Its fruit is held in reverence and for centuries the tree has been regarded as
a gift to the city of Athens from the goddess Athena. But in modern Greece,
a health craze for olive leaves is causing rising hysteria that has already
resulted in one death.
Suggestions on a television chat show that consuming extract of olive leaves —
a bitter, dark-green fluid — can lower cholesterol and fight cancer have led
to a frenzied effort by Athenians to get hold of the leaves. Last week the
Greek health ministry was forced to call for calm, and a row between two
brothers over whether to give a third brother with cancer the supposed
miracle cure ended with one stabbing the other to death.
It seems that the furore stemmed from discussions on Greek television about
results of a small-scale study into the effects of the gloopy green drink
(made by boiling and blending the leaves) on mice with cancer that was
conducted at the University of Athens. The Government has given warning that
there have been “no tests on the toxicity levels of olive extract and it is
possible that it contains hazards”, and an eminent cardiologist, the former
health minister Dimi-tris Kremastinos, is urging people not to listen to the
“charlatans” talking up the benefits of the plant because “chewing the
leaves does nobody any good”. Yet the olive-leaf market is booming, with
patients prepared to pay up to £40 a kilo in health shops or stripping the
leaves from the olive trees that line the streets of Athens.
Proponents of the olive-leaf theory argue that the claims amount to far more
than a passing fad. Olive leaves have long been hailed by naturopaths as a
tonic for ailments including the common cold, arthritis, eczema and asthma.
In the early 1900sresearchers discovered a bitter phytochemical compound
called oleuropein in the leaves of certain olive trees which proved to be
partly responsible for the trees’ powerful resistance to diseases. Since
then the active compounds have been shown in small trials to possess
antiviral, antibacterial and antifungal properties effective in the
treatment of many conditions for which antibiotics and other conventional
medications have been found to be ineffective. Thirty years ago Italian
researchers showed that oleuropein could be used to lower blood pressure in
animals, and it has since been used widely by practitioners of herbal
medicine to treat cardiovascular problems.
“Their use is certainly not new,” says Dr Anne Walker, a herbalist and
researcher in human nutrition at the University of Reading school of food
biosciences. “Olive-leaf tinctures, made by steeping the leaves in alcohol
at room temperature, are often used by registered herbalists as a treatment
for cardiovascular problems including lowering of blood pressure and
cholesterol. There is also some evidence that they have an antidiabetic
effect in susceptible people.”
Although they are by no means conclusive, the cancer claims are not, it seems,
without foundation either. Last July the results of a trial carried out at
the Australian Centre for Complementary Medicine Education and Research
(ACCMER), a joint venture between Southern Cross University in New South
Wales and the University of Queensland, were published. They suggested that
olive-leaf extract in supplement form (as capsules or granules) could ward
off some forms of the disease.
Dr Lesley Stevenson, the principal researcher from the Southern Cross natural
products pharmacology unit, says that early laboratory tests seemed to
indicate that the antioxidant-rich oil from the leaves “can destroy human
breast and prostate cancer cells”. The researchers plan to carry out further
investigations to find out exactly how lethal olive leaves are to cancer
cells.
While the high levels of monounsaturated fats in olive oil (made from the
crushed or pressed fruit) mean that it is good for the heart, the leaves of
the plant have been shown to provide ten times more disease-fighting
antioxidants. Studies by ACCMER in 2005 found that olive leaves have five
times the antioxidant capacity of vitamin C and almost double that of green
tea or grapeseed extract. According to Dr Stevenson, her team also
discovered that extract of olive leaf was more powerful at getting rid of
damaging free radicals than such acclaimed antioxidants as grapeseed extract
and vitamin E — and that furthermore it could help to fight some
inflammatory conditions.
Cancer charities do not dismiss these findings but are understandably treating
the olive-leaf research with some caution. “Studies into any potential
anticancer properties of olive-leaf extract are at an extremely early
stage,” says Sue Green, a nurse with the charity Cancerbackup. “Many more
years of research are needed to see if this will ever become an actual
treatment for people with cancer.”
Dr Julie Sharp, of Cancer Research UK, says that “while a few small laboratory
studies have suggested that extracts from olive leaves might have anticancer
properties, there is still not enough evidence to confirm these
observations”.
But that evidence could become more convincing as the results of new studies
emerge. Clinical trials at the New York University school of medicine found
the natural extract to be effective against HIV without being toxic to
uninfected cells, and further investigations are planned.
Meanwhile, those seeking the health tonic who don’t wish to make their own tea
from the pale-green leaves — see below — can opt to take olive-leaf
extract as a supplement or a liquid (both are available from health stores
or online). Manufacturers such as Olive Leaf Australia recommend taking a
teaspoonful of the liquid three times a day with food, adding that it can
also be applied topically to help to heal wounds.
Cosmetics manufacturers are also beginning to add olive-leaf extract to their
products on the premise that it has antibacterial properties and helps to
soothe the skin. The Johnson’s Baby Natural range contains it, as does
Simply Organic hair and scalp wash.
Others remain steadfastly sceptical about the leaves’ beneficial effects. “The
anticancer claims appear to be based on the fact that the leaves are high in
antioxidants — and the best way to boost your intake of these compounds is
through ordinary fruit and vegetables,” says Bridget Aisbitt, a nutrition
scientist with the British Nutrition Foundation. “If your diet is
sufficiently varied you don’t need to resort to nutritional fads, which are
sometimes as harmful as they are helpful.”
How to make tea from olive leaves
Boil two quarts of water, then place 10g of olive leaves (alone or mixed with
other herbs/teas) in an infuser or directly into the boiling water.
Immediately reduce the heat to a high simmer and allow the tea to brew for
about 15 minutes. Stir the tea occasionally, then strain to drink and/or
refrigerate. The tea should be a medium amber colour with a slightly bitter
taste. To combat a specific ailment, sip the refrigerated or reheated tea
and consume the entire two quarts over the course of three days.
Olive-leaf tea: looks good, smells good, tastes weak
Olive oil is one of the great staples in life and finds its way into almost
everything I cook, as well as my bath (it’s very good for dry winter skin).
People with an interest in nutrition have made claims for the health benefits
of olive oil for many years, but I’ve never heard of the leaves being a part
of it.
Do they really have cancer-fighting properties if liquidised with water and
taken as a drink? I doubt it. It seems to me a lot like the wheatgrass
thing: mix up a revolting gloop, tell people it’s good for them and watch
the money roll in.
That said, I was happy to give it a go. The tisane was surprisingly pleasing.
On a day when I felt like death (revolting cold and chest infection), I
chucked a handful of leaves into a pan of boiling water, allowed to simmer
for ten minutes, then poured.
Hmm. It had a wonderful golden colour, a lot like good extra virgin olive oil
but without a trace of actual oil. Yet it had a ghostly viscosity, as though
the spirit of the oil were in the leaves. It smelt delicate and tasted like
very weak green tea (I imagine it would be nice with a slice of fresh ginger
in it). I drank a whole pot and felt rather better, though that might just
have been the Nurofen Plus-Panadol Extra cocktail kicking in. Nevertheless,
it was much nicer than chamomile tea — although, I suspect, no more
effective at kicking cancer.
Sarah Vine
