Quercetin prophylaxis in prevention of acute mountain sickness (AMS): a randomized, double blind, placebo controlled phase-II clinical trials.

BACKGROUND

Acute Mountain sickness (AMS) is a common form of high altitude illnesses (HAI) primarily caused by hypobaric hypoxia. Proper acclimatization is crucial for enhancing the physiological adaptability during ascent to high altitudes (HA).

AIM: The present study aimed to evaluate the effectiveness of quercetin bar prophylaxis in preventing AMS during acclimatization to a high altitude environment.

DESIGN

A double blind, randomized, placebo-controlled trial.

METHODS

The study included 110 healthy lowland male subjects with age 26.86 ± 4.1 years (range between 20 and 40 years), who ascended from near sea level (440 m) to high altitude (3048 m) where they spent 6 days, thereafter further ascended to very high altitude (3750 m). The participants were randomly assigned in to two groups. Placebo group (n = 55, food bar without quercetin; identical in appearance, taste and smell) and Quercetin group (n = 55, food bar containing 500 mg quercetin). Subjects consumed one bar daily for 15 days, beginning two days prior to ascent and continued throughout the study period. Physiological parameters (SpO2, pulse rate, blood pressure), physical performance (six minute walk test), hematological variables (haemoglobin and haematocrit) and biochemical parameters were assessed at three different points i.e. at baseline (sea level), day 7 (at high altitude) and day 15 (at very high altitude). AMS incidence and severity were evaluated using the Lake Louise Scoring (LLS) system.

RESULTS

Quercetin supplementation significantly reduced the incidence and severity score of AMS compared to placebo. At the end of the study, AMS prevalence was 2% in the quercetin group versus 25% in the placebo group. Arterial oxygen saturation was significantly higher in the quercetin group (94.0 ± 2.0%) compared to the placebo group (90.02 ± 1.0 p < 0.001). Both systolic (8 mm Hg) and diastolic (4 mm Hg) blood pressure were significantly lower in the quercetin group (p < 0.001). Hematological parameters (haemoglobin and haematocrit) showed improvement with quercetin supplementation. Oxidative stress parameters indicated reduced malondialdehyde (MDA) levels (p < 0.001) and maintained reduced glutathione (GSH) levels in plasma of quercetin group. Plasma endothelin-1 (ET-1) levels were significantly reduced in the quercetin group (p < 0.001). No significant differences were observed in body composition parameters (body weight, fat mass, fat percentage and percentage of total body water) between the groups.

CONCLUSION

Prophylaxis with quercetin bar appears to be effective in reducing the incidence and severity of AMS. It also improves the physiological and haematological responses along with reducing the oxidative stress of the individual ascending to high altitudes.