Lessons from the Litchi


The litchi (or lychee) fruit ripens in the heat of the summer in India, before the monsoons. In May and June the tree limbs begin to blossom with small greenish gray flowers that will eventually become bunches of the sweet, soft, fruit encased in a nut-like suit of armor. In the United States, Litchi martinis make a great hit at a party (http://www.foodnetwork.com/recipes/lychee-martini-recipe.html), the sweetness of the succulent fruit provides a burst of flavor in a dry martini, for even the most discerning palate. Litchis have long been a delicacy in the warmer climes of Southern China and India. The benefits of the litchi stem primarily from the large amount of the antioxidant Vitamin C that it provides. It is also a fun fruit to eat, with its hard outer shell that must be broken open to the sticky softness of inner portion, when ripe, melts in your mouth.

But appearances can be deceiving – a recent article in the Lancet revealed that the litchi indeed has a sinister side (http://dx.doi.org/10.1016/S2214-109X(17)30046-3).  The fruit, while high in Vitamin C, also has large quantities of molecules called hypoglycin A and hypoglycin B. The two compounds when ingested in high quantities, stop the regular breakdown of fatty acids in the liver – and result in bubbles of fatty acids in that organ. If the body cannot break down these fatty acids (which it does naturally to make more glucose) it needs to rely solely on glucose and glycogen for energy. Once those stores are depleted, more are not generated because hypoglycin also affects the build up of glucose. The person ends up with very low sugar levels, and “hypoglycemic”.  Intense hypoglycemia can cause vomiting, seizures, and comas, and even death.

Jamaican vomiting sickness (JVS), also called toxic hypoglycaemic encephalopathy, is caused by ingestion of too much of a fruit  very similar to the litchi called “ackee”. Doctors often give activated charcoal to the patients, because of its known ability to adsorb toxins from the body. It turns out the litchi has similar properties to the ackee fruit when eaten on an empty stomach.

For a long time, people thought that Jamaican Vomiting Sickness, and the encephalitis caused by litchis, was actually due to some sort of pesticide poisoning. But it turns out – it is the litchi itself, or in the case of JVS, unripe ackee fruit. Both contain high levels of the toxins and when people (specifically small children) do not eat their dinner, but rather lots and lots of partially ripe litchis from the ground, they end up with untenable amounts of dangerous compounds in their system.

The authors, Aakash Shrivastava et al., took patients that were admitted to two hospitals in one of the largest litchi cultivation regions in India, Muzaffarpur. They specifically isolated patients who met their “case definition” meaning children age 15 or younger, with sudden onset siezures and/or altered mental states. The researchers performed a battery of tests including those for hypoglycin A in the blood, as well as the compound that is generated from hypoglycin- methylenecyclopropylglycine (MCPG) It turns out, that most of the patients had something in common – they had eaten large portions of litchis, and had not eaten dinner that day. The two in combination resulted in the severe, and possibly deadly, illness.

But really, why should we care about this? Well, tiny rural settings in countries like India, Southeast Asia, Africa – you name it, the poorer places, often have unexplained illnesses whose etiology is never pursued. Children die, parents mourn, and life goes on until the next outbreak. There is a very real need for public health service in these regions, to help families from losing their children from something as simple as eating too much fruit lying on the ground… So achingly sweet, so soft and chewy. And so dangerous.

The beauty and fine taste of the litchi are well described in the poem below written by a 19 year old poet named Nakune.

3. Peter S. Spencer and Valerie S. Palmer.  The enigma of litchi toxicity: an emerging health concern in southern Asia. 30 Jan 2017. The Lancet Global Health Vol. 5 No. 3. DOI: http://dx.doi.org/10.1016/S2214-109X(17)30046-3