Honey takes on the chemical properties of nectar gathered by bees. This fact turns out to be quite useful if you’re fighting the ancient Romans.
Some plants produce toxins, and some of those toxins get into nectar, and some of that nectar is gathered by bees. The nectar becomes honey with the toxins still in it. Why don’t the toxins bother the bees? Chemical compounds can have different effects on different animals – take cats and catnip, for example. So in some cases bees produce honey that is fine for them but toxic to humans.
Incidentally, when I say “toxins” I don’t mean it in a hand-wavy this-is-a-word-for-any-and-all-pollutants way. I’m talking about neurotoxins, chemicals that get right into the nervous system and push it around. The most notorious of these – at least as it relates to honey – are the grayanotoxins, which come from Rhododendron bushes.
Pliny the Elder (remember his little run-in with a volcano?) wrote about the mænomenon, the “maddening honey” of Turkey. Eat some and you were hit with nausea, delirium, and even paralysis. At one point it was even used as a weapon: the army of Pompey the Great was chasing Mithridates VI and his soldiers across Turkey. Locals, the Heptacomitae, set out large pots of toxic honey for Pompey’s troops. Strabo’s Geography tells us what happened next:
The Heptacomitae cut down three maniples of Pompey’s army when they were passing through the mountainous country; for they mixed bowls of the crazing honey which is yielded by the tree-twigs, and placed them in the roads, and then, when the soldiers drank the mixture and lost their senses, they attacked them and easily disposed of them.
This honey is deliberately produced and sold today in modern Turkey and is valued for its intoxicating properties. Personally, I wouldn’t eat it.
[Thanks to Nicoletta R. for suggesting this topic.]