Evidence that beetroot juice can improve athletic performance has long been inconsistent. While some studies reported benefits, others found little or no effect. Now, a new study, combining results from 33 studies, provides the clearest evidence yet that it can enhance exercise performance.

The meta-analysis included data from more than 500 professional and recreational athletes. The results showed that consuming beetroot juice before exercise made a measurable difference to how well they were able to tolerate an intense session.

The greatest benefits were seen when athletes consumed either 70–140ml of concentrated beetroot juice or 250–500ml of standard beetroot juice around two hours before exercise. They showed small-to-moderate improvements in explosive strength, sprint speed and oxygen use.

The secret behind this performance boost is a compound called dietary nitrate, which occurs naturally in foods such as beetroot and leafy green vegetables. When these foods are consumed, the body converts dietary nitrate into an important molecule known as nitric oxide.

While nitric oxide is used in medicine to treat patients for respiratory failure, it also has a critical role in the healthy functioning of blood vessels. When blood vessels are exposed to nitric oxide, they relax........

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