Beetroot and Nitric Oxide: A Real but Modest Endurance Edge

Few foods have made the leap from salad bar to performance lab quite like the humble beetroot. Over the past decade, beetroot juice and concentrated nitrate “shots” have become a fixture in the kitbags of cyclists, runners, and triathletes—based on a real and reasonably well-replicated physiological effect.

The active ingredient isn’t anything unique to beets. It’s inorganic nitrate, a compound found in beetroot, leafy greens like spinach and arugula, and other vegetables. Beets just happen to be a convenient, concentrated, palatable delivery vehicle. Understanding how that nitrate becomes a performance aid—and where the effect runs out—is what separates an informed user from someone drinking pink juice on faith.

The Nitrate Pathway

The mechanism runs through a clever biological relay. You consume nitrate; bacteria in your mouth reduce some of it to nitrite; and under the low-oxygen, acidic conditions of hard-working tissue, that nitrite is converted into nitric oxide.

Nitric oxide is a signaling molecule with several relevant jobs: it relaxes and widens blood vessels and appears to improve the efficiency of muscle contraction and mitochondrial function.

The headline finding isn’t that beetroot makes you fitter—it’s that it can make you do the same work using slightly less oxygen.

That improvement in “exercise economy” is the core effect. If your muscles can produce the same power for a lower oxygen cost, you can theoretically sustain an effort longer or go slightly faster at the same perceived effort.

One practical consequence of the oral-bacteria step: strong antibacterial mouthwash can blunt the pathway by killing the bacteria that do the first conversion. It’s a small detail with an outsized effect on whether beetroot works.

What the Evidence Shows

The research base here is more solid than for many supplements, but it comes with real nuance. Randomized trials and meta-analyses suggest dietary nitrate produces a small but consistent improvement in endurance performance and exercise economy in many contexts. The effect is genuine; it is also modest.

Crucially, the benefit isn’t uniform across everyone:

• Most likely to benefit: recreationally trained and moderately fit individuals, especially in efforts where oxygen economy matters.
• Less likely to benefit: elite endurance athletes, whose highly optimized physiology may already produce abundant nitric oxide, leaving less room for improvement.
• Effort type matters: the clearest effects appear in sustained submaximal-to-hard endurance and in some repeated-sprint contexts.

This pattern—bigger effects in less-trained people, diminishing in elites—shows up repeatedly and is worth taking seriously. The “secret weapon of pros” framing is somewhat backwards.

Timing and Dosing

Beetroot has two usable modes: an acute pre-event dose and chronic daily loading, which may build a slightly larger effect.

The relevant variable is the amount of nitrate, not the volume of liquid. Concentrated shots exist precisely because you’d otherwise need to drink an impractical amount of juice to hit the studied doses, which sit in the range of several hundred milligrams of nitrate.

A practical pre-race checklist:

1. Take it a few hours before the effort, not five minutes before.
2. Avoid antibacterial mouthwash and chewing gum around dosing—they can sabotage the pathway.
3. Trial it in training first. Beets can cause GI discomfort in some people, and you don’t want surprises on race day.

Caveats Worth Knowing

A harmless but startling side effect is beeturia—pink or red urine and stool from the pigment. It’s not blood and not dangerous. More relevant is that responses vary considerably between individuals, so a personal trial matters more than the average effect in a study.

There’s also been longstanding nuance in the science around dietary nitrate from vegetables versus nitrates from other sources; the vegetable-derived, whole-food context here is generally regarded as benign and is not the same conversation as processed-meat additives. Still, this isn’t medical advice, and anyone on blood-pressure medication or with relevant conditions should check before loading up, since nitric oxide affects vascular tone.

The Bottom Line

Dietary nitrate from beetroot is one of the better-supported endurance aids, working by improving exercise economy through the nitric oxide pathway. The effect is real but modest, larger in recreational athletes than elites, and easily undermined by something as mundane as mouthwash. Trial it in training, dose it a few hours out, and treat it as a small edge rather than a transformation.