Dehydration at High Altitudes
Higher altitudes are associated with dehydration as a result of increased urine output, dryer air and more rapid breathing, resulting in a greater loss of bodily fluids.
Furthermore, colder temperatures found at higher altitudes suppress the body’s sensation for thirst by around 40 per cent, while the kidneys conserve less fluid.
Add physical activities such as snowboarding or skiing and fluid losses through sweat can be significant yet barely perceptible because the sweat evaporates quickly in the drier air.
That dry, cold air will also absorb more moisture from the body when it is in the lungs, further contributing to fluid loss.
While eating snow may contribute to rehydration, it is not recommended when in cold conditions as it acts as a heat sink on your body and may encourage cold-related illnesses. Furthermore it has also been found that snow will absorb carcinogenic pollutants in the air, meaning you may be eating nasty chemicals.
Also worth considering is that dehydration will increase the likelihood of altitude sickness by reducing the body’s ability to acclimatise to lower oxygen levels.
While the point at which altitude sickness may become a danger begins at around 2500m above sea level – and with Mt Kosciousko being Australia’s highest point at 2228m – it is not an immediate concern for Aussies, however it is an important consideration for anyone travelling overseas.
Whether you’re climbing Mt Everest or Skiing Perisher, you might also consider drinking more tea: 2004 research looked at the effects drinking tea at high altitudes (Mt Everest base camp at 5345m) had on mood and hydration status.
In the study, 13 people were monitored during two different 24 hour periods. No difference in the hydration status of participants was found between the two periods, however subjects did report reduced fatigue when tea was included in the diet.
Those who are flying at high altitudes as a result of air travel should also consider that the humidity on planes is kept very low at around 10-20% (like a desert) which leads to increased dehydration along with tiredness, reduced concentration, dry eyes, throat and nose and potentially, respiratory infections.
Other things you can do to remain hydrated at high altitudes do not vary significantly from those healthy hydration habits at sea level, such as avoiding alcohol and sugary drinks, eating water-rich foods, and pre-emptively hydrating.