Plants That Kill: Ackee

Adapted from pages 158-159 of Plants That Kill:

Although it has also been introduced to the other Caribbean islands, Central America and Florida, ackee is widely eaten only on Jamaica. In fact, it is Jamaica’s national fruit, and ackee and saltfish is the national dish. The leathery fruit are 7.5–10 cm (3–4 in) long, bright red or yellow-orange when ripe, and split open into three sections to expose three shiny black seeds, each surrounded by a large yellow or whitish aril. Only arils from ripe fruit that have naturally split open are eaten. To remove any residual toxicity, they are cleaned of all red fibre (the aril membrane) and boiled, and the water they are boiled in is discarded. Cooking unripe arils does not destroy their toxicity.

The ackee tree (Blighia sapida) has pairs of glossy leaves. Its fruit ripen to red and, when they split open, the cream arils within can be eaten after cooking.
Photo credit: Shutterstock, twiggyjamaica

Before the toxicity of ackee was understood, eating unripe arils frequently caused poisoning known as Jamaican vomiting sickness, which occurred as an annual epidemic. Symptoms included vomiting, convulsions and, frequently, also coma and death, with mortalities being more common in children, particularly those already suffering from malnutrition. The underlying cause was eventually linked to the consumption of unripe ackee arils. This results in low blood sugar levels (hypoglycaemia) through a blockade of the liver’s ability to synthesize glucose and a reduction in fatty acid metabolism (both normal routes for increasing levels of blood sugar), as well as depletion of the liver’s carbohydrate reserves. 

Poisoning is due to the presence of an amino acid derivative, hypoglycin A (2-amino-3-(methylenecyclopropyl)- propionic acid), which is also found in other plants of the soapberry family, such as lychee (Litchi chinensis). In ackee, the concentration of hypoglycin A is high in unripe arils and reduces significantly as they ripen, although low levels remain in the aril membrane. The seeds also contain the less toxic hypoglycin B (the gamma-glutamyl conjugate of hypoglycin A), with concentrations significantly increasing as the seeds ripen. 

Plants That Kill: A Natural History of the World’s Most Poisonous Plants
By Elizabeth A. Dauncey & Sonny Larsson

This richly illustrated book provides an in-depth natural history of the most poisonous plants on earth, covering everything from the lethal effects of hemlock and deadly nightshade to the uses of such plants in medicine, ritual, and chemical warfare.

Featuring hundreds of color photos and diagrams throughout, Plants That Kill explains how certain plants evolved toxicity to deter herbivores and other threats and sheds light on their physiology and the biochemistry involved in the production of their toxins. It discusses the interactions of poisonous plants with other organisms–particularly humans—and explores the various ways plant toxins can target the normal functioning of bodily systems in mammals, from the effects of wolfsbane on the heart to toxins that cause a skin reaction when combined with the sun’s rays. This intriguing book also looks at plants that can harm you only if your exposure to them is prolonged, the ethnobotany of poisons throughout human history, and much more.

A must for experts and armchair botanists alike, Plants That Kill is the essential illustrated compendium to these deadly and intriguing plants.

  • Provides an authoritative natural history of the most poisonous plants on earth
  • Features hundreds of color illustrations throughout
  • Looks at how and why plants produce toxins
  • Describes the effects of numerous poisonous plants, from hemlock and deadly nightshade to poppies and tobacco
  • Explains poisonous plants’ evolution, survival strategies, physiology, and biochemistry
  • Discusses the uses of poisonous plants in medicine, rituals, warfare, and more


This post is part of a series, explore additional posts here<< Plants That Kill: CapsaicinPlants That Kill: Cycads >>