Which brings us back to the patient with liver disease. For people with a different version of the enzyme which deactivates coumarin, both warfarin and coumarin are thought to be particularly toxic. There’s no way of knowing which camp you fall in, short of a trip to the emergency room or a genetic test.
“It has an effect on the liver and all kinds of other compounds have an effect on the liver, like alcohol especially. And so you never know if you get liver disease from coumarin or something else,” says Lachenmeier.
Globally, there were around a million deaths from liver disease in 2010 – that’s around 2% of all deaths. We may never know if coumarin was involved, but a recent report concluded that for those with the highest intakes, health risks cannot be ruled out.
Armed with the knowledge that tonka may or may not kill me, it’s time to put my baking skills to the test. Raquel recommends grating some tonka bean into macaron batter, then coating the finished shells in chocolate ganache and serving them with a sour cherry in the middle. Alas, my cooking skills are usually limited to microwave mug desserts, so I opt to bake some into cupcakes instead.
Half an hour later, I’m standing over a batch of slightly sad-looking cakes, which smell faintly of almonds. It’s only polite to share your toxic snacks with your friends, so I test one on my flatmate. She takes a bite and chews thoughtfully. “It tastes like feet.”
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