Poisonous food

Cassava was developed in South America, and introduced to Africa by the Portuguese. What wasn't introduced were the native South American methods of processing it to make it safe. Some were locally developed anyway--but not generally as thorough as the original versions. There were consequences.

An important public health problem arises from heavy dietary reliance on incompletely detoxified cassava among protein-poor populations, particularly in western and southern Africa (Rosling and Tylleskar, 2000). In Nigeria, for example, cassava root (48 mb HCN /100g) is eaten as gari (1.1 mg HCN/100g) and purupuru (4-6 mg HCN/100g) in amounts up to 750 g/day, which corresponds to 8mg and 32-48 mg HCN, respectively (Osuntokun, 1981). The minimal lethal HCN does in humans in 35 mg. "Epidemics of cassava-associated paraparesis (konzo and mantakassa) arising from degeneration of motor nerve cells in the cerebral cortex are reported from cassava-reliant regions of Mozambique, Zaire, and the CAR, among others."

Details about cassav in Burkina Faso. "Cassava contributes greatly to household food security during food shortage period. It sustains families for weeks as food and is also exchanged with other foods or sold to buy food or meet household needs."

Cassava meets a serious need. This is one place eduction can help a lot. "One Congolese researcher who trained with Rosling, Desire Tshala, now at Oregon Health and Science University in Portland, travels for days on dirt roads to teach communities how important it is to soak cassava before consumption.

Nobody knows how the South Americans figured it out, or how the Yandruwandha figured out how to eat nardoo. It may have been a brave man that first ate an oyster, but if you're hungry enough... But who thought of mixing the nardoo with ashes? (Corn needs nixtamalization too, to get full benefit.) It isn't immediately poisonous if you don't, so how do you notice? It isn't as though mixing ashes is an obvious way to spice food--or maybe it is. How does wood ashes compare with, say, pepper? (You first.)