So that got me and Haseena thinking, what actually causes altitude sickness? We all know that at a higher altitude, the air pressure is lower. This makes it more difficult for oxygen to travel through our lung membranes and into our blood. Your blood becomes oxygen-deprived, a condition called hypoxia.
Hypoxia has several negative consequences. The immediate ones are obvious: a sharp increase in pulse and blood pressure to account for the heart working significantly harder to pump more oxygen into blood cells. This results in the fatigue, increased heart rate, and shortness of breath -- all symptoms of acute altitude sickness.
If you stay at a high altitude for a longer period of time, though, this oxygen deprivation will inflict actual damage. Turns out, antioxidants are involved (seriously, when aren't antioxidants involved?). A state of hypoxia causes the level of reactive oxygen species (ROS) in the body to increase drastically. ROS are basically free radicals with oxygen as their center, such as a hydrogen peroxide radical or hydroxyl radical. These ROS are produced normally in the body's natural metabolism of oxygen, but at high altitude, the level of free radicals in our blood is higher than our natural level of antioxidants. Also, antioxidant activity is reduced at higher altitudes. Therefore, the reactive oxygen species are free to wreak havoc on our bodies by causing severe oxidative damage, including peroxidation of lipids, fragmentation of DNA, and damage to proteins along with other macromolecules. This damage to cells from oxygen-based free radicals is called oxidative stress. This loss of functionality leads to nausea, dizziness, and even brain dysfunction (you can't think clearly or have blurred vision).
The body's natural emergency reaction to oxidative stress is to produce more red blood cells and capillaries at the lung/vascular system interface, in addition to increasing lung size to allow a greater area for oxygen to be transported to the blood. (Fun fact: this is why Olympic athletes train in Colorado. They will physically have a greater lung capacity from spending time at such a high altitude.) However, this usually takes longer to accomplish than the time it takes for us to feel the negative effects of newly formed free radicals. The best thing you can do is to descend to a lower altitude.
There have been claims that taking antioxidant supplements such as vitamin C and vitamin E will reduce the effects of altitude sickness because they will neutralize the excess oxygen reactive species. For example, climbers of Mt. Everest take intense daily doses of antioxidants.
Who knew that altitude sickness is linked to free radicals? Just another chapter to add to the "Antioxidants Cure Practically Everything" book.
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