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Ginkgo
biloba reduces incidence and severity of acute
mountain sickness.
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Kirsten
Maakestad, MD, Gig Leadbetter, PhD, Sheryl Olson, RN
and Peter Hackett, MD
Context:
Two Himalayan studies found Ginkgo Biloba prevented
Acute Mountain Sickness (AMS) during gradual ascent.
Objective:
To determine the effectiveness of prophylactic Ginkgo
Biloba on incidence and severity of AMS during rapid
ascent.
Design:
Double-blind, placebo-controlled cohort study. The two
groups were matched for age, gender and rate of
ascent.
Subjects:
Forty college students residing at 1400 m (4,597 ft.).
Intervention:
Subjects received either Ginkgo Biloba 120 mg orally
or a placebo twice a day, starting five days prior to
ascent of Pikes Peak (2 hours by vehicle to 4300 m
[14,110 ft.]) and continued while at elevation
overnight.
Primary
Outcome Measures: ESQ-III (short form) and Lake
Louise Score (LLS) completed before ascent and at
altitude, either 24 hours after ascent or when removed
from the study because of symptoms. Both ESQ
> O.7 and LLS > 3 were required for AMS.
Results:
Ginkgo reduced incidence of AMS (7 of 21 with
AMS vs. 13 of 19 with AMS, ginkgo vs. placebo, p<
0.02). Ginkgo also reduced severity of AMS by both
scores (mean ESQ = 0.77 + 0.20 vs. 1.59 + 0.32, ginkgo
vs. placebo, p = 0.03; mean LLS = 3.9 + 0.6 vs. 6.2 +
0.9, p < 0.05). SaO2 was inversely correlated
with severity of AMS; age, gender, and hematocrit did
not relate to AMS.
Conclusion:
Ginkgo Biloba taken five days prior to rapid ascent to
4300 m reduced both incidence and severity of AMS.
Speculation:
Ginkgo biloba inhibits inducible nitric-oxide synthase
(iNOS) and also scavenges oxygen radicals; one of
these actions might explain its effectiveness in
preventing AMS.
In
"Peter's words"....
Ginkgo
looks like it might be quite useful. The dose used by
the French was 80 mg twice a day. We used 120 mg
twice a day, only because we had 60 mg tabs, and they
couldn't be divided in half to get 80 mg per dose.
So it doesn't matter much - 80 to 120 mg twice a day.
As with all drugs, probably better to use a lower dose
than a higher dose, if both doses work. So far,
it's only been studied starting 5 days before getting
to high altitude. It could probably be taken a
day before ascent and still work, and it might even
work after one gets symptoms of AMS, but we don't yet
know - that will take further research. It's
essentially harmless, but
it does "thin the blood" a bit (interferes
with platelet activity) and should therefore be
avoided by those taking anticoagulants, Vit E, and
maybe those taking aspirin or NSAID's, but it's not
clear about the NSAID's.
Also, since Ginkgo isn't controlled by the FDA, a
consumer never knows exactly what he/she is getting.
For the best products and results of testing, see www.consumerlabs.com.
I
don't yet know how Ginkgo works. As you probably
know, it has been proven useful for dementia and some
other neurological problems. As for AMS, it
could act by a couple different ways. One is to
block the enzyme inducible nitric oxide synthase (iNOS),
which produces nitric oxide (NO). We measured
iNOS in our study on Pike's Peak, and on Denali, but
we don't have the results back yet - had to send the
blood to Australia. NO is a factor that can
cause the blood-brain barrier to leak, and may be what
causes the brain edema. Ginkgo also is an oxygen
radical scavenger, which means it is a type of
anti-inflammatory, and to the extent that the leak in
the brain during AMS is inflammatory (some think it
is), it could work this way. Ginkgo also
inhibits platelet activating factor, but I don't know
if this would be helpful or not. In short, I don't
know how it works, but we're trying to figure it out.
You
might also be interested to know that Ginkgo really
helps peripheral blood flow in the cold, and at high
altitude. In fact, in the French study, there
was a marked increase in hand blood flow in the
subjects on ginkgo compared to placebo, and those on
Ginkgo had far fewer problems/complaints due to cold
hands and feet. We didn't measure that in our
Pike's Peak study.
Bottom
line as far as I'm concerned: Ginkgo needs more
research, but there is sufficient data to test it for
both adjusting to altitude and to cold. It's not
a miracle drug, but it will help reduce the incidence
and severity of AMS (not HAPE). It's safe,
non-prescription, cheap. I would especially recommend
it for those situations in which I might consider
Diamox: abrupt ascent, past history of AMS, and those
who really need to avoid AMS for various reasons, like
diabetes, lung disease, maybe pregnancy, etc. If
it didn't work, and Diamox was felt necessary, no
problem, you could give Diamox. Peter Hackett, MD
Note:
You should consult your physician before taking any
drugs, other medicine, or stimulant of any kind before use.
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