It can’t just be the memorably exotic name nor the fact that
Ginkgo biloba is a beautiful ornamental tree that has made it such a
bestseller in the herbal pharmacopoeia. No, Ginkgo’s success comes from
hard-nosed clinical evidence of its benefits - as an antioxidant and
anticoagulant, but principally as a relief for the dementias of old
In Germany, where the medical system allows doctors to
prescribe herbal remedies, it’s become the treatment of choice for
Alzheimer’s disease. In fact, it’s become so popular there that,
astonishingly, German doctors now write more prescriptions for Ginkgo
than for any conventional pharmaceutical product.
It was in
Germany in the 1950s that Ginkgo was first ‘discovered’, when
botanist/physician Dr Willmar Schwabe made an extract from Ginkgo
leaves from Japan. A sacred tree to Buddhists, Ginkgo had been known to
Oriental medicine for millennia and cultivated for a variety of
medicinal purposes - from asthma to tuberculosis.
over a thousand scientific studies have been conducted, mostly in
Europe, on Ginkgo extracts, investigating its chemistry, pharmacology
and clinical effects.
>From the start, it was Ginkgo’s
effect on the brain that attracted the most interest. During 1975-1997,
40 controlled trials were conducted on patients with ‘cerebral
insufficiency’ disorders, such as senile dementia and Alzheimer’s.
Overall, these studies showed that Ginkgo could improve cognitive
function by around 25 per cent (Adv Ther, 1998; 15: 54-65).
US trial in old people’s homes had results that are typical. Over 200
patients with either Alzheimer’s or dementia due to mini-strokes were
given 120 mg of Ginkgo every day for a year. Up to 37 per cent of the
patients had significant improvements in both cognition and social
functioning - obvious enough to be noticed by the staff. Ginkgo had the
most effect in those with minor dementia but, even in severe cases, it
managed appreciably to slow down the usual rate of deterioration
(Neuropsychobiology, 2002; 45: 19-26).
Because of its lack of
side-effects (see box), some geriatricians now prescribe Ginkgo in
preference to tacrine, the only conventional drug known to benefit
dementias. Interestingly, tacrine and Ginkgo have similar effects on
brain function (Am J Ther, 1996; 3: 63-73). As a bonus, Ginkgo has also
been found to help depression in the elderly - even in cases where
conventional antidepressants haven’t worked (Geriatr Forsch, 1993; 3:
45-53). Ginkgo has also helped memory loss caused by dementia
(Psychiatr Serv, 2000; 51: 1130-4).
In the light of these
results, Ginkgo has been suggested as a possible ‘smart drug’ to
sharpen up everyone’s mental performance, not just old people’s. The
evidence for this is almost as good. A team of scientists at the
University of Northumbria carried out three separate studies on
Ginkgo’s effect on young people in their 20s. After just one dose of
Ginkgo, there were almost immediate improvements in mental ability
lasting for at least six hours (Psychopharmacology, 2000; 151: 416-23).
This ties in with research in older adults, where Ginkgo was again
found to boost mental performance, especially in people in their 50s
(Phytother Res, 1999; 13: 408-15).
The findings are not all
consistent, however. One study found that Ginkgo is 'largely
ineffective' at improving memory (Physiol Behav, 2001; 73: 659-65).
effects on the brain, particularly in the elderly, are thought to be
mainly due to the ability of the plant extract to improve blood
circulation through the brain’s tiny capillary blood vessels (Antioxid
Redox Signal, 1999; 1: 469-80). Recently, however, two further brain
actions have been found. Ginkgo has a direct action on brain
transmitters (Med Hypoth, 2000; 55: 491-3), and it has a protective
effect on neurons, particularly in the hippocampus, the part of brain
that is most damaged in Alzheimer’s cases (Eur J Neurosci, 2000; 12:
Improved blood circulation may explain some of
Ginkgo’s other benefits, too. One of the problems that people with
atherosclerosis (hardened arteries) often encounter is difficulty in
walking. Pain in the legs can build up after a few yards, but a brief
rest relieves it. The condition is called ‘intermittent claudication’.
