CASSAVA’S CYANIDE-PRODUCING ABILITIES CAN CAUSE
A cassava plant usually reaches 3 to 4 feet in height, though
some plants can grow up to 13 feet tall.
COLUMBUS, Ohio – Cassava is the third-most important food source in
tropical countries, but it has one major problem: The roots and leaves
of poorly processed cassava plants contain a substance that, when eaten,
can trigger the production of cyanide.
That’s a serious problem for the 500 million people who rely on
cassava as their main source of calories, among them subsistence farmers
in Sub-Saharan Africa, said
Richard Sayre, a professor of
biology at Ohio State University. He and his colleague Dimuth
Siritunga, a postdoctoral researcher in plant biology at the university,
have created cyanogen-free cassava plants. A cyanogen is a substance
that induces cyanide production.
Their study appeared in a recent issue of the journal
Cassava is a hardy plant – it can remain in the ground for up to two
years and needs relatively little water to survive. It’s the key source
of carbohydrates for subsistence farmers in Africa. But an unprocessed
cassava plant contains potentially toxic levels of a cyanogen called
The proper processing of cassava – drying, soaking in water, rinsing
or baking – effectively reduces cassava’s linamarin content. But, said
Sayre, shortcut processing techniques, which are frequently used during
famines, can yield toxic food products.
“If we could eliminate the cyanogens in cassava, the plant wouldn’t
need to be processed before it’s eaten,” he said. “In Africa, improperly
processed cassava is a major problem. It’s associated with a number of
cyanide-related health disorders, particularly among people who are
Cyanogens in cassava plants convert to cyanide when raw
cassava is eaten or processed.
Chronic, low-level cyanide exposure is associated with the
development of goiter and with tropical ataxic neuropathy, a
nerve-damaging disorder that renders a person unsteady and
uncoordinated. Severe cyanide poisoning, particularly during famines, is
associated with outbreaks of a debilitating, irreversible paralytic
disorder called Konzo and, in some cases, death. The incidence of Konzo
and tropical ataxic neuropathy can be as high as 3 percent in some
People who get little or no protein in their diets are particularly
susceptible to cyanide poisoning, as they lack the proper amino acids
necessary to help detoxify the poison.