Understanding Natural Toxins in Food
A toxin is a harmful substance produced within living cells or organisms.
We will be taking a look at some toxins that exist naturally in living organisms that we consider as food.
It is important to note that these toxins do not cause harm to the organisms themselves but may constitute harm when eaten by other creatures including animals and man.
Therefore, extra processing steps are required before consumption as food in order to reduce the level of toxicity to what the body can detoxify seamlessly.
So, why does an organism have to produce toxins?
- To act as a defense mechanism against predators such as man, animals, insects and even microorganisms.
- As a response to stress such as cuts or bruises.
- As part of its life cycle activities.
Below are some common food toxins:
- CYANOGENIC GLYCOSIDES
Occurring naturally in over 1800 plant species is cyanogenic glycosides. Some of these plants are used as food. Examples: cassava, almond, sorghum, etc. Signs of acute cyanide intoxication include: dizziness, diarrhoea, vomiting, drop in blood pressure, rapid breathing, cyanosis, terminal coma, etc. Cyanide intoxication can lead to death when the cyanide level exceeds the lethal dose or the limit the individual is able to detoxify.
Peeling, soaking in water, boiling, fermenting, frying, etc are all processes that reduce cyanide levels.
- LECTINS
Lectins are found in beans with the highest concentration found in red kidney beans. Signs of acute lectin intoxication include: severe stomach ache, vomiting and diarrhoea, etc. Lectins are destroyed by soaking dried kidney beans in water for at least 12 hours and then boiling for at least 10 minutes in water.
Note that canned kidney beans have already undergone this treatment during factory processing.
- MUSCIMOL AND MUSCARINE
Muscimol and muscarine are toxins commonly found in wild mushrooms, exhibiting toxic effects on the liver, kidney and nervous systems. Intoxication signs include: vomiting, diarrhoea, confusion, hallucinations, etc. These toxins are not inactivated by peeling or cooking. Thus, avoidance of wild mushrooms are recommended unless identified as non-poisonous.
- MYCOTOXINS
Produced by certain types of moulds are mycotoxins. Moulds infest various foods in the farm, in storage and even after processing leaving behind these mycotoxins. Food-borne mycotoxin intoxication can cause severe illness, immune deficiency and even death shortly after consumption of highly contaminated foods.
- AQUATIC BIOTOXIN (Algal toxins and Ciguatoxins)
Algal toxins are produced by some algae species in oceans/ fresh water during periods of bloom. These algae are eaten by fish and shellfish (such as mussels, scallops and oysters) and the toxins are retained in them till they are eaten as food by man or animals. Signs of algal intoxication include: diarrhea, vomiting, tingling, paralysis, etc.
Ciguatoxins are produced by dinoflagellates which serve as food for fish. These toxins are retained in the fish leading to Ciguatera Fish Poisoning (CFP) when eaten by man and animals. Examples of fish that retain ciguatoxins include: barracuda, dog snapper, king mackerel, etc. Signs of CFP include: nausea, vomiting, and neurologic symptoms, such as tingling sensation on fingers and toes.
About the Author
Chidinma Ezinne Ochulor is a certified Food Technologist, a quality assurance professional with over 3 years' experience. She is a professional member of the Nigerian Institute of Food Science and Technology (NIFST). Reach her on LinkedIn, here.
