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My friend Lizzie, a very athletic doctor, recently showed me some concentrated beetroot shots she was planning to take before an upcoming marathon. I never run anywhere, but she let me try one anyway. I could only manage slow sips of the intensely beetroot-tasting purple liquid, but she assured me it has a raft of benefits for athletes and non-athletes alike. I decided to look into it.

Most beetroot research, I discovered, has been led by , an exercise physiologist at the University of Exeter, UK. His team’s interest in the humble root vegetable arose because it is a natural source of nitrate. In the body, nitrate is converted to nitric oxide, an important signalling molecule that causes blood vessels to widen. This widening reduces blood pressure and .

In their first beetroot , published in 2009, Jones and his colleagues asked eight recreational athletes to cycle hard for as long as possible. They lasted about a minute-and-a-half longer, on average, when they had consumed beetroot juice daily for six days beforehand, compared with when they had blackcurrant juice.

Since then, Jones’s team and others have shown that beetroot juice gives an edge in a range of athletic pursuits, including , and . Beetroot shots have been credited for assisting , and in 2016. The International Olympic Committee lists nitrate (from beetroot or other sources) as with “good to strong evidence of achieving benefits to performance” (the others being caffeine, creatine, sodium bicarbonate and beta-alanine).

But what about for those of us who are firmly in the non-athlete category? I don’t think any amount of beetroot juice could turn me into a marathon runner, but it might make exercising a little bit easier and motivate me to do more. A study by researchers at the University of Alabama at Birmingham found that adults with obesity in a cycling test after having a beetroot shot, hinting that the supplement may “assist easing the burden of exercise and perhaps improve participation in and adherence to exercise”.

I have also read plenty of anecdotes of people on social media saying that beetroot juice makes them feel like they have more energy, and that it is as effective as coffee for beating fatigue. However, this has not been investigated in formal studies, so it may be a placebo effect.

One thing that seems clear is that daily beetroot juice can slightly lower blood pressure in people with hypertension, by around . This isn’t as effective as anti-hypertensive medication, which usually lowers systolic blood pressure by around , but it may be a useful add-on. A study by researchers at King’s College London published last month found that chewing sugary gum after drinking beetroot juice , because it enhances the activity of bacterial enzymes in the mouth that kickstart the chemical reactions that turn nitrate into nitric oxide.

On the other hand, people with low blood pressure are advised to be careful with beetroot juice because they could feel dizzy or lightheaded if their blood pressure drops further. Beetroot juice is also moderately high in natural sugars, so large quantities may not be suitable for those with diabetes.

The late TV doctor Michael Mosley even referred to beetroot as “vegetable Viagra” because he believed its effect on increasing blood flow could bolster erections. “The mechanism is exactly the same as in Viagra,” he . “What Viagra does is lead to the release of nitric oxide and the expansion of blood vessels, but mainly around your genitalia.” Indeed, a supplement containing beetroot extract “increased the duration and intensity of nighttime erections” in a involving 10 men who wore a smart ring around their penis to monitor its firmness while they slept (although the study was sponsored by the supplement manufacturer, which may have biased the results).

It seems the ancient Romans were already on to this, as they used beetroot as an aphrodisiac and incorporated the vegetable in carnal scenes painted . A recently uncovered in Pompeii depicted a plate of food next to a goblet of what was interpreted to be red wine, but perhaps it was actually beetroot juice?

One thing to know if you start imbibing large amounts of beetroot juice is that its red-purple pigment can turn your urine and faeces the same colour. Don’t freak out and think you’re bleeding out.

If you don’t like beetroot, you can also get nitrate from like spinach, rocket (also called arugula), lettuce, celery, tomatoes, bananas and oranges. I personally don’t think I could stomach daily beetroot juice, but I do like the vegetable whole, so I plan to eat more salads with roast beetroot and burgers with sliced beetroot in the hope that they might slightly lift my energy levels. My friend Lizzie always gives me good health recommendations, and in this case, it seems she hasn’t missed a beet.