The slopes of the Pontic Mountains above Turkey's Black Sea coast are covered with dense thickets of Rhododendron ponticum and the yellow-flowered Rhododendron luteum. Their nectar contains grayanotoxins, which bees carry into the honey. Turks call the result deli bal, mad honey. Most local beekeepers work on a small scale, so honey from a single hive can carry a heavy dose of toxin.

How grayanotoxins work

Grayanotoxins bind to sodium channels in nerve and muscle cells and prevent them from closing. One result is heightened activity of the vagus nerve, which slows the heart. Mild poisoning brings dizziness, weakness, sweating, salivation, nausea, vomiting and tingling. In more serious cases the pulse slows sharply, blood pressure falls, and heart rhythm and consciousness may be disturbed. Symptoms appear soon after eating, and even small amounts can cause them. In hospital the poisoning is treated with intravenous fluids and atropine, and patients usually recover within a day; deaths in humans are rare. Even so, it remains one of the more common food poisonings in Turkey.

Xenophon and the Ten Thousand

The earliest account comes from the Greek soldier and writer Xenophon. In 401 BC an army of Greek mercenaries known as the Ten Thousand was retreating from Persia to the Black Sea. Near Trapezus, today's Trabzon, the soldiers found a great many beehives and ate the honey. In the Anabasis Xenophon writes that those who ate a little behaved as if drunk, while those who ate a lot seemed mad or even dying. So many lay on the ground that the camp looked as if it had lost a battle. No one died: the next day, at about the same hour, the men came to their senses, and on the third or fourth day they were able to move on.

A trap for Pompey's men

Some three centuries later, in the 60s BC, the Roman legions of Gnaeus Pompeius marched through the same country in pursuit of Mithridates VI of Pontus. The geographer Strabo writes that a mountain tribe, the Heptacomitae, set out mad honey along the Romans' route. Three maniples ate it, lost their wits and were cut down. The story is known only from Strabo, and the sources differ on the exact date.

Mad honey today

Rhododendron honey is still produced in the eastern Black Sea region, and similar honey is gathered by honey hunters in Nepal. Local tradition credits it with healing powers; doctors, however, point out that its toxin content cannot be judged and that a single spoonful can be enough to cause poisoning. Medical reviews also note that honey containing grayanotoxins is increasingly sold online, carrying the risk far beyond the Black Sea. Beyond Turkey and Nepal, doctors have also described mad honey poisoning in North America, Brazil and Japan.

Sources

  1. Gündüz et al. (2008): Clinical review of grayanotoxin/mad honey poisoning past and present
  2. Jansen et al. (2012): Grayanotoxin poisoning – 'mad honey disease' and beyond
  3. Koca & Koca (2007): Poisoning by mad honey – a brief review
  4. Texas A&M Today: Expert gives the buzz on mad honey
  5. Wikipedia: Mad honey (history, Xenophon, Strabo)