Drinking beetroot juice enables competitive-level cyclists to cut down the time it takes to ride a given distance, finds a research.
Beetroot juice is a natural source of nitrate, which is thought to be the active ingredient in affecting athlete's performance.
For the study, nine club-level competitive male cyclists were asked to compete in time trials over 4km and 16.1km.
All the riders were asked to do each time trial twice. Each time they drank half a litre of beetroot juice beforehand.
On one occasion they had normal beetroot juice, on the other occasion - unbeknown to the triallists - the beetroot juice had a key ingredient, nitrate, removed.
The researchers monitored athletes' VO2 levels (showing the amount of oxygen consumed) during exercise to ensure that the cyclists worked at maximum effort on each occasion.
Results showed that when the cyclists drank ordinary beetroot juice they had a higher power output for the same level of effort - suggesting their muscles and cardio-vascular system were being more efficient.
On average, riders were 11 seconds quicker over the 4km distance and 45 seconds faster over the 16.1km distance.
"This is the first time we've studied the effects of beetroot juice, and the high nitrate levels found in it, on simulated competition," said lead author Professor Andrew Jones, from the University of Exeter.
"The findings show an improvement in performance that, at competition level, could make a real difference - particularly in an event like the Tour de France where winning margins can be tight," he added.
The study has been published in the journal Medicine and Science in Sports and Exercise.