Conventional drugs can’t provide an ‘optimal’ answer, but Ginkgo can
offer an alternative, says a recent review. Although not a cure for the
condition, it appears to be at least as good as conventional drugs -
but without the side-effects (Am J Med, 2000; 108: 276-81).
is another condition helped by Ginkgo and, here again, improved blood
circulation may be the mechanism. There’s increasing evidence that poor
blood flow in the eye is one of the causes of glaucoma. Ginkgo appears
to be the only agent capable of relieving it, with one study showing a
23 per cent increase in ocular blood flow (J Ocul Pharmacol Ther, 1999;
More exotically, Ginkgo’s effects on circulation
proved their worth to mountaineers. A Himalayan climbing expedition
conducted what is probably the world’s highest altitude clinical trial
with Ginkgo tablets vs placebos at 16,000 feet. Ginkgo proved to be a
real boon, preventing not only altitude sickness, but frostbite, too
(Aviat Space Environ Med, 1996; 67: 445-52).
Ginkgo has also
been shown to help women who suffer from premenstrual syndrome (PMS).
In a double-blind, placebo-controlled trial, French doctors tested
Ginkgo in more than 160 women with classical chronic PMS. After taking
daily Ginkgo, starting on day 16 of the menstrual cycle and continuing
to day 5 of the next, a dramatic decrease in symptoms was seen. Not
only did the women have less breast tenderness and fluid retention, but
the typical PMS mood was also improved. This decrease in
‘neuropsychological symptoms’ was objectively confirmed by the women’s
GPs (Rev Fr Gynecol Obstet, 1993; 88: 447).
In men, Ginkgo has
been touted as a cure for impotence, but when scientifically tested in
a placebo-controlled trial, this claim turned out to be a complete flop
(J Urol, 1998; 159 [suppl 5]: 240).
Products and test results
of the world’s supply of Ginkgo comes from plantations in China,
southern France and the USA. The dried leaves are turned into Ginkgo
extract, usually at a ratio of 50:1 (50 kg of leaves for 1 kg of
extract). The extract can be used in the form of tablets, encapsulated
powder or liquid tincture. All three forms are equally well absorbed by
the body (Mater Med Pol, 1995; 27: 141-6).
Of the scores of
Ginkgo products on the market - another indication of the extract’s
popularity - PROOF! has selected 12 of the leading brands for this road
As Ginkgo is made up of so many different chemical
compounds (see box above), a full product analysis is not practicable.
The herbal industry has thus agreed that certain chemical markers -
namely, the flavonol glycosides (FGs; see box above) - may be used to
indicate total Ginkgo content, as the FG content is believed to relate
to the content of all the extract’s other chemical constituents. FGs
are now generally accepted as the chief yardstick of Ginkgo potency,
with a content of 24 per cent FGs as the so-called ‘standardised’
figure. All of the Ginkgo clinical research has used preparations
containing this percentage of FGs.
Given that 24 per cent FGs
is now the universally accepted measure of quality, we rather expected
that all Ginkgo products would meet this figure, at the very least. So,
our laboratory’s analyses came as a bit of a shock, with many of these
high-street products falling below the standardised figure.
compared with abroad, consumers here seem to be shabbily treated. In
Germany, Ginkgo products contain FGs clustering around the 24 per cent
figure. Even in the unregulated USA, the manufacturers there manage to
attain that quality benchmark. A recent survey found that all the US
retail Ginkgo products tested either met or exceeded 24 per cent FGs (J
Pharm Pharmacol, 2002; 54: 661-9).
In our survey, however, a
staggering eight of the 12 UK retail products failed to reach it. Also
surprising is the discrepancy in quality among the products we tested -
with neither price nor brand reputation serving as a guide. Indeed,
some of the best-known names with the highest prices offered the
So, full marks to Lamberts, Quest and
Holland & Barrett for being up to international standards. As for
the others, if they haven’t provided a ‘standardised’ dose, they should
at least tell the consumer what percentage of FGs their Ginkgo remedies
do contain - not an onerous task as such a laboratory analysis is
simple and relatively inexpensive.
