HUMAN CONSUMPTION OF PLANT MATERIALS WITH NEUROTOXIC POTENTIAL

Humans have a long history of consuming the products of environmentally-tolerant plants with toxic potential; these include Manihot esculenta (cassava), Cycas circinalis (false sago palm) and Lathyrus sativus (grass pea). A number of neurological diseases in humans and animals, are attributed to toxic exposure from these plants. Detoxication of hazardous plant products prior to their ingestion may only remove the acute toxic potential and thereby mask the possibility of long-term adverse effects on health. Establishment of safe levels for human exposure would be facilitated by the development of an animal model of the disease associated with the plant or its toxic principles. Acceptable levels of human exposure would be based on the application of a suitable safety factor to the highest dose which, in controlled experimental studies, fails to elicit disease in the sensitive animal species. This approach is being used to develop acceptable limits of human exposure to the neurotoxic moiety of grass pea, a protein-rich legume widely consumed in the Horn of Africa. Safe strains of grass pea might provide a valuable back-up for protein-poor cassava, both of which exhibit a remarkable tolerance for extreme environmental conditions.