What Science Says About Beetroot Juice and Endurance

Beetroot juice can modestly improve endurance performance, mainly by lowering the oxygen cost of submaximal exercise, but the size of the benefit depends heavily on who you are and how hard you are going. A 2025 meta-analysis by Tian and colleagues, published in Nutrients, found beetroot juice significantly improved muscle strength measures, though with a negligible standardized effect size of 0.08, alongside more meaningful aerobic endurance benefits, per the study's PubMed record.

This article publishes information, not medical or dietary advice. Readers on medication or managing health conditions should speak with a qualified professional before supplementing.

What is dietary nitrate, and how does it work?

Nitrate is a compound found concentrated in beetroot, leafy greens and other vegetables. After you consume it, bacteria in the mouth convert part of it to nitrite, which the body then converts to nitric oxide, a molecule that widens blood vessels and helps regulate oxygen use in muscle. That pathway, described in a widely cited 2017 review by Dominguez and colleagues in the journal Nutrients, is the reason researchers became interested in beets in the first place.

The practical consequence for athletes is a reduction in the oxygen cost of exercise at a given workload, which effectively means submaximal work feels marginally cheaper. Time-to-exhaustion tests, where riders pedal at a fixed intensity until they cannot continue, respond most clearly. Fixed-distance time trials respond less, because race-pace effort sits closer to the body's ceiling where nitric oxide's role changes.

What do the meta-analyses actually show?

The evidence base is unusually deep for a food-based aid. A 2021 systematic review and meta-analysis by Gao and co-authors, covering dozens of trials, concluded dietary nitrate supplementation improves endurance sport performance, with the strongest effects in recreational and moderately trained participants. Tian's 2025 meta-analysis added longer-term detail: aerobic measures improved, while the strength effect, though statistically significant, was negligible in size.

Not every trial agrees. A 2025 systematic review by Poon and colleagues in Sports Medicine catalogued mixed results, including no significant improvement in peak power during high-intensity interval efforts. The honest summary: nitrate reliably moves physiological markers, sometimes improves time-to-exhaustion, and often fails to move high-intensity performance in already well-trained athletes.

Why do elite athletes get less out of it?

Training itself raises nitric oxide availability. Highly trained athletes already sit near the ceiling of what the pathway can deliver, so the supplement has less room to add. The 2021 meta-analysis evidence points the same way: recreational athletes show the clearest gains, elites the smallest.

Fitness also shortens the timeline. In untrained subjects, benefits can persist after days of supplementation as muscle stores adapt. In trained cyclists and runners, acute timing matters more, which is why protocols in the literature cluster around a single dose roughly two to three hours before exercise.

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How have researchers dosed it?

The trials generally use concentrated beetroot juice shots delivering roughly 6 to 8 millimoles of nitrate, taken about two to three hours before exercise, a protocol summarized in the 2017 Dominguez review. Ordinary beetroot contains the same compound, but the volume needed to match a concentrated shot is large enough that most studies used the standardized product to keep dosing comparable.

One widely overlooked detail from the same literature: antibacterial mouthwash reduces the effect, because the oral bacteria that start the nitrate-to-nitrite conversion live on the tongue. Athletes who rinse with strong antiseptic mouthwash daily may blunt the pathway the juice is meant to feed.

Timing around training blocks also deserves thought. Some studies loaded nitrate for several days before a test, which raises muscle nitrite stores, while others used a single pre-event shot. Both approaches appear in the literature, but a weekend racer who only doses on race day is following the acute arm of the research, not the loading arm, and should calibrate expectations accordingly.

Is beetroot juice legal in sport?

Yes. Dietary nitrate from vegetables is not on the World Anti-Doping Agency's prohibited list, and it has been studied openly in Olympic-sport research for well over a decade. That legal status is a large part of its appeal compared with more aggressive compounds, and it is also why the quality of the evidence matters: this is one of the few ergogenic aids where the base of randomized trials is genuinely large.

It is not risk-free in every context, though. Large repeated doses can color urine red, which is harmless but can be mistaken for blood, and concentrated products add potassium and sugars that belong in a athlete's overall intake calculations.

Honest expectations matter here. In the trials that found benefits, the improvements in time-trial power were typically measured in low single-digit percentages, the kind of margin that decides a podium but invisible on an easy training day. Anyone expecting the juice to rescue a poorly planned block will be disappointed; anyone curious whether a legal, well-studied marginal gain is available at their fitness level is asking the right question.

Should you try it?

The reasonable reading of the evidence: if you are a recreational or moderately trained endurance athlete targeting events from roughly 4 to 40 minutes, the literature supports a trial of a concentrated nitrate dose two to three hours before hard sessions and races, tested in training first. If you are elite, expect little. If your event is decided by sprint power, the current evidence says the juice is not doing much for you.

As with every supplement decision, the boring questions decide more than the product: is your training consistent, is your sleep adequate, is your everyday diet rich in vegetables anyway? Nitrate is a refinement on top of fundamentals, not a substitute for them.