Mold toxins (mycotoxins) have received much attention from the functional medicine community in recent years. However, few practitioners take time to distinguish between the various individual mycotoxins, and choose instead to treat all mycotoxins as one in the same. This shotgun approach to dealing with mold poisoning (mycotoxicity) is unacceptable and lacks the nuance necessary for delivering quality healthcare. For this reason, I have decided to dedicate a handful of blog posts to tease apart the most common mycotoxins that may be causing problems, and what can be done to lower exposure and improve elimination.
So, what are aflatoxins? Aflatoxins are a class of mycotoxins produced from Aspergillus mold species, particularly Aspergillus flavus and parasiticus. There are five main aflatoxins (B1, B2, G1, G2, M1), with aflatoxin B1 and M1 being class 1 and 2B carcinogens respectively. Both acute and chronic exposure to aflatoxins increase the risk of hepatocellular carcinoma, with sublethal chronic exposure being associated with immune dysregulation, nutrient malabsorption, and other metabolic disorders.
Aflatoxins 101
Aflatoxins are a subcategory of mycotoxins that are produced from the genus of mold, Aspergillus.1 Specifically, aflatoxins are produced by Aspergillus flavus and parasiticus species. There are five different aflatoxins, called aflatoxinB1, aflatoxinB2, aflatoxinG1, aflatoxinG2, and aflatoxinM1. The names suggest the color of the toxins when exposed to ultraviolet light (B = blue, G = green, M = found in milk).2 AflatoxinB1 and aflatoxinM1 are the two most toxic aflatoxins.3
Aflatoxins are most commonly found in foods and oral ingestion is the most common route of toxicity in humans. Foods particularly high in aflatoxins include corn, peanuts, meat, and dairy products. Corn, peanuts, and meat tend to be sources of aflatoxinB1, whereas dairy products contain aflatoxinM1.4
Since aflatoxins account for the majority of mycotoxicity in the food supply, both the FDA and European Union have strict regulations on the amount of aflatoxins allowed to be in certain food products.5 The FDA allows 20 parts per billion of aflatoxin in foods (peanuts, corn, pistachios, etc,) and only 0.5 parts per billion in milk.6 Cheese may still be of concern since milk products, including aflatoxinM1, are concentrated during production. Concentration and safety of aflatoxin in cheese is still being researched.7
Metabolism of Aflatoxin
As stated previously, oral ingestion is the main route of toxicity with aflatoxins. Aflatoxins are absorbed into the bloodstream once consumed. About 65% of aflatoxins will be eliminated through the bile duct within 90 minutes of ingestion.8 This detoxification process is carried out by the liver where the majority of aflatoxin accumulates. Aflatoxin accumulates in the kidneys and spleen to lesser degrees.9 The liver must convert aflatoxin into a more water-soluble form in order to be eliminated through the bile. In order to do this, the liver transforms aflatoxin into water-soluble metabolites. It is these metabolites that are particularly harmful to the body. In order to protect the body from these toxic metabolites, the liver additionally buffers the aflatoxin with special molecules to stop them from causing DNA damage. This process is known as conjugation and requires glutathione, glucuronic acid, or sulfate.10
Once aflatoxin is neutralized through conjugation, it is eliminated from the liver via the bile duct. Once in the GI tract, it is eliminated via a bowel movement. It is possible for aflatoxin to be reabsorbed into the bloodstream through a process called enterohepatic reabsorption. This process is dependent on an individual’s microbiome, fiber intake, and bowel movement frequency. This phenomenon is not well studied in aflatoxin toxicity.
Toxicity of Aflatoxin
Aflatoxins are incredibly toxic, with aflatoxinB1 being 68 times more toxic than arsenic.11 Aflatoxin is a group 1A carcinogen, meaning that it is known to cause cancer in humans. Specifically, aflatoxinB1 causes liver cancer, known as hepatocellular carcinoma.12 Aflatoxin is thought to play a causative role in 4.6-28.2% of all liver cancer cases worldwide, especially in countries where aflatoxin content in food is not regulated. 13
As stated previously, it is the partially detoxified metabolite of aflatoxinB1 known as AFBO (aflatoxinB1-8-9-epoxide) that causes the majority of liver damage. AFBO is extremely toxic and binds directly to DNA to form DNA adducts. These DNA adducts are the mutations that eventually can lead to cancer. 14
AFBO is also capable of escaping into systemic circulation where it can cause tissue damage, inflammation, and cancers in distal regions of the body by mutating DNA through adducts. AFBO can also cause cancer by turning off an important gene called p53. This gene is meant to suppress tumor formation. Under the epigenetic influence of AFBO, p53 can become silenced and unable to stop early tumor formation.15
Beyond cancer, aflatoxin has also been shown to have toxic effects in the GI tract, nervous system, immune cells, and reproductive organs. Though there is limited human data, aflatoxin has been shown to disrupt intestinal barrier health, alter microbiome balance, lead to intestinal inflammation, and cause nutrient malabsorption in animals.16 Similarly, aflatoxin has been shown to cause neurological damage in animal studies, increasing susceptibility to neurodegenerative diseases like Alzheimer’s disease.17 Both human and animal research has found aflatoxin to significantly suppress the immune system through the disruption of both the innate and adaptive branches. Aflatoxin also directly damages the thymus gland and spleen, which are important parts of the immune system. 18
Symptoms of Aflatoxin Exposure
Symptoms of aflatoxicosis are divided between acute and chronic exposure. Acute aflatoxicosis is very serious and results from oral ingestion of foods with very high levels of aflatoxins. Chronic symptoms result from long term sublethal ingestion of aflatoxin contaminated foods. 19
Acute Exposure Signs/Symptoms20
- Nausea
- Yellowing of skin and sclera (icterus)
- Itching
- Vomiting
- Bleeding
- Abdominal pain
- Lethargy
- Edema
- Convulsions
- Coma
- Death
Chronic Exposure Signs/Symptoms212223
- Impaired growth and development, especially in children
- Immunosuppression
- Hepatocellular carcinoma (weight loss, abdominal mass, anorexia, vomiting, nausea, bleeding, psychosis, etc.)
