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The impact of mycotoxins on human health

Author: Athanasios Patsiogiannis, Alltech Business Insights Co-ordinator

Food and agricultural products are naturally contaminated with mycotoxins. However, the accumulation of mycotoxins in feed and food is a common and serious problem causing many acute and chronic health problems in both animals and humans worldwide. According to John and Miller (2017), mycotoxins have caused epidemics in both humans and animals. One of these, the ergotism breakout in Europe, killed hundreds of thousands of people in the last millennium. Mycotoxins were also found to be responsible for alimentary toxic aleukia, which lead to similar numbers of deaths in Russia between 1942 and 1948. Many illnesses can be attributed to mycotoxins, such as headaches and various gastrointestinal issues, including abdominal pain, vomiting, and diarrhea (WHO and FAO, 2011).

A recent issue of All About Feed (Volume 28, No.1, 2020) also stated that the risk to human health and food security from mycotoxins might be greater in Asia due to climate change (elevated C02 levels, changing temperatures and weather events). These environmental issues could lead to staple crops, such as rice and maize, being contaminated to a higher extent, and their production, as well as nutritional quality, being compromised. Seeing as Asia is highly dependent on these crops, food security will be at risk.

The most prevalent mycotoxins are aflatoxins, ochratoxin A, citrinin, patulin, trichothecenes (deoxynivalenol, T2 toxin, HT2 toxin), fumonisins and zearalenone. These are produced by toxigenic fungi such as Aspergillus, Fusarium, Penicillium, and Alternaria, which can create one or more mycotoxins (Darwish et al., 2014). For instance, more than one fungal species can produce aflatoxins and ochratoxins. This inevitably adds to the constant presence of mycotoxins.

Some of the abovementioned mycotoxins have been classified by the World Health Organization (WHO) as human carcinogens. Mycotoxins are grouped into mutagenic, carcinogenic, or teratogenic categories, depending on their toxic activity under chronic conditions. For example, aflatoxins are classified as human carcinogens and ochratoxins and fumonisin are seen as possible human carcinogens. However, trichothecenes and zearalenone are not recognized as human carcinogens (WHO, 1993).

Health issues related to most known mycotoxins

The adverse effects of mycotoxins in humans and animals vary among the different strains. Upon ingestion, inhalation or absorption through the skin, aflatoxins have carcinogenic, hepatotoxic, teratogenic, and mutagenic effects on human health, even at low levels (Wen et al., 2014). Looking at recent history, aflatoxins were the cause of the aflatoxicosis breakouts back in 1981, 2001, 2004, and 2005 in Kenya. Among all aflatoxins, AFB1 is the most potent and is proven to be hepatotoxic and hepatocarcinogenic (Makun et al., 2011). In 2004, 123 people in the eastern province of Kenya died due to exposure to aflatoxins (Nyaga, 2010). On top of this, AFB1 can also be converted into another toxic metabolite. When dairy ruminants consume feeds contaminated with AFB1, this toxin is metabolized, and AFM1 is excreted in milk. This particular metabolite is also carcinogenic. Ochratoxin is associated with a high risk of nephropathy in humans. There is evidence that this mycotoxin is the leading cause of Tunisian nephropathy and human Balkan endemic nephropathy (Malir et al., 2012). Moreover, its teratogenic effect is well reported (Soleas et al., 2001). Fumonisin has also been associated with cancer of the esophagus in humans (Shephard, 2011), although it seems to affect animals differently (i.e., leukoencephalomalacia in equine and rabbits).

On the other hand, other mycotoxins have different effects, more related to metabolic processes in the body. For example, trichothecenes inhibit protein synthesis, harming the health of their host (Zinedine and Manes, 2009). Zearalenone is known for its adverse effect on hormonal balance and reproduction. It mimics natural estrogens (i.e., 17β-estradiol) and, as a result, binds estrogen receptors, impairing the hormonal balance and leading to myriad reproductive system diseases (Kowalska et al., 2018).

Provide support by managing mycotoxins

Inevitably, mycotoxins are an integral part of the food chain. Monitoring and controlling them in all stages of the chain is crucial to ensuring minimum exposure to humans and animals. The industry is responding and continually seeking better ways to address the issue through research, advanced testing methods, education and mitigation technologies. Certainly, there is no one silver bullet approach, and the application of more than one mycotoxin reducing method is required to eliminate mycotoxin contamination effectively. By combining proper silage management, good storage management, physical removal methods, thermal reduction methods and mycotoxin binding by organic feed additives, we can mitigate overall mycotoxin accumulation and risk.