Declaring the results on
the label would help consumers make informed choices between rival
products and, more important, it would allow users to know what doses
of Ginkgo they are actually taking.
To draw up our Ginkgo
league table, our lab analysed the flavonol glycoside content of each
product, and calculated the cost of the therapeutic minimum
‘standardised’ dose of 120 mg of Ginkgo containing 24 per cent FGs, or
28.8 mg of FGs, per day.
Extra High Strength Ginkgo 6000mg
Price: £8.95 for 60 120-mg tablets
fairly high-priced product claims to provide 28.8 mg of
flavonglycosides, which works out to exactly the standard 24 per cent
FGs (in fact, the lab found the FG content to be marginally higher).
Each tablet provides the therapeutic minimum dose of 120 mg and, at 15
p per dose, is the best value for money in our road test. This is an
excellent product both in quality and price.
High Strength Ginkgo 2000mg
Price: £5.95 for 60 40-mg tablets
label states that each tablet provides 9.6 mg flavonglycosides -
precisely 24 per cent FGs - although the lab found slightly less than
that (9 mg). This is cheaper than Lamberts’ 6000-mg bottle, but you
need to take at least three tablets (at 10 p each) for a 28.8-mg FG
dose so, in fact, this would cost you more. Nevertheless, it’s a good
Ginkgo Biloba 150mg Extract
Price: £12.85 for 30 150-mg tablets
to the label, one tablet provides 36 mg of 'Ginkgo flavonglycosides',
which works out at exactly 24 per cent FGs, a figure confirmed by our
laboratory. Each tablet costs 43 p, so a standard 120-mg dose would set
you back 34 p.
Manufacturer: Nature’s Plus
Price: £11.95 for 60 120-mg vegicaps
‘Combo’ refers to the added ingredients in this product - vitamin E,
capsicum and gotu kola. Our lab analyst found the Ginkgo quality to be
quite high, with a respectable 22 per cent FGs. At 20 p per capsule,
this product should have been in pole position, but it has lost one
star because it fails to reach the FG standard.
Ginkgo Biloba 30 mg Standardized Extract
Manufacturer: Holland & Barrett
Price: £4.49 for 30 30-mg tablets
informative label tells you that each tablet contains 30 mg of 'Ginkgo
Biloba Extract, standardised for a minimum of 24% Ginkgo Flavone
Glycosides' - which turned out to be totally accurate. In fact, our
laboratory found 25 per cent FGs. So, Holland & Barrett have
produced something well up to international standards, but it’s fairly
pricey at 60 p for a 120-mg dose.
Ginkgo Biloba 520 mg
Price: £14.39 for 100 520-mg capsules
Potency Herbs' says the label from this highly reputable manufacturer.
The small print is impressive, too: 'Each Vegicaps® provides: Ginkgo
Biloba 520 mg (from ginkgo biloba leaf extract powder and 10 mg
standardised ginkgo biloba leaf extract 50:1 [minimum 24% ginkgo
Such a detailed content analysis suggests a
quality product that appears to meet the 24 per cent FG standard. But
does it? Our lab found that each capsule contains 5.6 mg of FGs -
barely 1 per cent (albeit satisfying the careful wording on the label).
So, to get the standardised 24 per cent FGs per 120 mg of
extract (28.8 mg of FGs), you would need to take just over five
capsules - at a cost of 72 p.
So, on cost alone, this would
have merited only three stars, but we’ve marked it down even further
because of the confusing label: the product does not contain a minimum
of 24 per cent FGs and is thus certainly not 'full potency'.
Price: £4.60 for 45 250-mg capsules
unpretentious, low-price product - with good reason. Our lab found only
1 per cent FGs (2.6 mg per capsule), so to obtain the standard 28.8 mg
of FGs, you would need to take 11 of these capsules and, at a cost of
10 p per capsule, that’s over £1.
