Cassava cyanogens and fish mercury are high but safely consumed in the diet of native Amazonians.

The two most important staple foods (cassava and fish) in the diet of native Amazonians contain neurotoxins (linamarin and monomethyl mercury, MMHg). These same neurotoxins are public health issues in other parts of the world. Factors such as chemistry, environment, and human ecology determine the endemism of neuropathies caused by consumption of cassava (Manihot esculenta Crantz) and fish. Linamarin is a natural component of cassava tubers that can be destroyed before consumption by proper processing. Furthermore, small amounts of the toxin absorbed by people consuming cassava can be effectively metabolized if the diet contains adequate protein-containing sulfur amino acids. Naturally occurring Hg in the waters of the Amazonian rain forest is methylated to MMHg by microorganisms and bioconcentrated in the aquatic food chain. There is no effective method for MMHg removal from fish. Despite high concentrations of naturally occurring neurotoxins in cassava (linamarin) and fish (MMHg), daily consumption of these foods in large amounts over the course of a lifetime poses no health hazards for Amazonians.