Ginkgo protects against altitude sickness
In this study of mountain climbers on a Himalayan expedition,
extract of Ginkgo biloba L. (Ginkgoaceae) was significantly
more effective than placebo in preventing acute altitude sickness
and cold-related vascular problems [Roncin et al., 1996].
At elevations higher than 9,000 feet (3,000 meters), most people
experience some degree of altitude sickness, which can cause symptoms
such as headache, dizziness, shortness of breath, nausea and vomiting.
In addition to oxygen deprivation, people at high altitudes may
be also subjected to extreme cold. Cold-related microcirculation
disturbances can lead to numbness, tingling, aching and/or swelling
of the extremities, with a resulting loss of manual dexterity.
The controlled study involved 44 healthy climbers, all men,
who had experienced altitude sickness on previous expeditions.
The subjects were randomized into two equal groups. One group
received two tablets of standardized ginkgo extract twice a day,
a total daily dose of 160 mg, and the other took placebo. Over
a period of eight days, the climbers ascended gradually to a base
camp with an elevation of about 14,700 feet (4,900 meters), from
which they made subsequent ascents to higher altitudes. Symptoms
were recorded daily with a 67-item scale called the Environmental
Symptoms Questionnaire. Separate analyses were performed of a
number of different factors, including cerebral and respiratory
altitude sickness symptoms.
According to assessment of cerebral symptoms, none of the
climbers who took ginkgo experienced acute mountain sickness,
compared to 41 percent of those taking placebo. According to assessment
of respiratory symptoms, 14 percent of climbers in the ginkgo
group had altitude sickness, compared to 82 percent in the placebo
group. These differences were highly significant. Ginkgo was also
significantly more effective than placebo in preventing cold-related
vascular problems, based on evaluation of functional disabilities
and results of plethysmography testing (a measurement of blood
flow to the extremities). In addition, only 18 percent of ginkgo
subjects reported moderate or severe impairment of diuresis at
high altitude, compared to 77 percent of those in the placebo
group.
Interestingly, while there were no smokers or ex-smokers
in the placebo group, there were two smokers and three ex-smokers
in the ginkgo group, a factor which might have been expected to
have a negative impact on results with ginkgo. The ginkgo preparation
used in the study was EGb 761 (Tanakan®, marketed by Ipsen
of Paris, France) a concentrated extract standardized to 24 percent
ginkgo flavone glycosides and 6 percent terpene lactones.
Evelyn Leigh, HRF
[Roncin JP, Schwartz F, D'Arbigny MD. EGb 761 in control of acute
mountain sickness and vascular reactivity to cold exposure. Aviation,
Space, and Environmental Medicine 1996; 67(5): 445-452.]
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