Eat me if you dare: Humans and plant medicine

It’s a love / hate / kill relationship…

Many household medicines are derived from plants [Image by author]
 Walls bedecked with innumerable shelves, each crammed full with medicines. The latest blockbuster cure behind the counter. While the pharmacist attends to another customer, a mother warns her feverish child not to touch the item he’s been eyeing on the display stand.  The year is 1640, and this Peruvian apothecary has just received a new shipment of Quina bark – the latest weapon in the fight against Malaria. The bark contains quinine (now found in supermarkets worldwide as the flavouring in tonic water) an alkaloid that kills the malaria blood parasite when the dried bark is crushed and drunk. The boy’s fever will soon disappear, and a thankful mother waits patiently for medicine she knows will work. As successful as Quina bark was, humans haven’t always been right when it comes to ‘Nature’s remedies’.

Packing a punch…
Plants, unable to move, have had to come up with some pretty powerful methods of keeping predators at bay. One of these is to create and store potent chemicals (such as caffeine, nicotine, cocaine and morphine). The idea is that even a nibble of the plant is enough to send the would-be herbivore in search of safer, tastier food. It seems to have the opposite effect on humans though; the powerful chemicals that plants create only draw us nearer (as with the examples above). These chemicals can fight a plant’s predator in many ways; there are those that are antimalarial, antibacterial, nervous system depressants, enzyme inhibitors, heart rate stimulants, and psychedelics to name a few. And in the right dose, all of them can kill.

Since ancient times people have looked for drugs in nature, and only with experience found the delicate balance between healing and death. Yet with some plants, there is no such balance. The history books show that humans have long recognised the power that plants possess.

Image credit: Andrea Parrish-Geyer via flickr

They’re in your pantry!
Many spices in our pantries were first used for medicine before they became household flavourings. Notable drugs-come-food are mustard, mace, chilli, wasabi, vanilla, fennel, dill, ginger, and saffron. Some, like turmeric, are still being investigated today.

Around 1470 BC, the Queen of Sheba sent an expedition out to retrieve exotic plants, riches and spices to bring back to Egypt as a tribute to her gods. When the expedition returned they brought with them ivory, ebony, gold, animal skins, incense and various spices from distant lands. One of these spices was nutmeg, which contains the chemical compound eugenol. It was – and still is – considered an aphrodisiac; capable of arousing any who consume it. In India, a thousand years before the Queen of Sheba’s time, it was already a part of the medicinal and culinary flora and its hallucinogenic and stimulating effects were well known.

Eugenol is also found in cinnamon and cloves (which both contain a suite of other active substances), giving a different spin to the term ‘festive’ spices.

We’re hardwired to detect poison

There are many different types of plant toxins – the majority of which are bitter. As it turns out, as children we have hypersensitive bitter taste receptors, which diminish as we develop towards adulthood. Without our parents’ experience, and in the age prior to supermarkets, the ability to detect bitterness would have saved many young lives. But don’t let your guard down! Many household foods come from toxic plants; tomato, eggplant, rhubarb and potato plants all have poisonous leaves. Although present in such small quantities that it would take a few kilos of leaves to kill you, consumption of these can still cause quite a lot of discomfort (like nausea and vomiting).

During food shortages in World War I, the British government actually advised people to eat rhubarb leaves. Needless to say, this lead to few cases of poisoning – and in one case death.

Looking forward…

On land alone there may be up to 300,000 unidentified plant species, and the ocean’s flora is almost completely unknown. Because of this, there’s a lot of interest in land and marine bioprospecting. But who knows, it may be lurking in your pantry…

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5 Responses to “Eat me if you dare: Humans and plant medicine”

  1. Runjie Yuan says:

    Interesting article. Before the advent of modern medicine, I think people can only know the use of plants by experience. They must have tried lots of different plants to identify if they are useful, useless or even poisonous.
    Hail to the intrepid pharmacists and patients who were at high risk of losing their lives in the tests.

  2. kkhine says:

    It is interesting. Ginger, turmeric are ingredients of curry in my country (Myanmar).

  3. Tal Cohen says:

    @Arun, check out the book I added at the bottom of the post. It’s got quite a bit on hallucinogenic plants and their use by different cultures/religions.

    @bwolfaardt and Arun, I’d also love to know. But humans have a habit of exploiting natural resources and destroying ecosystems for our own benefit, so I’m a bit ambivalent about it.

  4. bwolfaardt says:

    Great post. I found that really interesting particularly the fact that some of my favourite fruits and vegetables have poisonous leaves – I had no idea.

    I’m with Arun, it would be interesting to see what’s hiding in the ocean.

  5. How interesting.

    When I visited Peruvian amazon a few months ago I saw some interesting plant substances in a marketplace used by traditional healers/shamans as medicines. They included the ingredients used to make a psychoactive brew called ayahuasca. Many of the travellers I met were visiting to take traditional medicines, particularly ayahuasca. The brew is said to induce vomiting (poison?). One of the shamans and a couple of travellers I talked to also said they used a secretion from toad skins (bufotenin presumably) which induces nausea.

    I wonder what interesting psychoactive bioprospects, medicinal or otherwise are hiding among the ocean’s flora.