London: Beetroot seems to boost the speed and stamina of runners because of the presence of high levels of performance-enhancing chemicals called nitrates, says a study at the St. Louis University in the US.
Researchers recruited 11 fit and healthy men and women and got them to twice run 5 km on a treadmill -- first, after asking them to consume a portion of baked beetroot just over an hour before the exercise.
Before the second run, they ate an equivalent amount of cranberry relish, chosen because it has a similar calorific content to beetroot but without the same nitrate levels. The result showed that after eating the relish, they averaged 11.9 km per hour, the Journal of the Academy of Nutrition and Dietetics reports.
But after scoffing beetroot, their average speed was up to 12.3 km per hour.
Researchers said runners appear to be able to maintain their speed for longer if they have eaten the vegetable, according to the Daily Mail.
They also reported that "during the last 1.1 miles of the run, speed was five percent faster in the beetroot trial. Consumption of nitrate-rich, whole beetroot improves running performance in healthy adults".
The findings support earlier research, published in 2009, by British scientists which suggested drinking beetroot juice could have a powerful effect on stamina and endurance, as well as lower blood pressure.