Drinking beetroot juice boosts stamina¹ and could help people exercise for up to 16% longer, a UK study suggests.

一项英国调查显示，喝甜菜根汁液可以激发活力并使人们体力增强16%之多。

Nitrates seem to be the key ingredient in beetroot

A University of Exeter team found nitrate（硝酸盐） contained in the vegetable leads to a reduction in oxygen uptake - making exercise less tiring.

The small Journal of Applied² Physiology³ study suggests the effect is greater than that which can be achieved by regular training.

Beetroot juice has previously⁴ been shown to reduce blood pressure.

The researchers believe their findings could help people with cardiovascular（心脏血管的）, respiratory（呼吸的） or metabolic⁵ diseases（代谢病） - and endurance（耐性） athletes.

They focused on eight men aged⁶ 19-38, who were given 500ml per day of organic beetroot juice for six consecutive⁷ days（连续作业日，连续营业日） before completing a series of tests, involving cycling on an exercise bike.

On another occasion, they were given a placebo⁸（安慰剂） of blackcurrant（黑醋栗） cordial（兴奋剂，补品） 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 - 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.

Mechanism⁹ unclear

The researchers are not yet sure of the exact mechanism that causes the nitrate（硝酸盐） in the beetroot juice to boost stamina.

However, they suspect it could be a result of the nitrate turning into nitric oxide¹⁰（氧化一氮） in the body, reducing how much oxygen is burned up by exercise.

Study researcher Professor Andy Jones - an adviser¹¹ to top UK athlete Paula Radcliffe - 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.

"I am sure professional and amateur（业余的） athletes will be interested in the results of this research.

"I am also keen to explore the relevance¹² 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."

Professor John Brewer¹³, an expert on sports science at the University of Bedfordshire, said: "These findings are potentially exciting for many people involved in sport and, but will almost certainly require further more extensive studies before the exact benefits and mechanisms¹⁴ are understood.

"We must also remember that exercise and training and a sensible diet will always remain as the essential ingredients（作料，材料） for a balanced and healthy lifestyle."

Dr Simon Marshall, of the University of San Diego, has carried out work on exercise and health.

He said much more work was needed involving many more subjects to draw firm conclusions.

"Certainly, a diet high in nitrate-rich fruits and vegetables is good for your heart health and this study provides further evidence of this."