Beetroot and VO2max are often mentioned in the same breath, with nitrate being the molecule that makes the link. But much of what is claimed about this does not hold up if you read the science honestly. What research suggests about nitrate is more nuanced than many popular claims. I explain what is known, for whom small effects have been measured, and why carbs remain an entirely different story. For the broader basis regarding fuel during exercise, I refer you to the complete guide to energy bars and cycling.

What is nitrate and why does it interest endurance sports researchers?

Nitrate is a compound found naturally in vegetables, with beetroot being the richest source. A 500 ml serving of beet juice contains roughly 400 to 500 mg of nitrate, approximately 6 to 8 mmol. In your body, nitrate is converted by bacteria in your mouth into nitrite, and then into nitric oxide. Sports scientists are researching this substance as potentially relevant to exercise physiology.

Research is investigating whether nitric oxide can affect blood vessels and what role that plays in oxygen consumption. Studies also suggest that the body may be able to use oxygen more efficiently: the same work might cost less oxygen. These mechanisms are the subject of much research. The meta-analysis by Pawlak-Chaouch (2016) indicates that in some studies, oxygen consumption during submaximal exercise—that is, below the maximum—changed in certain zones. However, these results vary significantly between studies.

Note the nuance: studies focus on economy, not your maximum capacity. Your VO2max, the maximum volume of oxygen you can take up, does not change or barely changes due to nitrate according to research. The research theme is whether nitrate might make you more economical on the way to that ceiling, not whether it raises the ceiling itself.

Does beetroot increase your VO2max? What research suggests

Short answer: very likely not. VO2max is the maximum amount of oxygen you can take up and use per minute, expressed in milliliters per kilo per minute. Elite cyclists reach 70 to 85 ml/kg/min; trail runners and triathletes are in the same regions. Research does not suggest that nitrate pushes this number up. What research may indicate are two possible directions: effects on the oxygen cost of exercise below your maximum, and possible effects on exercise duration.

The most recent umbrella review, by Poon (2025), aggregates 20 meta-analyses involving a total of 180 studies and nearly 2,700 participants. The conclusion is nuanced: in some studies, a small effect was measured on exercise duration, most clearly with higher doses of at least 6 mmol per day and with intake over multiple days. However, there was no effect on many other measured outcomes, and the methodological quality of many underlying studies was low. Nitrate is therefore, in the case of studies that found effects, a small potential nudge, not a switch.

Another honest point that is often omitted: as research suggests, the better trained you are, the smaller the potential effects. The meta-analysis by d'Unienville (2021) indicates that well-trained endurance athletes with a VO2max above 65 ml/kg/min do not derive a demonstrable benefit from it. For recreational and sub-elite athletes, research suggests the chance of small effects is greatest.

When does research suggest nitrate is potentially most relevant?

Timing and dosage determine a lot in research results. Most studies use 6 to 8 mmol of nitrate, about 400 to 500 mg, taken 2 to 3 hours before exercise. Research suggests that nitrite levels then peak in the blood. Research into loading nitrate for several days, over 3 to 6 days, suggests similar or slightly stronger potential effects than a single dose right before the start.

Your mouth is a factor that receives attention in studies. The bacteria on your tongue convert nitrate to nitrite in studies. Antibacterial mouthwash or toothpaste just before ingestion can, according to studies, kill those bacteria and block the conversion. Anyone using a strong mouthwash on the morning of a competition could, according to researchers, reduce a portion of the potential effect.

And so it holds: research suggests that potential effects are greatest in those who have room for improvement. For recreational and sub-elite athletes in moderate to heavy exercise zones, research suggests the most potential gain. For well-trained athletes, the researched margin is small to non-existent. Use it purposefully or don't use it at all.

What does this mean for cycling and trail running?

In cycling, climbing segments lasting from a few minutes to a quarter of an hour are the scenarios where research looks at oxygen economy. Research suggests that a potentially lower oxygen consumption at the same power output on a climb could yield a small time difference. Important: that effect is most measured in studies among the broad middle tier, less so among top performers who already ride efficiently according to research.

In trail running, the relevant blocks are found in steep climbs that you take at high intensity. The terrain constantly changes between hard and soft, and it is precisely during the peaks that efficiency is tested according to research. Here, too, research suggests that any potential gain is realistically small and depends on your training level. For triathletes, the same logic applies on the bike and in the early running phase.

Nitrate is not a miracle cure. It is, in research, a subject of study with a narrow window: high intensity, short to medium duration, and especially interesting if you do not yet belong to the best-trained category. Anyone looking for another legal performance aid with much firmer evidence is better off reading about caffeine and the science behind every watt.

Nitrate and carbs: two separate areas of research

Nitrate and carbohydrates work along completely different routes in research. Research suggests that nitrate, if effective, may influence how your body uses oxygen. Carbohydrates are the fuel itself: glucose and fructose are burned to provide energy for your muscles. One does not replace the other.

For exercise longer than an hour, the recommendation is 60 to 90 grams of carbs per hour, regardless of any nitrate intake. You absorb those carbs via two separate transport channels in your gut, one for glucose and one for fructose. By offering them in a 2:1 ratio, you open both channels simultaneously and extract up to 90 grams per hour from your gut instead of around 60 grams with glucose alone. This mechanism is independent of nitrate. You can read more about the trade-off between solid and liquid fuel in energy bar versus energy gel: when to use what.

In practice, you build your fueling like this: sports drink with 6 to 8% carbs as the main source, good for 30 to 60 grams per hour, supplemented with 1 to 2 fruit performance bars per hour of 20 grams of carbs each. Together, you are comfortably in the 60 to 90 gram zone. Nitrate does not solve the fuel problem. Carbs do. The two are mechanistically distinct: research looks at nitrate as a potential modulator of oxygen consumption, while carbs are a direct energy source.

Is there nitrate in the Eagle fruit performance bar?

No. My fruit performance bar contains no added nitrate or beetroot juice. I build the bar around fruit pulp and a 2:1 glucose/fructose ratio, with a clean label and no artificials. Nitrate is something you would approach separately via nutrition such as beetroot. The bar is there for during the ride, the run, or the race.

What the bar and nitrate research do share is the same philosophy: clean, functional input without unnecessary additives and without overclaims. No artificials. Transparent operation via known mechanisms. That is also why I am honest above about the limits of what research suggests about nitrate: I am not selling you a promise that exceeds what science supports. I explain the difference between a regular sugary snack in fruit energy bar versus candy, and why many riders are swapping out the gel is something you can read in this blog about the clean-label bar.

Beetroot and endurance sports, summarized

Research suggests that nitrate can have small potential effects on oxygen consumption and exercise duration. When effects have been measured, they were greatest in recreational and sub-elite athletes with doses of 6 to 8 mmol, 2 to 3 hours in advance or loaded over several days. In well-trained athletes, research suggests small to no effects. Research does not suggest that nitrate increases your VO2max.

See it as a research area with a specific window, not a replacement for training, fuel, or recovery. Research investigates how nitrate may potentially influence oxygen consumption. Carbs provide the direct fuel. Anyone who understands both mechanisms can train sharply and fuel fully.

Choose your fuel