage.^[1] Aflatoxin B1 (AFB1) is the most potent member of this group and is strongly linked to hepatocellular carcinoma through well-established human and mechanistic evidence.^[2] Chronic dietary exposure is a major global health issue because aflatoxins can enter the gut–liver axis, where intestinal absorption determines internal dose and clinical risk.^[3]

Mechanism of toxicity and carcinogenesis

AFB1 becomes highly carcinogenic after metabolic activation by hepatic cytochrome P450 enzymes, generating an AFB1-8,9-epoxide that forms DNA adducts, particularly at guanine bases.^[4] These adducts can cause characteristic mutations and drive malignant transformation in liver tissue, especially with long-term exposure.^[5] Epidemiologic analyses demonstrate that aflatoxin exposure substantially increases liver cancer risk and acts synergistically with hepatitis B infection, magnifying population-level disease burden.^[6]

Microbiome disruption and gut–liver signaling

Aflatoxin is increasingly relevant in microbiome medicine because it can disrupt microbial metabolism and intestinal barrier signaling. In a controlled rodent study, oral AFB1 exposure caused significant alterations in gut microbiota–dependent metabolic pathways, including changes in short-chain fatty acids and bile acid–related metabolites, which are key regulators of mucosal immunity and gut–liver communication.^[7] These metabolomic disruptions support a mechanistic pathway in which aflatoxin exposure may promote inflammation and impaired barrier function through microbiome-mediated processes.^[8]

Microbial interactions are also clinically important because gut organisms can bind or transform aflatoxin, altering effective exposure. Experimental work has shown that probiotic strains can reduce aflatoxin burden via binding and biotransformation, providing a biologically plausible strategy to lower intestinal toxin availability.^[9] In one study, a probiotic microorganism demonstrated measurable detoxification activity against AFB1 under controlled conditions, supporting the concept that microbiome functions can modify toxin risk.^[10]

Clinical interpretation in microbiome medicine

In microbiome-focused care, aflatoxin exposure should be considered in patients with dietary risk factors, unexplained liver injury, immune dysfunction, or persistent inflammatory symptoms.^[11] Biomarkers such as aflatoxin–albumin adducts and urinary aflatoxin metabolites support objective exposure assessment and help stratify risk in high-exposure settings.^[12] Microbiome evaluation adds value by identifying disrupted microbial metabolic signatures and barrier-related patterns that may amplify toxin effects, particularly in chronic exposure.^[13]

Update History

References

1. Aflatoxins and growth impairment: A review.. Khlangwiset P, Shephard GS, Wu F.. (Critical Reviews in Toxicology. 2011)
2. Mycotoxins and human disease: a largely ignored global health issue. Wild CP, Gong YY.. (Carcinogenesis. 2010)
3. Aflatoxins and growth impairment: A review.. Khlangwiset P, Shephard GS, Wu F.. (Critical Reviews in Toxicology. 2011)
4. Activation and detoxication of aflatoxin B1. Guengerich FP, Johnson WW, Shimada T, Ueng YF, Yamazaki H, Langouët S.. (Mutation Research. 1998)
5. Activation and detoxication of aflatoxin B1. Guengerich FP, Johnson WW, Shimada T, Ueng YF, Yamazaki H, Langouët S.. (Mutation Research. 1998)
6. Mycotoxins and human disease: a largely ignored global health issue. Wild CP, Gong YY.. (Carcinogenesis. 2010)
7. Assessment of the adverse impacts of aflatoxin B1 on gut-microbiota dependent metabolism in F344 rats. Zhou J, Tang L, Wang J-S.. (Chemosphere. 2019)
8. Assessment of the adverse impacts of aflatoxin B1 on gut-microbiota dependent metabolism in F344 rats. Zhou J, Tang L, Wang J-S.. (Chemosphere. 2019)
9. Detoxification of Aflatoxin B1 by a Potential Probiotic Bacillus amyloliquefaciens WF2020. Chen G, Fang Q, Liao Z, et al.. (Frontiers in Microbiology. 2022)
10. Detoxification of Aflatoxin B1 by a Potential Probiotic Bacillus amyloliquefaciens WF2020. Chen G, Fang Q, Liao Z, et al.. (Frontiers in Microbiology. 2022)
11. Aflatoxins and growth impairment: A review.. Khlangwiset P, Shephard GS, Wu F.. (Critical Reviews in Toxicology. 2011)
12. Mycotoxins and human disease: a largely ignored global health issue. Wild CP, Gong YY.. (Carcinogenesis. 2010)
13. Assessment of the adverse impacts of aflatoxin B1 on gut-microbiota dependent metabolism in F344 rats. Zhou J, Tang L, Wang J-S.. (Chemosphere. 2019)