Tutin is a naturally occurring neurotoxin that can pose a risk to human health through the consumption of contaminated honey. This compound originates from specific plant sources and enters honey via a specific pathway. While primarily a concern in regions like New Zealand, understanding its origins and effects is important for consumers globally.
The Source of Tutin
Tutin is derived from the tutu plant, Coriaria arborea, a shrub native to New Zealand. The plant contains tutin, a neurotoxin. The plant itself does not directly transfer the toxin to bees through nectar or pollen.
The contamination pathway involves a specific insect, the passion vine hopper (Scolypopa australis). This insect feeds on the sap of the tutu plant, ingesting the tutin. The passion vine hopper then excretes a sugary substance known as honeydew, which contains the ingested tutin.
Honey bees collect this toxic honeydew, especially when other floral nectar sources are scarce, such as during hot, dry weather. The bees then bring the contaminated honeydew back to their hives, incorporating it into the honey they produce. Tutin, harmless to bees, becomes concentrated in honey, posing a risk to humans.
Health Effects of Tutin
As a neurotoxin, tutin affects the nervous system. The severity of symptoms from tutin poisoning can vary widely depending on the amount of contaminated honey consumed and an individual’s sensitivity. Symptoms appear within hours of ingestion.
Mild symptoms include giddiness, exhaustion, nausea, vomiting, dizziness, and headaches. Higher doses lead to more severe neurological effects, which can escalate to tremors, seizures, stupor, and even coma.
In extreme cases, tutin poisoning can lead to respiratory failure and death. A notable outbreak occurred in 2008 in Whangamata, New Zealand, where 22 people were poisoned by contaminated comb honey.
Ensuring Safety from Tutin
Consumers can take several steps to ensure their safety from tutin-contaminated honey. Purchasing honey from reputable commercial sources is a primary safeguard. Regulatory bodies, such as the Ministry for Primary Industries (MPI) in New Zealand, implement strict standards for tutin levels in honey sold for consumption.
These regulations set maximum allowable limits for tutin in honey. For extracted honey, the limit is 0.7 mg/kg, while for cut comb honey, a stricter limit of 0.01 mg/kg applies due to potential uneven distribution of the toxin. All honey intended for sale or export must comply with these limits.
Beekeepers play a significant role in minimizing tutin contamination risks. They are advised to place hives away from tutu plants, particularly in known high-risk areas. Harvesting honey before the peak risk period, which typically occurs from January to April, also helps reduce the likelihood of contamination.
Regular testing of honey samples at certified laboratories is a common practice for commercial beekeepers to verify compliance with safety standards. Consumers should exercise caution with homemade or untraceable honey, especially if it originates from regions where tutu plants are prevalent.