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Ginkgo biloba reduces incidence and severity of acute mountain sickness.


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 Pike’s 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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