Ginkgo biloba does--and does not--prevent acute mountain sickness.

Objective. - To determine the efficacy of 2 different sources of Ginkgo biloba extract (GBE) in reducing the incidence and severity of acute mountain sickness (AMS) following rapid ascent to high altitude. Methods. - Two randomized, double-blind, placebo-controlled cohort studies were conducted in which participants were treated with GBE (240 mg-d-1) or placebo prior to and including the day of ascent from 1600 m to 4300 m (ascent in 2 hours by car). Acute mountain sickness was diagnosed if the Environmental Symptom Questionnaire III acute mountain sickness-cerebral (AMS-C) score was ≥0.7 and the Lake Louise Symptom (LLS) score was 23 and the participant reported a headache. Symptom severity was also determined by these scores. Results. - Results were conflicting: Ginkgo biloba reduced the incidence and severity of AMS compared to placebo in the first but not the second study. In the first study, GBE reduced AMS incidence (7/21) vs placebo (13/19) (P =.027, number needed to treat = 3), and it also reduced severity (AMS-C = 0.77 ± 0.26 vs 1.59 ± 0.27, P =.029). In the second study, GBE did not reduce incidence or severity of AMS (GBE 4/15 vs placebo 10/22, P =.247; AMS-C = 0.48 ± 0.13 vs 0.58 ± 0.11, P =.272). The primary difference between the 2 studies was the source of GBE. Conclusions. - The source and composition of GBE products may determine the effectiveness of GBE for prophylaxis of AMS.