MYCOTOXINS: DANGERS OF FREQUENT CONSUMPTION OF NSIMA AND RICE AMONG MALAWIANS

A toxin is a poisonous substance produced by the biological processes of biological organisms. Mycotoxins are naturally occurring toxins that are produced by moulds or fungus and can be found in food. The moulds grow under warm and humid conditions on crops and foodstaffs like cereals, nuts, spices, dried fruits, apples and coffee beans (WHO, 2023)

There are over 500 mycotoxins that have been identified, but the most commonly ones that affect livestock and human health are; Aflatoxins, Ochratoxins, Fumonisins, Trichothecenes and Zearalenones. In this article, much examples will dwell on aflatoxins as a special type of mycotoxins which is found in staple foods commonly in Malawi while some examples will include general features of mycotoxins.

Figure showing various types of mycotoxins

Aflatoxins are amongst the most poisonous mycotoxins. They are produced by Aspergillus flavus and Aspergillus Parasiticus which grow in soil, decaying vegetation, hay and grains. The most favourable conditions for growth of Aspergillus fungus is humid environment with warm temperatures which fosters multiplication of molds thereby producing more amounts of aflatoxins.

International Agency for research on cancer outlines that aflatoxins are proven human carcinogens. That is to say, frequent consumption of foods containing aflatoxins can cause cancer. Statistics from Partnership for aflatoxin control in Africa (PACA) found out that 95% of groundnuts samples in 19 districts of Malawi were detected containing aflatoxins. This study on groundnuts which is a type of grain could show a glimpse of how grains in Malawi put risk on the people of developing health complications when frequently consumed.

It should be noted that mycotoxins are found naturally in some foods like grains and cereals. Grains e.g maize and cereals like rice, for example contain variant mycotoxins like Aflatoxins B1 and B2, Ochratoxins A and B, Penicillin acid, Citrinin, among others. The reason why we do not die after eating cereals is that the mycotoxin level present is usually in small amount making the cereals and grains edible. Our bodies also have natural detoxification processes happening in the liver which break down and eliminate mycotoxins. Apart from this, some compounds in the food e.g antioxidants usually counteract the operations of mycotoxin thereby reducing their toxicity level. Mycotoxin level can also be reduced by boiling and processing the cereals. Boiling only reduces the number of mycotoxins, it does not extinct the mycotoxins in the food. Inorder to ensure safety, countries set food standards that outline maximum allowable limit of mycotoxins in food products.

However, regular consumption of low levels of mycotoxins over a long period of time increase the risk of suffering from harmful health effects like immune deficiency as well as cancer. Most Malawians rely on maize flour consumed as Nsima for staple food with some alternative of rice. Both of these contains some aflatoxins which when consumed over time can bring harmful health effects on people. Ensuring balanced diet, not only relying on grains and cereals but also consuming vegetables, fruits, dairy products and protein foods consistently over time, can reduce implications which come as a result of mycotoxins. Some individuals, especially the elderly, young children and those with compromised immune systems may be more susceptible to mycotoxin toxicity.

As noted above, the effects of mycotoxins are harmful to people’s health and level of mycotoxins in grains and cereals need to be reduced to reduce the risks associated with mycotoxins. Inorder to achieve this, Professor Limbikani Matumba of Lilongwe University of Agriculture and Natural Resources (LUANAR) together with other 6 scholars in their research proposed five preventive and control measures for mycotoxins in grains:

1.Sustaining plant’s vigour and health

2.Reducing mycotoxigenical fungal population in growing plants and storage

3.Reducing moisture content of grains and avoiding rehydration

4.Safeguarding husks/hulls or pericarp/testa 

5.Cleaning and removing mycotoxin high risk components.

Health plants are less susceptible to fungal attack and therefore less chance of increase in levels of mycotoxins. The mycotoxigenical fungus can be reduced by growing only unaffected seeds after selecting affected seeds and safely disposing them. Also use of fungicides can help in combating the fungus in growing crops. Harvested grains and cereals need to be dried to remove all the moisture and store in a cool, dry place to prevent rehydration which can put the grains at risk of fungal infection which could increase the level of mycotoxins. Lastly, all tools and storage facilities should be cleaned regularly to prevent habiting of fungus which put risk of increase in level of mycotoxins.

References

Limbikani Matumba, S. J.-M. (2021). Five keys to prevention and control of mycotoxins in grains: A proposal. Global Food Security, 30(2).

PACA. (2019). Strengthening Aflatoxin control in Malawi: Policy recommendations. Based on findings of the country-led situation analysis and action planning (C-SAAP) conducted from 2014 to 2018 by the Partnership for Aflatoxin Control in Africa (PACA). 

World Health Organisation. (2 October 2023). Mycotoxins. WHO.

 IARC. 2002. Aflatoxins. In Traditional Herbal Medicines, Some Mycotoxins, Naphthalene and Styrene. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 82. Lyon, France: International Agency for Research on Cancer. pp. 171-366