While a few plants can be used to cure disease, most are only effective as placebos, according to an expert
‘PLANTS HAVE been trying to kill us, not cure us,” says Dr Henry Oakeley, the garden fellow at London’s Royal College of Physicians.
Not a comment you might expect from a man who oversees a garden of 600 plants used in medicine for 3,000 years, a man you’d expect to extol medicine’s indebtedness to the plant kingdom.
In Dublin to open a medicinal garden at Trinity College to mark 300 years of botany at the college, he’s well aware that his “very anti-herbal medicine” stance and will jar with some.
“I [nearly] got lynched when I gave this lecture at a herbal medicine conference,” says the former physician and psychiatrist, who is passionate about botany.
But if plants are, for the most part, as medicinally useless as he believes, how does he explain their centrality to the beliefs and practices of medical practitioners for centuries?
“Because they believed in the tooth fairy,” he says matter of factly. “They had no concept of illness or of chemistry or biochemistry. They believed all plants had been put on the earth by the creator for mankind’s use. So if the plant had a particular shape, it indicated that the creator had put it on the planet for a particular use.”
Citing as an example the use of blue liverwort, Hepatica nobilis, once cultivated as a liver tonic because its three-lobed leaf form mirrored the shape of the liver, he says, "It was absolute rubbish. They had no idea how the body worked."
In the 1880s, at the height of its popularity, those taking it to cure feelings of “liverishness” were stuck down by jaundice because the plant was in fact toxic to the liver.
“The basic concept that most people have missed is that [many] plants are poisonous,” he says. “We just have to find a way of using the poisons in plants to our advantage.”
While early doctors may have had little concept of how things worked in the body, the effects of plants on the brain were more observable.
“Opium for example: if you take a little you feel happy, a bit more and you are disinhibited, more and you start to fall asleep and feel no pain. So it was used as a painkiller from very early on,” he says.
Early physicians knew also that deadly nightshade, more commonly known as belladonna, was fatal.
“But if you took a small dose, you would hallucinate, have a dry mouth and dilated pupils – hence the name “belladonna” – and you’d become unconscious so a doctor could do things like amputate, or cauterize wounds.”
However, Oakeley dismisses suggestions of belladonna’s efficacy as a modern-day homeopathic remedy. He says the fact that a plant may have been used in medicines for thousands of years doesn’t lend such claims any more weight.
“In most cases it’s been a myth from day one,” he says. “Homeopathic medicine is a complete fairy tale. To a put a molecule of a chemical into gallons of water: there’s no reason why it should work. The only response you get from homeopathic medicines is a placebo response.
“It [a homeopathic remedy] may do good [through this] placebo effect . . . if you have a good homeopath, his or her placebo response will be better than just drinking water.”
Of the peonies in the garden at his place of work, he says, roots hung around the neck were regarded as a cure for epilepsy by Galen as far back as AD 200, with the plant cropping up again in a 1737 book called A Curious Herbalas a cure for febrile fits in teething children.
“Nailing a brick to a wall would have been just as effective,” he remarks. “Febrile fits are self-limiting and will stop when the fever subsides anyway.”
However, he concedes that some plants used by the ancients did have curative properties – and continue to have a place in medicine today.
Used in Egypt for centuries to treat renal colic, khellin, a member of the cow parsley family, was found in the 1920s to cause dilation of the urethra and the coronary arteries. As a result of the discovery, drugs have been developed that treat angina and cardiac arrhythmias today.
A 16th-century GP William Withering found that a patient of his was cured of dropsy (heart failure) after taking foxglove leaf prescribed by a herbalist. A chemical extracted from foxglove leaf is now the source of the modern day cardiac medicine digoxin.
A more recent example is the plant Chinese star anise, the seedpods of which are used to make shikimic acid from which Tamiflu, the treatment for bird and swine flu, is made.
Nevertheless, he says, the number of plants that have evolved from herbal medicine to real medicine is tiny. “The thousands of years of plants being used as medicines have actually taught us very little.”
Welcoming forthcoming UK legislation that will be stricter on the prescription of herbal medicines, he says the claims by some that they have fewer side effects are misleading.
St John’s Wort, for example, a herbal remedy used for depression, can work by blocking the destruction of serotonin, he says – and side effects include the possible inactivation of the heart drug warfarin, oral contraceptives and HIV treatments.
“Herbalists say these things are pure and don’t have the same side effects as Prozac, [but] they have other side effects . . . That’s the problem with herbal medicine, there is no proper long-term check on the side effects.
“People have faith in herbal medicine and if you have faith in something then it has an effect. The only thing wrong with [herbal medicine] is that it may have a side effect. Also, you may not be treating the illness.”
Oakeley is cognisant of the fact that his own view of medicine also represents a moment in time.
“In 60 years’ time, our current medicines will seem as rudimentary as peony root . . . just as we [currently] treat pneumonia by treating the bacteria that causes it, we will treat diseases like cystic fibrosis, schizophrenia and Alzheimer’s by treating the gene which causes them.
“I promise you, in 50 to 100 years’ time, people will be as rude about most of the medicines we take today as I am about peony root.”
For more information, see tcd.ie/botany
