We’ve all been there.
Crawling from an aircraft after an arduous long-haul flight feeling like death warmed up and spending the next few days blaming jet lag for every debilitating symptom from lethargy and headaches to burning eyes and constipation.
But, more often than not, the culprit is simple dehydration brought on by spending hours at altitude without guzzling enough water.
For Australians heading across continents or oceans, flying means extensive stretches in an artificial environment with reduced oxygen and associated low humidity, which can plunge below conditions in an African desert, rapidly drawing moisture from the body.
Research shows that during an average 10-hour flight, women lose 1.6 litres, with closer to 2 litres for men, so flyers travelling between Sydney and London can sacrifice 4 litres or 8 per cent of body water.
Jonathan Cohen, medical director of Travel Clinics Australia, says people are prone to dehydration while flying because cabin air is depressurised and dehumidified from the usual range of 50 to 80 per cent down to 10 or 20 per cent.
“Unless extra fluids are continuously taken, the body loses a lot of water over the time of the flight and this can be compounded by drinking a lot of tea, coffee or alcohol which all have a diuretic action to increase fluid loss,’’ he says.
“Symptoms include thirst, increased heart rate, tiredness and feeling light-headed and, if more severe, can progress to nausea, mental clouding and severe malaise with fainting a natural body reflex that makes us fall in order for blood to reach the brain.
Maintaining adequate hydration is vital for normal functions such as regulating body temperature, ensuring all our organs work normally, and getting rid of body waste, and is especially important when travelling as we tend to be more active.’’
How much is enough?
Dr Cohen says that while pre-hydrating before a flight doesn’t hurt, the most efficient way to complete a sky-high journey in good nick is to drink nourishing liquids during the jaunt.
“While it’s important to ensure adequate hydration before boarding, the natural body process of sweating, breathing and going to the toilet results in significant loss of water so it’s important to drink regularly during the flight,’’ he says.
“The general recommended intake is at least 1.5 to 2 litres daily — increased to 2 to 3 litres over a 10 to 15-hour flight — so aim at drinking a glass of water or juice every hour, alternate with water between every drink containing alcohol or caffeine, and oral rehydration solutions like Gastrolyte or Hydralyte can help.’’
Copy the crew
Flight attendants carry their empty water bottle through airport security, then fill the container once past the X-ray machines.
“Airside’’, Qantas staff add a slice of lemon or drop of apple juice to help the body absorb the nourishment rather than simply passing through the system. Crew sip green tea instead of coffee when seeking a boost, and pack low-salt snacks to eat instead of airline food.
Jetstar flight attendant Larissa Sheppard says that after 12 years of flying she knows to “always start with a big bottle and take small sips during the flight’’.
“Don’t chug your water all at once at it thins your blood and makes you go to the toilet more often. I also take vitamin sachets to put in water because they add a bit of flavour and encourage me to drink more.
“It’s a bit of a myth you shouldn’t drink coffee or tea, as long as you don’t have too much, and cosmetically the crew loves face mist as well as lip balm or lip gloss and lots of moisturiser.’’
While passengers — especially those flying economy — are encouraged to take a personal water bottle to be filled after clearing security, it’s important to remember bag check is completed at the gate in airports like Singapore, Kuala Lumpur and Bangkok so when in doubt leave it empty until on board.
Samantha Lippiatt, co-founder of Health and Fitness Travel, says that while savvy flyers know to skip the booze and avoid salty foods there are steps parched travellers can take to revive after touching down.
“Drink lots of water to help your body expel waste and reduce bloating and, if you’ve landed in a tropical destination, order a fresh coconut which is not only tasty but contains a large dose of nutrients,’’ the healthy-holidays specialist notes.
“Eat water-rich foods such as salad, veggies — lettuce, spinach, cucumber, capsicum, tomato, celery — and in-season fruits because, with salts and natural sugars, the water within is easily drawn across the digestive membrane into the bloodstream to nourish the whole body.
“Even though you might feel tired and groggy, skip tea and coffee, and if you’re on holidays and can’t abstain from alcohol, stick to clear liquids like vodka and gin mixing with soda, and alternate with a glass of water.’’
This story originally appeared in Escape on Sunday, March 18, 2018