A University of Exeter (U-E) led-study shows for the first time how nitrate in beetroot juice leads to a reduction in oxygen uptake, therefore making exercise less tiring.



Study co-author Andy Jones, professor at the U-E School of Sport and Health Sciences, said: "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.

The research team believes that the findings could be of great interest to endurance athletes. They could also be relevant to elderly people or those with cardiovascular, respiratory or metabolic diseases.

The research team conducted their study with eight men aged between 19 and 38. They were given 500 ml of organic beetroot juice daily 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 black currant 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 two percent 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 researchers are not yet sure of the exact mechanism that causes the nitrate in the beetroot juice to boost stamina. However, they suspect it could be a result of the nitrate turning into nitric oxide in the body, reducing the oxygen cost of exercise.

The research was published in the Journal of Applied Physiology.

Lead by Professor Amrita Ahluwalia of the William Harvey Research Institute at Barts and The London School of Medicine, and Professor Ben Benjamin of Peninsula Medical School, the research reveals that it is the ingestion of dietary nitrate contained within beetroot juice – and similarly in green, leafy vegetables – which results ultimately in decreased blood pressure. Previously the protective effects of vegetable-rich diets had been attributed to their antioxidant vitamin content.

Professor Ahluwalia and her team found that in healthy volunteers blood pressure was reduced within just 1 hour of ingesting beetroot juice, with a peak drop occurring 3-4 hours after ingestion. Some degree of reduction continued to be observed until up to 24 hours after ingestion. Researchers showed that the decrease in blood pressure was due to the chemical formation of nitrite from the dietary nitrate in the juice. The nitrate in the juice is converted in saliva, by bacteria on the tongue, into nitrite. This nitrite-containing saliva is swallowed, and in the acidic environment of the stomach is either converted into nitric oxide or re-enters the circulation as nitrite. The peak time of reduction in blood pressure correlated with the appearance and peak levels of nitrite in the circulation, an effect that was absent in a second group of volunteers who refrained from swallowing their saliva during, and for 3 hours following, beetroot ingestion.

More than 25 per cent of the worlds adult population are hypertensive, and it has been estimated that this figure will increase to 29 per cent by 2025. In addition, hypertension causes