London:
Next time you go trekking in the mountains, carry beet juice with you, as researchers have found for the first time that drinking beet juice can help the body cope with low levels of oxygen at high altitudes.
Mountain climbers have always struggled with a basic problem - altitude sickness, caused by lower air pressures which affect the ability of our bodies to take up oxygen.
The best way to minimise the risk of developing acute mountain sickness (AMS) is acclimatisation, or simply spending enough time up high to allow the body to make adjustments to lower oxygen levels.
A team of researchers decided to see how nitrate-rich beet juice might affect acclimatisation on a 39-day expedition to Kathmandu and at 3,700 metres in the Rolwaling Valley, Nepal.
Normal blood vessel function depends on the body's ability to naturally produce a compound nitric oxide (NO).
Production of adequate amounts of NO at high altitudes is a challenge since natural NO production requires oxygen.
But the body has a "back-up system" for NO production at altitude, and it is here that beet juice can help.
The secret ingredient in beet juice is high levels of nitrate, which the body can then convert to NO.
Previous research has shown that blood vessels tend to contract at high altitude.
For the study, researchers measured blood vessel function with a standard test of arterial endothelial function, a flow-mediated dilatation test (FMD) that uses ultrasound.
The researchers, from the Norwegian University of Science and Technology (NTNU) and the Mid-Sweden University, showed that consumption of organic nitrate-rich beet juice restored reduced blood vessel function at high altitude.
Both men and women were studied with ultrasound to check their blood vessel function, before and during the high altitude expedition. As expected, high altitude made blood vessels contract.
To test if beet juice could make the blood vessels relax again, the test subjects were studied after drinking two types of beet juice with a 24-hour break between tests.
One of the juices contained high amounts of nitrate while the other type had no nitrate in it (placebo).
Neither the study participants nor the researchers knew what type of beet juice each person drank before blood vessel function was measured, and the juices (nitrate-rich versus placebo) were given in a random order.
The study showed that beet juice with high amounts of nitrate made the blood vessels relax and return to normal function, while the placebo did not have any effect.
"Next time you plan a trip at high altitude, maybe it is worth carrying a bottle of beet juice in your backpack," said the study's corresponding author, Svein Erik Gaustad, from NTNU.
The study was published in the journal Nitric Oxide: Biology and Chemistry.