Aflatoxin B1

Aflatoxin B1 (AFB1) is the most toxic and carcinogenic of the aflatoxins, a group of mycotoxins produced by molds like Aspergillus flavus and Aspergillus parasiticus. These molds thrive in warm, humid environments and commonly contaminate crops such as peanuts, corn, cottonseed, tree nuts, and spices. 

AFB1 is highly potent, capable of causing acute toxicity with symptoms like liver failure and hemorrhaging, and chronic exposure significantly raises the risk of liver cancer by inducing DNA mutations. 

While one may test for AFB1 presence directly, a primary biomarker for assessing AFB1 exposure is Aflatoxin M1 (AFM1), a hydroxylated metabolite found in urine.  Other biomarkers include Aflatoxin-N7-guanine (AF-N7-Gua) adducts, which indicate DNA damage, and minor metabolites like Aflatoxin Q1 (AFQ1) and Aflatoxin P1 (AFP1), which reflect the body's detoxification processes. 

These biomarkers are crucial for evaluating both immediate and long-term health risks associated with AFB1 exposure.

What are Aflatoxins?  [9.] 

Aflatoxins are a group of highly toxic and carcinogenic compounds produced as secondary metabolites by certain molds, primarily Aspergillus flavus and Aspergillus parasiticus.  [9., 20.]

They are one type of mycotoxin, which are a larger group of toxic chemical compounds produced by molds.  

These mycotoxins are formed when the molds colonize foods like peanuts, corn, cottonseed, tree nuts, and spices under favorable temperature and humidity conditions.   [9., 19.] 

The main aflatoxins are B1, B2, G1, and G2, with aflatoxin B1 (AFB1) being the most potent and carcinogenic.  [3.] 

Their production occurs when the mold's growth is stressed, such as during drought conditions or improper crop storage. 

Aflatoxins are among the most carcinogenic substances known - they can cause acute toxicity leading to liver failure, hemorrhaging, and even death in severe cases.   [9.]  Chronic exposure increases the risk of developing liver cancer, as aflatoxins can bind to DNA and cause mutations, particularly in the p53 tumor suppressor gene. [9., 11.]

They can also suppress the immune system, and can cause stunted growth in children.  [10., 15., 16.]

Worryingly, aflatoxins are highly stable and can persist in foods and animal feeds even after processing and cooking.  They bioaccumulate in the body over time, especially in the liver, due to their lipophilic nature and resistance to metabolic breakdown.  [1., 12., 14.] 

Aflatoxin B1 is metabolized to the reactive aflatoxin-8,9-epoxide, which binds to DNA and proteins, initiating carcinogenesis.  [16.] 

Animals fed contaminated feed can pass aflatoxin metabolites into meat, milk, and eggs, posing risks to humans consuming these products.

Anti-Aflatoxin Biomarkers

Anti-aflatoxin biomarkers are a group of compounds or metabolites that can be measured in biological samples to assess exposure to aflatoxins, which are toxic and carcinogenic metabolites produced by certain molds. 

These biomarkers provide a direct measure of internal exposure and can help evaluate the associated health risks.

A variety of biomarkers have been used to identify the presence of aflatoxins in humans and animals.  

Aflatoxin B1, known as one of the most potent and toxic aflatoxins, is one such biomarker.  

Aflatoxin B1 Biomarkers  [8.]

Aflatoxin B1 (AFB1) may be tested directly in urine; additionally, other biomarkers of AFB1 exposure can also be measured in urine samples:

Aflatoxin M1 (AFM1) 

AFM1 is a hydroxylated metabolite of AFB1, found in the milk of mammals consuming AFB1-contaminated feed.  This metabolite of AFB1 is commonly measured in urine to indicate recent AFB1 exposure.

Aflatoxin-N7-guanine (AF-N7-Gua) Adducts

These are products formed by the binding of AFB1 metabolites to guanine in DNA, and can be measured in urine to assess the biologically effective dose of AFB1 exposure leading to DNA damage.  It plays a key role in the initiation of liver cancer.  

AF-N7-Gua is an important biomarker as it indicates direct genotoxic impact of aflatoxin exposure.

Aflatoxin Q1 (AFQ1) and Aflatoxin P1 (AFP1)

AFQ1 is a hydroxylated metabolite of AFB1 formed during detoxification processes in the liver.  AFP1 is another detoxification product of AFB1, formed through similar pathways as AFQ1.

While less toxic than AFB1, the presence of AFQ1 indicates exposure and the body's detoxification response to aflatoxin.

AFP1 detection is part of assessing the metabolic processing of aflatoxins in the body.

Aflatoxin B1-Lysine Adduct  [4.]

The Aflatoxin B1-lysine adduct is formed when the reactive AFB1 epoxide binds to the ε-amino group of lysine residues in serum albumin or other proteins.  This adduct can be detected in blood or urine samples and serves as a reliable indicator of recent AFB1 exposure. 

Aflatoxin Q1 (AFQ1) and aflatoxin P1 (AFP1)  [9., 20.]

These are minor metabolites of AFB1 that can be measured in urine as additional biomarkers of recent exposure.

Aflatoxin B1 Laboratory Testing Methods

Test Information, Sample Collection and Preparation

Various biological samples can be employed to detect and quantify anti-aflatoxin biomarkers, particularly blood, urine and nasal secretions.

Blood samples are typically collected via venipuncture in a clinical setting, while urine and nasal secretion samples may be collected from the comfort of home.  

It is important to consult with the ordering provider prior to sample collection, as certain protocols may be recommended beforehand.  

Interpretation of Aflatoxin B1 Test Results

Optimal Levels of Aflatoxin B1 Test Results

Because of the high level of toxicity of aflatoxin B1, optimal test results indicate undetectable levels of aflatoxin B1.  

Clinical Significance of Elevated Aflatoxin B1

Elevated levels of aflatoxin B1 indicate recent or current exposure to aflatoxins.  However, because they are known to bioaccumulate, testing positive for the presence of aflatoxins may indicate a persistent historical exposure.  [5., 6., 18.]

Clinical Significance of Low Aflatoxin B1

Low or undetectable levels of aflatoxin B1 are considered ideal.  

Aflatoxin B1 Related Biomarkers

In addition to the direct measurement of aflatoxin B1 biomarkers, other biomarkers can provide complementary information about aflatoxin exposure and its potential health effects.

Oxidative Stress Markers  [17., 21.]

Aflatoxin exposure is known to induce oxidative stress, which can lead to cellular damage and contribute to the development of various diseases. 

Biomarkers such as malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) can be measured to assess oxidative stress levels and the associated risk of aflatoxin-related toxicity.  [17.] 

Liver Function Markers  [7.] 

Since the liver is a primary target organ for aflatoxin toxicity, monitoring liver function biomarkers like alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin can provide insights into the extent of hepatic injury and potential liver damage caused by aflatoxin exposure.  

Inflammatory Biomarkers  [17.] 

Aflatoxin exposure can trigger inflammatory responses, and biomarkers such as C-reactive protein (CRP), interleukins (e.g., IL-6, IL-8), and tumor necrosis factor-alpha (TNF-α) can be measured to evaluate the inflammatory status and associated health risks.

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