Drinking nitrate-rich beetroot juice boosts stamina and could help athletes exercise for up to 16% longer, according to a newly published study.

Researchers gave eight men aged between 19 and 38 500ml per day of organic beetroot juice for six consecutive days before completing a series of tests, involving cycling on an exercise bike. On another occasion, they were given a placebo of blackcurrant cordial for six consecutive days before completing the same cycling tests.

After drinking beetroot juice the group was able to cycle for an average of 11.25 minutes, which is 92 seconds longer than when they were given the placebo. This would translate into an approximate 2% reduction in the time taken to cover a set distance. The group that had consumed the beetroot juice also had lower resting blood pressure.

The research team said it believed the nitrate contained in beetroot juice led to a reduction in oxygen uptake, making exercise less tiring. They were not yet sure of the exact mechanism that caused the nitrate in the beetroot juice to boost stamina. However, they suspected it could be a result of the nitrate turning into nitric oxide in the body, reducing the oxygen cost of exercise.

The research was carried out by the University of Exeter and Peninsula Medical School and published in the Journal of Applied Physiology. The researchers said they hoped to conduct further studies to try to understand in more detail the effects of nitrate-rich foods on exercise physiology.

Corresponding author of the study, Professor Andy Jones of the University of Exeter's School of Sport and Health Sciences, said: "Our study is the first to show that nitrate-rich food can increase exercise endurance. We were amazed by the effects of beetroot juice on oxygen uptake because these effects cannot be achieved by any other known means, including training. I am sure professional and amateur athletes will be interested in the results of this research. I am also keen to explore the relevance of the findings to those people who suffer from poor fitness and may be able to use dietary supplements to help them go about their daily lives."

References
S.J. Bailey, et al. "Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans," Journal of Applied Physiology. Published online ahead of print, doi:10.1152/japplphysiol.00722.2009