Methylene cyclopropyl acetic acid (MCPA) is found in lychee seeds and also a toxic metabolite in mammalian digestion after eating hypoglycin, present in the unripe ackee fruit, grown in Jamaica and in Africa.

Methylene cyclopropyl acetic acid (MCPA) is a compound found in lychee (Litchi chinensis) seeds.

[3] MCPA forms non-metabolizable esters with coenzyme A (CoA) and carnitine, causing a decrease in their bioavailability and concentration in bodily tissue.

Depending on the severity of the case, the symptoms range from headache, rapid heart beat and sweating to dehydration and low blood pressure stemming from intense vomiting, to delirium and coma, and finally seizures and death.

The vast majority of the fatalities were undernourished children, their preexisting low blood sugar detrimentally amplifying the effects.