Neurolathyrism risk depends on type of grass pea preparation and on mixing with cereals and antioxidants.

Objective: To study an array of household individual and dietary risk factors for neurolathyrism.

Method: Case-control study using recent cases in a district highly affected by the recent neurolathyrism epidemic in Ethiopia: 108 households with cases and 104 households with no cases; 170 neurolathyrism cases, 370 intra-family controls and 170 community controls frequency matched for age and sex.

Results: A history of acute illness was associated with a two- and threefold increased risk of paralysis in community and intra-family controls, respectively. Soaking grass pea in water before cooking roughly halved the risk of neurolathyrism but cooking in clay utensils more than quadrupled it. Consumption of grass pea in the green unripe and boiled forms increased the risk 10 times or more. Mixing the food with gravy that contains condiments with antioxidant activity reduced it by a factor of 4. The consumption of grass pea mixed with cereals rich in sulphur amino acids was also highly protective, but the magnitude of the effect depended on the grass pea preparation consumed.

Conclusion: Consumption of pure grass pea, especially in the green unripe and boiled forms, should be avoided. Communities at risk of neurolathyrism during famine crises should be encouraged to combine and use grass pea with cereals before the household cereal stock is fully depleted. Breeding programmes, alongside traditional attempts to reduce the toxin content, should enhance the content of sulphur amino acids and antioxidants in grass pea.