Beetroot juice and endurance: what the science actually says

Beetroot has a bigger reputation than almost any other sports food. You have probably seen runners knocking back a little bottle of dark red juice before a race, or read that it makes you faster for free. The truth is more interesting, and more modest. Dietary nitrate, the active ingredient in beetroot and in a lot of leafy greens, really can help endurance, but the effect is small, it varies from person to person, and it matters more for some efforts and some runners than others. Here is what the research actually shows, and how to try it without wasting your money or ruining your favourite shorts.

How does beetroot actually work?

Beetroot is rich in dietary nitrate. When you eat or drink it, friendly bacteria on your tongue convert some of that nitrate into nitrite. Once it is swallowed and reaches the bloodstream, your body can turn nitrite into nitric oxide, a molecule that helps blood vessels relax and widen.

For a runner, the interesting part is what that may do during exercise. Wider vessels can mean better blood flow to working muscle, and studies suggest nitric oxide can make muscle contraction slightly more efficient, so you use a little less oxygen for the same pace. Scientists call this exercise economy. If it costs you marginally less energy to hold a given effort, you may be able to hold it for longer, or push a touch harder before you fade.

One quirky detail follows from that tongue-bacteria step. Strong antibacterial mouthwash can wipe out the very bacteria that start the conversion, which research has shown blunts the rise in nitrite. If you are going to try beetroot, it is sensible to skip the heavy-duty mouthwash around the same time.

How big is the effect, really?

This is where honesty matters. Reviews that pool many studies together tend to find a small but genuine improvement in endurance performance and in oxygen uptake from beetroot or nitrate supplements, rather than a dramatic one. On average we are talking about a marginal gain, the kind that might matter in a race but that you would struggle to feel on an easy run.

The effect is also not the same for everyone. It tends to be larger in recreationally active people and smaller, or less consistent, in well-trained and elite competitors. The leading explanation is that highly trained bodies are already very good at using nitric oxide, so there is less room for a supplement to help. Results also vary with the dose, how long you take it for, and the type of effort.

Broadly, nitrate looks more reliable for shorter, high-intensity efforts and for repeated hard bursts than for long, steady endurance. So a parkrun, a hard interval session or the closing surge of a 10k may be a better bet than a slow, long marathon plod. None of this is guaranteed, and plenty of individual studies show no clear benefit at all.

Is it worth trying for everyday runners?

For most everyday runners, beetroot is a reasonable thing to experiment with, as long as you keep your expectations sensible. It is cheap enough, it is food rather than a mystery powder, and the potential downside is mostly a stained sink. If you are relatively new to structured training, or you race shorter, sharper distances, you are in the group most likely to notice something.

Just keep it in proportion. A nitrate boost is a marginal gain that sits on top of the things that actually build endurance, which are consistent training, sleep, sensible fuelling and a plan you can stick to. If your week is not yet consistent, that is where the real minutes are hiding, not in a bottle of juice. This is the gap a personalised plan is meant to close, and it is why members at Edge treat running, strength and HIIT as one joined-up programme rather than chasing quick fixes.

How would you actually use it?

Most of the research uses a nitrate dose of roughly 6 to 8 mmol, which is around 400 to 500 mg of nitrate. In practice that is about one to two concentrated beetroot shots, the small bottles sold for exactly this purpose. Concentrated shots are popular because the dose is measured and consistent, whereas ordinary beetroot juice varies a lot in how much nitrate it contains, so it is harder to know what you are getting.

• Timing: take it around two to three hours before your session or race, because blood nitrite tends to peak in that window.
• Loading: some people take a dose daily for a few days beforehand rather than relying on a single hit on the day. Both approaches appear in the research.
• Practise first: try it in training before you ever use it on race day, so you know how your stomach reacts.
• Mouthwash: give strong antibacterial mouthwash a miss around the time you take it, for the reason above.

What are the side effects, and what is the loo warning?

The famous one is harmless but startling the first time. Beetroot can turn your urine pink or red, and sometimes your stool too. This is called beeturia, it is not blood, and it passes on its own. The main practical issue is that beetroot stains almost everything it touches, so be careful with light kit, worktops and the bathroom.

Some people also get a bit of stomach upset from a large dose of juice, which is another reason to test it in training rather than on the start line. And a genuine caution: because nitrate can lower blood pressure, and because of how the body clears it, anyone taking blood-pressure medication, or living with kidney problems, should check with their GP before adding regular beetroot shots. If in doubt, ask first.

Can you just eat nitrate-rich food instead?

Yes, and for general health it is a lovely habit. Beetroot is not the only source of dietary nitrate. Leafy greens are rich in it too, including spinach, rocket and lettuce, along with celery. Building more of these into your normal meals is a sensible, whole-food way to keep your nitrate intake up without relying on shots.

The catch is precision. The nitrate content of vegetables varies with the soil, the season and how they are stored and cooked, so it is hard to hit a specific performance dose from food alone. Think of everyday greens as the steady baseline for health, and a measured shot as the tool if you want to test a targeted boost before a specific effort. Either way, beetroot is a nice-to-have, not a shortcut past the training itself.

This article is general guidance, not medical advice. If you are new to exercise, returning from injury, pregnant, or managing a health condition, speak to your GP before starting, and see a physio for any niggle that does not settle.