Nutrition Science News
By Richard N. Podell, M.D.
Ginkgo seems to increase blood flow to the brain,
improving oxygen and glucose supplies while enhancing cognitive
There is reason for celebration among
proponents of natural healing, and the guest of honor is ginkgo.
Recent research results may finally convince U.S. physicians to
seriously consider natural treatments.  It isn't because there
wasn't evidence to support ginkgo as an effective treatment for
dementia (declining mental power), but the evidence, until now,
was not the kind U.S. physicians took seriously.
More than a dozen double-blind studies have shown that ginkgo can
reduce mental decline. [2-5] Those studies did not, however, pierce
the armor of our old medical paradigm--that only drugs and
surgery are effective treatments for disease. Those double-blind
studies were suspect in part because they were done in Europe and
published in workaday journals, not the elite publications where
paradigm-busters should appear.
Now, that has changed. The recent ginkgo study was done in the
United States. It appeared in the Journal of the American
Medical Association, a publication that ranks high in
prestige and readership.
The bottom line is this: Ginkgo surpassed placebo for the
treatment of Alzheimer's dementia. It is definitely not a cure,
but it probably works as well as any drug that has been tried.
And crucially, for this fragile group of patients, side effects
Ancient Chinese Secret:
Ginkgo biloba is the world's oldest species of tree; its
ancestors date back 200 million years. Ginkgo is native to China,
where it is considered a sacred tree. In traditional Chinese
medicine, ginkgo is believed to benefit the brain. In Germany and
France, where ginkgo is prescribed like a drug, ginkgo leaf
extract accounts for more than 1 percent of drug sales. 
Ginkgo seems to increase blood flow to the brain, improving
the supply of oxygen and glucose. At the cellular level, ginkgo
stabilizes membranes, scavenges toxic free radicals, stimulates
enzymes that relax arterial muscles and inhibits blood platelet
For their study, researchers at the New York Institute for
Medical Research in Tarrytown, N.Y., recruited more than 300
patients who had mild to moderate dementia as measured by two
standard tests, the Mini-Mental State Examination and the Global
Deterioration Scale. The majority of patients had Alzheimer's
disease. About one-quarter had multi-infarct dementia caused by
Three times a day patients received either a placebo or 40 mg of
EGb 761, a standardized ginkgo extract that is available in
Europe and the United States. Outcomes were carefully measured
using three standard tests. Two measured memory, thinking skills
and day-to-day function--the Alzheimer's Disease Assessment Scale
(ADAS-Cog) and the Geriatric Evaluation by Relative's Rating
Instrument (GERRI). One measured general psychological
adjustment--the Clinical Global Impression of Change (CGIC).
Patients were examined 12, 26, 39 and 52 weeks after starting the
For the ADAS-Cog test, the average score for the placebo group
declined, whereas the ginkgo group score remained stable. The
advantage of ginkgo compared to placebo was statistically
significant. Of patients on ginkgo, 50 percent improved by two
points or more, while only 29 percent improved on placebo.
On the GERRI test, the ginkgo group improved while the placebo
group worsened. The difference favoring ginkgo was highly
significant, with the probability that the result was due to
chance being less than 0.004. Of patients in the ginkgo group, 37
percent improved and 19 percent became worse. The placebo group
showed an opposite trend: 40 percent worsened and 23 percent
improved. Thus, both tests of cognitive and social function
showed improvement for patients on ginkgo compared to placebo.
On the CGIC, which measures general psychological adjustment,
both groups stayed about the same. This was not surprising
because the CGIC is not a sensitive measure of dementia status.
Adverse events were few. There was a small increase of incidence
of gastrointestinal symptoms among patients taking ginkgo.
Overall, this was a careful, rigorous study. The authors analyzed
the results to identify factors that might call the study's
results into question. For example, as might be expected among
patients with dementia, drop-out rates were high. Only 38 percent
of the placebo patients and 50 percent of ginkgo patients
completed the full year of treatment. Statistical analysis from
each interval visit, however, suggests that the high drop-out
rate should have made it harder to measure the positive effect of
ginkgo. So the benefit of ginkgo might be even greater than it
Noncompliance, or failure to take all medicine doses, might
affect results. Again, this would be expected to obscure, not
enhance, the ability of ginkgo to perform better than placebo.
Subgroup analysis showed ginkgo was effective both for the entire
group and for the three-fourths of patients who suffered from
Alzheimer's. There were not enough patients in the multi-infarct
dementia group to show a statistical benefit for ginkgo compared
The conclusion: Ginkgo was better than placebo for treating
Alzheimer's dementia. It stabilized performance during a year,
and in a substantial minority of cases led to improvement. The
treatment was safe; side effects were minor. We cannot yet say
whether ginkgo is also effective for multi-infarct dementia.
Will ginkgo soon be considered conventional? It is too early
to tell, but the odds look encouraging.
Will the success of ginkgo encourage acceptance of other
natural treatments? I wouldn't be surprised. Perhaps good
practice will soon require that patients be informed of
ginkgo as a treatment option.
Will drug companies trump the natural products industry by
identifying the active biochemicals in ginkgo, then patenting and
selling them? Not for a while, but I hope they try. That kind of
competition increases our knowledge and creates legitimacy that
will make ginkgo better known. More likely, though, the whole
herb will prove to work better than any one of its parts--after
all, that is how nature evolved it to function.
Ginkgo, of course, is just one herbal medicine whose sales have
expanded phenomenally in recent years. For people who want to
learn more about this newly exciting field, I recommend two
books. As a physician, I value Botanical Influences on
Illness by Melvyn Werbach, M.D., and Michael Murray, N.D.
(Third Line Press, 1994). For a skeptical but open-minded
mainstream point of view, try Varro Tyler's classic book,
Herbs of Choice (Pharmaceutical Products Press, 1994) or
his earlier work, The Honest Herbal, 3rd Edition
(Pharmaceutical Products Press, 1993).
Richard N. Podell, M.D., is clinical professor of
family medicine at the UMDNJ-Robert Wood Johnson Medical School
in New Brunswick, N.J., and director of the Podell Center for
Medical Treatment, Prevention and Natural Healing in New
1. LeBars, P., et al. "A placebo-controlled,
double-blind randomized trial of an extract of ginkgo biloba for
dementia." JAMA, 278(16): 1327-32, Oct. 22/29,1997.
2. Kanowski, S., et al. "Proof of efficacy of the
ginkgo biloba special extract EGb 761 in outpatients suffering
from mild to moderate primary degenerative dementia of the
Alzheimer type or multi-infarct dementia." Pharmacopsychiatry,
29: 47-56, 1996.
3. Kleijnen, J., et al. "Ginkgo biloba for cerebral
insufficiency." Brit J Clin Pharma, 34: 352-58, 1992.
4. Letzel, H., et al. "Nootropics." J Drug Devel
Clin Practice, 8: 77-94, 1996.
5. Hofferberth, B. "The efficacy of EGb 761 in
patients with senile dementia of the Alzheimer type, a
double-blind placebo-controlled study on different levels of
investigation." Human Psychopharmacology, 9: 215-22, 1994.
6. Werbach, M., & Murray, M. Botanical
Influences on Illness: Tarzana, Calif.: Third Line Press,