Aflatoxins are the poisonous substances produced by the molds called Aspergillus, which contaminate the crops during production, harvest or storage and are associated with the increased risk of developing liver diseases.
Aflatoxins are the poisonous substances produced by the fungi such as Aspergillus flavus and Aspergillus parasiticus. These fungi grow in soil, hay, decaying plants, and grains and are found in the improperly stored crops such as corn, maize, spices, peanuts, rice, wheat, walnuts, pistachios, sunflower seeds, coffee, etc. all over the world with about 25% of world’s crop destroyed annually. However, these molds are more common in tropical and sub-tropical climates.
Aflatoxins have carcinogenic properties – exposure to these toxins are strongly associated with the increased risk of experiencing liver failure and/or developing liver cancer. In general, these substances may cause both acute and chronic liver damage. It was estimated that about 4.5 billion people who live in developing countries may be chronically exposed to aflatoxins.
Aspergillus is the species of ubiquitous spore-forming fungi. Among the hundreds of Aspergillus species, A.flavus and A.parasiticus are the most important as they produce mycotoxins known as aflatoxins, exposure to which may damage a person’s liver and increase the risk of developing primary liver cancer. However, their growth and toxin production requires a humid environment. Drought stress and insect damage may also be related to a higher occurrence of the fungal infection. In a moist environment, these molds are able to colonize and contaminate products before the harvest or when they are kept in storages.
Types of aflatoxins
Aspergillus species produce about 14 different aflatoxins, although only four of them (B1, B2, G1, and G2) are dangerous for humans.
- Aflatoxin B1 and B2, produced by Aspergillus flavus and A. parasiticus are the most common types of aflatoxins, aflatoxin B1 is considered the most potent hepatocarcinogen;
- Aflatoxin G1 and G2, produced by Group II A. flavus and Aspergillus parasiticus;
- Aflatoxin M1, a major metabolite of aflatoxin B1 in humans and animals which may be consumed with a mother’s milk;
- Aflatoxin M2, a metabolite of aflatoxin B2 in the milk of cattle fed on contaminated foods;
- Aflatoxin Q1 (AFQ1), metabolite of AFB1 in vitro liver preparations;
Some products are especially prone to fungal contamination and, therefore, when stored improperly, may pose the risk for people who consume such food.
- Peanuts, peanut butter;
- Ground and tree nuts (walnuts, pistachios, Brazil nut);
- Seeds (cottonseed, sunflower seeds);
Except for eating contaminated food, people may be exposed to aflatoxins by consuming dairy products, eggs or meat from animals that were fed with aflatoxin-contaminated feed. Those who are working with stored foods, crops, may inhale the dust containing aflatoxins.
In developed countries mean aflatoxin exposure is then 1 ng/kg body weight a day, whereas in less developed countries the levels may be much higher.
Acute poisoning (aflatoxicosis)
It is suggested that adults, in general, are not susceptible to acute aflatoxin exposure, although children may be affected the exposure exceeds 1 mg/kg – acute poisoning in children may cause acute hepatic necrosis and liver failure which manifests with jaundice, nausea, and lethargy.
Aflatoxins may have a cumulative effect when consumed in tiny amounts for a long period of time characterized by gut dysfunction, loss of appetite, growth retardation and decreased fertility.
Aflatoxin B1 is considered the most potent hepatocarcinogen, especially when a person is simultaneously exposed to viral hepatitis B. In such cases aflatoxin and HBV work synergically and increase the risk of developing hepatocellular carcinoma even more drastically.
Aflatoxins may cause immunosuppression and cause the decrease in the body’s resistance to infections, worsen the course of HIV-infection and increase a person’s susceptibility to tuberculosis.
- Before consuming any grains or nuts inspect them for any evidence of molds, avoid eating any that look suspicious.
- Fresh nuts and grains should be preferred.
- The crops should be stored properly, in dry storages for only a limited period of time.
- It is recommended to avoid eating broken nuts as they are more likely to be contaminated with aflatoxins.
- Diverse diet helps to reduce aflatoxin exposure and their influence on the body. Apiaceous vegetables such as carrots, parsnips, celery, and parsley are known to reduce the toxic influence of aflatoxins on the liver.