- Malabsorption of certain nutrients (namely Vitamin A, and zinc)
- Insulin resistance
- Diabetes mellitus
Weight Gain and Aflatoxicosis
There is no recognized connection between aflatoxicosis and weight gain. Actually, aflatoxins are much more likely to cause weight loss in exposed individuals. However, a theoretical connection between aflatoxicosis and weight gain does exist.
Aflatoxin exposure is known to contribute towards liver disease. Of note, increased aflatoxin levels in the bloodstream are shown to be associated with diabetes. Though the mechanism is not fully elucidated, it is likely through direct tissue damage within the liver and pancreas24. Therefore, diabetes, second to aflatoxin exposure, may be a route through which aflatoxicosis may lead to weight gain. This can be confirmed through standard metabolic tests (HbA1c, fasting blood sugar, fasting insulin, c-peptide, etc.).
The clinical relevance of this association would be to screen high-risk diabetic individuals for aflatoxin exposure. These would be individuals who consume food from countries without aflatoxin screening procedures, those with liver abnormalities, and farmers.
Screening
Though there are no official guidelines for screening aflatoxin exposure, here are my thoughts.
Food Frequency Questionnaire
The foods most commonly contaminated with aflatoxin include peanuts, peanut butter, corn, tree nuts such as Brazil nuts and pistachios, small grains such as rice, meat, and dairy products.25
Individuals that report consuming these foods regularly may be more susceptible to aflatoxicosis. Individuals should check the country of origin, since not all countries and imports are screened for aflatoxin.
Occupational Exposure
Farmers and grain workers are at a higher occupational risk of aflatoxin exposure. Clinical suspicion should be heightened in these individuals.26
Testing Options
There are currently no FDA approved tests for identifying aflatoxin levels in humans. However, there are some testing options available that may have some clinical utility for identifying aflatoxicosis
Blood Testing
Aflatoxin albumin adducts: This test looks at the amount of albumin (a protein in the blood) that has been attacked by aflatoxins. It is considered a longer-term marker of aflatoxin exposure. However, this testing option is only available experimentally, and not direct to consumer or medical provider.
Antibody testing: This test looks for antibodies against various mycotoxins. Though it is purported to detect the pathogenicity (disease-causing aspect) of a given mycotoxin, there have been no studies proving this. Mycotoxin antibody testing is not FDA approved. For this reason, antibody testing of mycotoxins should be avoided.
Urine Testing
Metabolite testing: Most mycotoxin tests on the market come in the form of at-home urine tests. These tests evaluate the level of various mycotoxins and their metabolites in the urine. However, these tests are not FDA approved and have not proven any level for which significant exposure has occurred or when disease risk may be elevated. For this reason, urine testing of mycotoxins should be avoided.
Exposure Reduction Techniques
Aflatoxins can be avoided through proper sourcing of high-risk foods. It is best to source foods like peanuts, peanut butter, corn, tree nuts such as Brazil nuts and pistachios, small grains such as rice, meat, and dairy products from the US where the FDA ensures aflatoxin screening measures.27 Imported nuts, nut butters, and other products are not consistently screened for aflatoxin content. To date (2024), there has never been an aflatoxin outbreak in the US.28
Farmers and grain workers who have high occupational exposure to aflatoxins may choose to work with respirators and gloves to avoid exposure through inhalation and transdermal absorption respectively.
Detoxification Techniques
There are no validated treatments for aflatoxicosis. Instead, treatment is dependent on avoiding continuous exposure to aflatoxins and supporting general health. For this reason, a general functional detoxification protocol may be utilized to support biotransformation, antioxidant capacity, and elimination.
Specific nutraceuticals shown to enhance aflatoxin detoxification include:
Glutathione: Glutathione is an antioxidant used to conjugate aflatoxin as described in the metabolism section of this article. Glutathione can be supplemented orally or through liposomal forms. Glutathione is most commonly supplement through administration of oral N-acetylcysteine (NAC). Studies have shown NAC to protect the body from aflatoxicosis in bird models. 29
Milk Thistle: Extracts of milk thistle containing the active ingredient, silymarin, have profound anti-inflammatory and antioxidant effects in the liver. Supplementation of milk thistle has been shown to protect liver cells against aflatoxin in birds.30
Probiotics: Lactobacillaceae and Saccharomyces are both capable of binding to and absorbing aflatoxin in the digestive tract, preventing absorption into the bloodstream.31 Therefore, supplementation of these probiotics may serve as a means of reducing the impact of aflatoxin consumption.
