Acute Mountain Sickness
Acute mountain sickness is caused by reduced air pressure at high altitudes (>8,000 feet/2,400 meters), leading to lower oxygen availability and impaired oxygen transfer to the blood. Symptoms can include dizziness, trouble sleeping, fatigue, headaches, nausea, and shortness of breath.
Acute Mountain Sickness falls under theOthercategory.The Examine Database covers Ginkgo BilobaandAlpha-Lipoic Acidinterventions.
Last Updated:February 7, 2025
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In this meta-analysis of randomized controlled trials, the effect of supplemental nitrate on oxygen saturation levels in high-altitude environments (simulated or real) was inconsistent.
What was studied?
The effect of supplementation with nitrate on oxygen saturation (SpO2) levels and symptoms in the context of acute mountain sickness (AMS).
The primary outcome was SpO2 levels during the following:
- Submaximal exercise in simulated high-altitude environments (i.e., in a hypoxic-hypobaric chamber)
- Rest in a simulated high-altitude environment
- Rest in a real high-altitude environment
The secondary outcomes were AMS symptoms and nitric oxide (NO) levels in a real high-altitude environment and NO levels in a simulated high-altitude environment.
Who was studied?
A total of 205 participants (192 men, 13 women) with no known health conditions.
How was it studied?
A meta-analysis of 7 randomized controlled trials was performed. The daily dose of supplemental nitrate ranged from 5 to 15 millimoles, and the intervention duration ranged from 1 to 20 days. SpO2 was measured 127 to 210 minutes after supplementation with nitrate. In most of the trials conducted in simulated high-altitude environments, the duration in the hypoxic-hyperbaric chamber ranged from 6 to 9 days. The comparator was a placebo in all of the trials.
What were the results?
Supplementation with nitrate increased (improved) SpO2 levels during submaximal exercise in a simulated high-altitude environment, but there was no effect on SpO2 levels at rest. Also, nitrate increased (improved) NO levels in both simulated and real high-altitude environments. Each analysis was conducted with just 2 or 3 trials.
The risk of bias was low in 1 trial, high in 2 trials, and unclear in 4 trials, and the certainty of evidence was low for most of the outcomes.
Anything else I need to know?
In the study abstract, the authors stated that supplementation with nitrate aggravated the SpO2 decline during rest in real high-altitude environments. However, this finding was from a sensitivity analysis that removed 1 trial and included just 2 trials.