US and Indian scientists say a mystery illness that killed more than 100 children a year in northern India was caused by eating lychees on an empty stomach.
For more than two decades, apparently healthy children in a region of Bihar suffered sudden seizures and lost consciousness.
Almost half died, baffling doctors.
New research, published in the medical journal The Lancet , now suggests they were poisoned by the fruit.
Most of the victims were poor children in India's main lychee-producing region who ate fruit that had fallen on to the ground in orchards, the journal said.
Lychees contain toxins that inhibit the body's ability to produce glucose, which affected young children whose blood sugar levels were already low because they were not eating dinner.
They woke screaming in the night before suffering convulsions and losing consciousness as they suffered acute swelling of the brain.
Researchers examining sick children admitted to hospital in Muzaffarpur between May and July 2014 found a link to an outbreak of sickness that caused brain swelling and convulsions in children in the Caribbean.
That outbreak was caused by the ackee fruit, which contained hypoglycin, a toxin that prevents the body from making glucose. Tests then showed that lychees also contained hypoglycin.
This led health officials to tell parents to make sure young children got an evening meal and limit the number of lychees they were eating.
Children suffering symptoms associated with the outbreak should be rapidly treated for hypoglycaemia, or low blood sugar, officials said.
The number of reported cases of the sickness has since fallen from hundreds each year to about 50, the New York Times reported.