Mad about that cup of tea? Honey pours from the bottle in slow motion—the thick syrup forming a column of sweet goodness that dissolves with a few stirs, infusing its luscious flavor. It seems remarkably simple, yet making honey is a feat of nature. Honeybees must first forage for nectar-producing flowers. The worker bees then suck the liquid nectar with their proboscis and store it in a tiny honey stomach until they revisit the hive. Once the worker bee returns home, the nectar is processed by house bees, which enzymatically digest the liquid. Eventually, the honey gets deposited into the hexagonal honeycomb cells. The bees continue to ripen the honey before finally sealing the cell with wax. It’s the nectar collected from flowers that imparts different flavors to the honey. In some cases, it’s delicious—BUT in others, it’s poisonous.
Most people are familiar with clover honey and honey made from the nectar of berry bushes (blackberry, raspberry, and strawberry) or fruit trees (apples, peaches, and cherries). But honey made from the flowers of rhododendrons, Japanese pieris, and mountain laurel can be toxic. These plants contain the neurotoxins grayanotoxin and andromedotoxin, not only in their nectar but also in their leaves (tea brewed from their leathery leaves is another way of poisoning.)
Honey made from these plants is sometimes called mad honey. Varying amounts of grayanotoxins in the honey produce symptoms ranging from impaired consciousness, dizziness, faintness, or hallucinations (hence mad honey) to sudden vomiting, decreased blood pressure, and chest pain similar to that found with a heart attack. Large doses of grayanotoxin-contaminated honey can produce seizures and cardiac dysrhythmias that may result in death if untreated.
Honey from Turkey (deli bal or tutan bal) has been implicated in mass poisoning. The common rhododendron (Rhododendron ponticum and subspecies) found in the eastern part of Turkey is responsible. Yet local beekeepers can determine when toxins are present as the honey is bitter, producing a burning sensation in the throat.
An Athenian military commander, Xenophon, described an incident of mad honey poisoning, noting that his army was incapacitated for days after eating honey from hives in the Black Sea region of Turkey. His men suffered gastrointestinal disturbance and an inability to stand steady. Knowledge of this was not lost on King Mithridates (from the Kingdom of Pontus surrounding the Black Sea), whose allies used the honey to poison Pompey’s army in 69 BCE to gain a tactical advantage.
Honeybees are important pollinators, and their day-to-day efforts are a huge benefit for agriculture. They also create a unique sweet syrup prized since the early days of civilization. And as long as the honey comes from plants other than those with grayanotoxins, we can all be just mad about honey.