Binders: Certain clays, fibers, and other absorptive compounds can bind various mycotoxins, including aflatoxin, in the digestive tract, preventing absorption into the bloodstream.32 However, these binders are also capable of binding numerous nutrients in the digestive tract which make them unfit for consumption alongside food.
Conclusion
Aflatoxins are a serious and potently carcinogenic class of mycotoxins. Though acute, clinically-relevant aflatoxicosis is rare in the US, there still may be risk to consuming sublethal levels in either imported or otherwise contaminated foods. As it stands, there is no FDA approved method for testing, and all direct-to-consumer testing methods have yet to be validated. For this reason, the best advice is for individuals to avoid overt exposure to high aflatoxin sources, support overall wellbeing, and for those with known exposure to be monitored for liver disease as exposure increases risk for liver cancer. Otherwise, aflatoxicosis is an unlikely cause for generic symptoms within the developed world.
- https://www.foodriskmanagement.com/wp-content/uploads/2013/03/Romer-Labs-Guide-to-Mycotoxin-Book_Original_41686.pdf ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9357370/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9357370/ ↩︎
- https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/aflatoxins#:~:text=Aflatoxins%20are%20a%20family%20of,humid%20regions%20of%20the%20world
↩︎ - https://www.foodriskmanagement.com/wp-content/uploads/2013/03/Romer-Labs-Guide-to-Mycotoxin-Book_Original_41686.pdf ↩︎
- https://www.foodriskmanagement.com/wp-content/uploads/2013/03/Romer-Labs-Guide-to-Mycotoxin-Book_Original_41686.pdf ↩︎
- https://www.sciencedirect.com/science/article/pii/B9780124170124000235 ↩︎
- https://www.sciencedirect.com/science/article/pii/B0123694000000296
↩︎ - https://www.sciencedirect.com/science/article/pii/B9780444522726002944 ↩︎
- https://www.sciencedirect.com/science/article/pii/B0123694000000296 ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9357370/ ↩︎
- https://pubmed.ncbi.nlm.nih.gov/34930097/ ↩︎
- https://ehp.niehs.nih.gov/doi/10.1289/ehp.0901388#:~:text=Of%20the%20550%2C000%E2%80%93600%2C000%20new,uncontrolled%20aflatoxin%20exposure%20in%20food
↩︎ - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9357370/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9357370/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4915736/#:~:text=They%20speculated%20that%20aflatoxin%20exposure%20may%20lead,at%20harvest%20children%20in%20the%20highest%20aflatoxin ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9357370/
↩︎ - https://openresearchafrica.org/articles/6-22#:~:text=Aflatoxin%20B1%20(AFB1)%2C%20a,thereby%20lead%20to%20secondary%20infections ↩︎
- https://www.ncbi.nlm.nih.gov/books/NBK557781/ ↩︎
- https://www.ncbi.nlm.nih.gov/books/NBK557781/
↩︎ - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8865065/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4915736/#:~:text=They%20speculated%20that%20aflatoxin%20exposure%20may%20lead,at%20harvest%20children%20in%20the%20highest%20aflatoxin ↩︎
- https://www.ncbi.nlm.nih.gov/books/NBK557781/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8919319/#:~:text=Increased%20environmental%20pollution%20and%20unhealthy,without%20aflatoxin%20administration%20in%20rats ↩︎
- https://www.fda.gov/food/natural-toxins-food/mycotoxins#:~:text=The%20foods%20most%20susceptible%20to,eat%20aflatoxin%20B1%20contaminated%20crops. ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090888/#:~:text=Aflatoxins%20were%20detected%20in%2032.6,workers%20had%20chronic%20respiratory%20symptoms ↩︎
- https://www.foodriskmanagement.com/wp-content/uploads/2013/03/Romer-Labs-Guide-to-Mycotoxin-Book_Original_41686.pdf ↩︎
- https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/aflatoxins#:~:text=Aflatoxins%20are%20a%20family%20of,humid%20regions%20of%20the%20world ↩︎
- https://pubmed.ncbi.nlm.nih.gov/11441839/#:~:text=N%2Dacetylcysteine%20(NAC)%20has,including%20aflatoxin%20B1%20(AFB1) ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3872588/#:~:text=Silymarin%2C%20an%20extract%20from%20the,B1%20(AFB1) ↩︎
- https://pubmed.ncbi.nlm.nih.gov/30454686/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6989347/#:~:text=Previously%20a%20calcium%20bentonite%20clay,for%20human%20and%20animal%20consumption ↩︎
Justin Perr is a Registered Dietitian and Certified Functional Medicine Practitioner specializing in weight loss and gut health. He helps patients uncover root causes and achieve lasting results with science-backed nutrition.
