Why a little bit of poison is (sometimes) good for us

• Most Delicious Poison is filled with illuminating insights into the natural world 
• READ MORE:  If you're lost in the woods, ask a tree for directions! Author writes about the 'extraordinary powers' of plants

NATURE

Most Delicious Poison

by Noah Whiteman (Oneworld £20, 304pp)

A few years ago, a friend of mine dug up some parsnips from her allotment and took them home to roast with the Sunday lunch. 

Shortly afterwards, she and her husband were in A&E — it turned out that one of the ‘parsnips’, an unusually misshapen one, was actually a highly toxic mandrake root. Although they were violently ill for several days, they survived.

Mandrake is one of the natural poisons that U.S. evolutionary biologist Noah Whiteman profiles in this book, whose title comes from Shakespeare’s Antony And Cleopatra.

The Egyptian queen so pines for absent Antony that she asks her lady-in-waiting for a mandrake tonic, ‘most delicious poison’, to send her into a prolonged sleep so she can forget about her lover. Of course, it might kill her off altogether.

Whiteman is fascinated by what he calls the ‘paradox of toxins’: that things that could kill you off in large doses are often, in small doses, highly beneficial.

Mandrake is a good example of this. It contains scopolamine, which can be fatal, but which, in small quantities, is used in a patch that can combat travel sickness.

Plants have evolved to produce different chemicals which either repel animals, or draw them in, but over centuries, humans have turned the tables by tapping into these chemicals for purposes like medicine. 

From aspirin (made from willow bark) to pyrethrin (made from chrysanthemums, and used in flea treatments for pets), these naturally-occurring toxins are part of our everyday lives.

Many of these, Whiteman points out, were known to indigenous healers long before scientists cottoned on to their usefulness. One of the best examples of this is yew. 

For thousands of years the yew’s toxins, which have evolved to dissuade animals from eating the evergreen, have been used to poison arrow tips or as a lethal potion to be fed to an enemy. 

Yet in the past 50 years, the lives of countless cancer patients have been extended by a compound from these same toxins — most famously by the breast-cancer drug Taxol.

In nature, caffeine has just one function: to drive away bugs and herbivores that would otherwise feast on the leaves of caffeine-producing plants, such as coffee, tea and some citrus trees. Yet, thanks to human ingenuity, we have harnessed this powerful natural insecticide for our own pleasure.

In extreme cases, though, caffeine can be fatal even to humans. In 2001, a young man in Australia died from an accidental caffeine overdose, having added pure caffeine powder to a protein shake — the equivalent of drinking 50 cups of coffee.

Like caffeine, the kick that we get from spices is something that evolved to benefit the plant. In the tiny doses that we consume, the seeds of spices such as cardamom, cumin, fennel, peppercorns, nutmeg and turmeric are both harmless and delicious, but for smaller animals, they are unpalatable and can be poisonous to some.

Most Delicious Poison is full of illuminating insights into the natural world and the plants that have shaped us — but be warned, it contains a lot of chemistry, so it helps to know your alkaloids from your terpenoids.

Whiteman traces his interest in toxins back to the death of his father from complications due to a long-term addiction to those familiar poisons, drugs and alcohol, and his grief for his father’s chaotic life and death runs like a thread through this book.

‘My attempt to grasp why he died allowed me to identify and then draw together the many ways that nature’s toxins affect the world,’ he says.