Fresh Herb Extract Ginkgo Biloba
Price: £7.49 for 50 mL
liquid Ginkgo product claiming to contain 100 g of fresh Ginkgo
extract. But our laboratory wasn’t impressed. It could only find a mere
1.8 mg of FGs per mL. As the standardised dose contains 28.8 mg of FGs,
you would need to take 16 mL of this tincture to achieve a therapeutic
dose - at a rather hefty cost of £2.40.
Ginkgo Biloba 900mg
Price: £9.03 for 30 900-mg capsules
another product claiming to be 'High Potency' on the label. Certainly,
30 capsules packed with the equivalent of 900 mg of powdered raw herb
sounds like good value.
But the 'high potency' claim is empty.
Our analysis shows 5.6 mg of FGs per capsule, and you’d need to take
five to achieve the standardised 120-mg dose. This would set you back
Manufacturer: Higher Nature
Price: £8.00 for 90 30-mg tablets
reputable manufacturer with a disappointing product, but with major
claims on the label: 'guaranteed potency . . . ginkgo biloba extract
powder (standardised 24% material)'. This sounds like the real McCoy,
but our lab could detect only 0.8 mg of FGs per capsule - about 2.7 per
cent, not 24 per cent. You would need to take a stomach-churning 36
capsules to achieve a therapeutic dose, at a cost of £3.20.
Antioxidant Complex Ginkgo Plus
Price: £18.45 for 90 150-mg capsules
has a reputation as a radical but responsible manufacturer and, as a
result, has become something of a standard bearer for the alternative
Sadly, however, this product is a serious
letdown. Our lab found that these capsules contain less than 1 per cent
of FGs, a ludicrously low figure that would never get a look-in abroad.
To get the standard 24 per cent FGs per 120 mg, you would need to
swallow over 22 capsules - as well as the cost of £4.51.
Manufacturer: Higher Nature
Price: £3.90 for 30 30-mg tablets
Ginkgo product from the Higher Nature stable, this one is even more
disappointing than the more expensive product. Again, the label claims
that it contains 'standardised extract', but our lab could detect
barely 1 per cent FGs. You’d need to consume 72 tablets in one go to
get a single therapeutic dose - for a whopping £9.36.
Research on dementias in the elderly has shown beneficial effects
with Ginkgo at doses ranging from 120 mg to 240 mg a day. The effects
may take a month to become evident and usually peak two months later
(Curr Ther Res, 1998; 59: 881-8).
In younger people, a single
dose in the morning has been shown to produce improved mental
functioning for the rest of the day. The minimum dose appears to be 120
mg, rising to 360 mg - although, paradoxically, the higher doses may
cause impairment of some cognitive tasks (Psychopharmacology, 2000;
In terms of safety, Ginkgo seems to be one of the
most benign herbal remedies around. Most studies have shown that its
side-effects are minimal (Altern Ther Health Med, 2001; 7: 70-87).
However, problems may arise if Ginkgo is taken at the same time as some
prescription drugs. The blood-thinning drug warfarin should be avoided,
as Ginkgo is itself a natural anticoagulant. Ginkgo also interacts with
thiazide diuretics and the antidepressant trazodone (Drugs, 2001; 61:
What is Ginkgo biloba made of? Pharmaceutical companies have
studied the plant’s chemistry intensively, hoping to discover a key
active ingredient. But they’ve failed. One reason is that there are
over a hundred different chemicals in Ginkgo. Also, as with many other
herbs, the compounds appear to act synergistically. They have a greater
medicinal benefit when combined than when separate - the whole is truly
greater than the sum of its parts.
The biggest group of
chemical compounds in Ginkgo are the flavonol glycosides (FGs), the
chemicals that give the leaves their yellow colour. These FGs are the
main source of Ginkgo biloba’s powerful antioxidant and free
Another group of constituent
chemicals are the terpenes, the most important of which are the
ginkgolides and bilobalides. These compounds, unique to Ginkgo, are the
ones which decrease blood viscosity (‘thickness’) and so improve
circulation. In particular, ginkgolide B has been shown to have
powerful inhibitory effects on platelet activating factor, the key
component required to make the blood clot.