I’ll preface this with “I still ate it,” but star fruit contains a deadly neurotoxin called caramboxin. 😱*clutches pearls*
Luckily, if you have normally functioning kidneys, caramboxin gets flushed out of your system and does absolutely no harm. In fact, my friend from Taiwan says they eat star fruit daily, and they’re all doing fine so, again, totally fine for most people to eat. However, if you have kidney disease, the toxin does not get removed and it can go on to interfere with your neurons.
Neurons pass messages around your body. Molecules called neurotransmitters are released from one neuron and passed to another in order to relay that message. The neurotransmitters fit snuggly into proteins called receptors on the next nerve. This is kind of like a lock and key. Once the receptor is “unlocked” by the neurotransmitter “key,” the nerve passes the message to another nerve, and so on. Caramboxin can “unlock” and stimulate some of these nerves by snuggling up to the receptor. Normally, turning on neurons is a very controlled process, so when caramboxin gets in there, it messes things up. Symptoms include mental confusion, vomiting, and seizures, and in some cases, coma and death.
Interestingly, an early symptom of caramboxin poisoning is intractable hiccups, so if that happens to you after eating star fruit, call the doctor and ask about some kidney labs!
This was my first star fruit ever! I don’t think I let it ripen enough, but it tasted like a wet tart apple. Should I wait longer next time based on that green color? No hiccups yet!😉
Source: Garcia-Cairasco et al 2013 https://doi.org/10.1002/anie.201305382