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CLAIM: Eating too much cassava can be deadly.
VERDICT: MISLEADING. Credible medical publications and professionals reveal that an individual is at death risk if he or she consumes cassava produce that has been prepared haphazardly.
Full Text
Cassava is a highly consumed food in Nigeria. Globally, the country is recognised as the highest exporter of produce and accounts for one-third of cassava production in Africa.
However, a Facebook handle, identified as THE APOSTOLIC CHURCH (YOUTH WINGS), has stated in a post that excessively consuming cassava can be life-threatening.
“Eating too much cassava can be deadly,” part of the post reads.
The post cites that the root crop contains cyanogenic glycosides, which can release cyanide gas. It also cautioned that any food product from the crop should be properly prepared before consumption.
Knowing how well cassava is cherished, especially as a staple food among Nigerians, we decided to fact-check the assertion.
Verification
Writing for MedicalNewsToday, Danielle Dresden highlights the nutritional value of cassava and identifies it as a source of energy, protein, calcium, and fibre.
Nutritional content
She writes that the crop is a good source of vitamin C, thiamine, riboflavin, and niacin. Furthermore, according to the article, cassava is a good source of resistant starch, which health experts say can improve gut health.
This is also a fact that Healthline shares, as Rachael Ajmera and Brianna Elliot further mention some of its nutritional content. They include calories, protein (1.5 gram), fat (3g), carbs (40g), fibre (2g), vitamin C (20% of daily value), copper (12% of DV), Thiamine (7% of DV), folate (6% of DV), vitamin B2 (6% of DV), potassium (6% of DV), magnesium (5% of DV), and niacin (5% of DV).
But does cassava have any poisonous or harmful food material?
MedicalNewsToday informs about the toxic properties that may materialise as a result of consuming the food product and acknowledges it as a consequence of improper preparation.
Ms Dresden explains that an individual risks health-related injuries if he consumes cassava in its raw form. She links the cause to the presence of “naturally occurring forms of cyanide” within the crop and asserts that it triggers poisoning if ingested.
Significantly, she attributes some major occurring health deficiencies, including body paralysis, low levels of iodine, abnormal growth such as goitre, poor vision and even death, in areas where cassava is constantly consumed.
However, the toxicity in cassava is not hinged only on the cyanide it contains. It can also endanger the health of human beings when air pollutants settle on its upper part, such as its stalk and leaves. According to Ms Dresden, pollutants such as trace metal elements, herbicides and pesticides circulate in the environment and sometimes settle on the plants.
Both Ms Ajmera and Ms Elliot caution in their article for Healthline that cassava should be consumed in “moderation” due to its high calories and harmful chemicals.
They also advise that before the plant is eaten, it must be properly cooked because it is poisonous if consumed raw. They explain that cassava, in its raw form, contains a chemical material identified as cyanogenic glycosides.
They both assert that constantly consuming cyanogenic glycosides can trigger cyanide poisoning, a situation that is very well associated with impaired thyroid and nerve function, paralysis, organ damage, and death.
Although both research authors state categorically that processing methods of the crop, such as peeling, chopping and cooking, can reduce its nutritional value, they still advise the culture of cooking the root crop before consumption. They added that cooking methods such as boiling retains more of the crop’s nutrients compared to roasting and frying.
A 2017 CDC situation report in Uganda
Back in 2017, the Centre for Disease Control and Prevention (CDC) encountered an epidemic situation in Kasese district in western Uganda. However, the epidemic was only unravelled after a certain funeral had been conducted on Sept. 5, 2017, and about 15 persons were diagnosed with similar ailing conditions.
The affected persons shared identical symptomatic conditions such as diarrhoea, vomiting, and abdominal pains, which later were linked to food poisoning. An investigation was consequently carried out, and it was discovered that the victims of the poisoning had consumed a cassava dish of cassava flour mixed with hot water.
Upon further findings, it was discovered that all the victims had bought cassava flour from retailers who had, in turn, purchased the flour from a single wholesaler, whose product was found to have a “high cyanogenic content.”
When the compromised bags of cassava flour were seized, and laboratory analyses were carried out, it was discovered that the cyanide content was equivalent to an average of 88 parts per million (ppm) of cyanide. That is eight times more than the recommended “safe level” of 10 ppm needed.
Thereafter, health education and orientation were given to the locals of the Kasese about cyanide poisoning and the processes to adopt to reduce its content in cassava.
Why is cyanide inherent in cassava?
A National Library of Medicine (NLM) study reveals that cassava leaves and roots cannot be consumed due to two cyanogenic glycosides- linamarin and lotaustralin.
Both are decomposed by linamarase, a naturally occurring enzyme in cassava used to liberate hydrogen cyanide (HCN) from the crop. The study further reveals that 5/6 of cyanogenic glycosides are broken down by linamarase, thus allowing HCN to escape into the air and making cassava edible for consumption.
However, that process doesn’t completely erase the cyanogenic material from the crop, but the rest is cleared out during digestion through detoxification.
Centre for Food Safety writes that cyanide glycosides are a group of chemical compounds which occur naturally in over 2000 plant species. It further asserts that about 25 cyanide glycosides are found in edible plants.
Significantly, the study mentions that cyanogenic glycosides are “non-toxic,” but due to the presence of enzymatic hydrolysis by beta-glucosidase, following maceration by plant tissues, cyanogenic glycosides are broken down to release hydrogen cyanide. This hydrogen cyanide can be very toxic to both plants and animals.
What experts say
In a conversation with food nutritionist and dietician Temiloluwa Omotoso, she divulged that cassava in its raw form is very poisonous. She further stated that because cassava is a root crop, it contains a material she identified as cyanogenic content. Consequently, the crop has to be properly processed to get rid of the material.
Ms. Omotoso highlighted a host of processing methods that could be adopted to eliminate cyanogenic content in cassava. She explained that locally, especially in the production of Garri and fufu, cassava is usually soaked, cooked, or fried.
She emphasised that heat kills off cyanide in food crops and guarantees healthy consumption when people consciously adopt the culture of properly cooking the food crop.
She also made mention of soaking the cassava tubers in water for a longer duration of time, as this method weakens and neutralises the cyanide toxicity.
However, the dietician informs that aside from an intentional practice of correctly processing cassava, nothing else makes it a death risk for consumption, not even excessive consumption. She says there is no scientific backing for that.
Also, in a correspondence with another dietician, Bunmi Ojo, who works at the University College Hospital (UCH) Ibadan, she identified that all foods contain nutrients.
She further agreed that cassava contains toxicants, which she identified as cyanide. However, she noted that if rightly prepared– washing, peeling, fermenting, etc– the toxic material reduces to the bare minimum.
The dietician pointed out that cases where bizarre casualties- including death- occur after food intake can be attributed to poor preparation of such foods.
Ms Ojo also noted that death may not be the immediate repercussion but that damages can occur internally, destroying body organs and even leading to body paralysis.
She advocated for careful processing and preparation of cassava produce: peeling, soaking and frying it before consumption.
Conclusion
The claim is misleading. Credible medical publications and observations by experts all emphasise that a person is only at risk of incurring death if the cassava food consumed is not properly prepared.
