Thread by @NaturesPoisons

As promised, more toxic tales as I take a break from #amwriting. What I love about poisons is where it takes you: chemistry, biology, history... maybe the ED or a shallow grave.

Today we'll talk about the neurotoxic, hiccup-inducing, destroyer of kidneys CARAMBOXIN.

Caramboxin is found in starfruit, the fruit that is, uh, shaped like stars. It grows throughout Southeast Asia and tastes like a citrusy apple to me. It's a unique flavor and I rather like it. [pic by Ting W. Chang (CC BY-2.0)]

But you don't want to eat too much of it. I already spoiled it - I'm rightfully accused of being too "telly" in my writing - because of caramboxin.

Caramboxin is a non-proteinogenic amino acid - it's not encoded into our DNA or needed for anything. It's strictly a poison.

In our bodies, glutamate is an excitatory neurotransmitter found extensively in neurons and is responsible for sending signals throughout the body. It's responsible for memory and learning and a ton of other things.

What's this have to do with caramboxin? Well, caramboxin is a glutamate receptor agonist. It mimics the actions of glutamate. You know the saying "too much is never enough"? That doesn't apply here. Too much is bad.

It's like plugging 110-volt hedge clippers into a 220-volt outlet. It'll run like gangbusters for 5 seconds before everything shorts out. Sorry about that, dad.

Caramboxin is like that. It essentially "fries" the nerve endings from overstimulation. We call this excitotoxicity.

But wait, there's more! Caramboxin and its metabolites accumulate in the kidney leading to kidney disease and failure. This is bad. You really need your kidneys.

People with kidney disease or discouraged from consuming starfruit or starfruit juice, but it can affect healthy people, too.

In Brazil, 5 people presented with acute renal failure. Four ate large amounts of starfruit and one drank 10 oz. of pure starfruit juice.

These Brazilians also had vomiting, insomnia, and other signs of neurotoxicity a few hours after consumption, but also hiccups. Yes, hiccups.

Hiccups are a classic sign of kidney disease and renal failure. It sounds funny and is mostly benign, but if you have persistent hiccups for a few days, go to the doctor.

Kindey failure from starfruit is such a common occurrence that the National Kidney Foundation claims you should always avoid starfruit. And if you're a clinician treating someone with kidney failure or disease, you should probably ask about it.

I shop at my local Asian market every week, and every week I see someone with starfruit in their basket, so people are eating it. And I learned from my wife, an awesome RD, that you shouldn't assume people eat like you do. You gotta ask questions!

So that's the tale of CARAMBOXIN, the neurotoxic, kidney wrecking, hiccup inducing poison from our favorite star-shaped fruit. Enjoy!