If you’ve been around any running group or race expo in the last couple years, you’ve probably heard about the trend of using beet juice to enhance running performance. But is there anything to back this claim?
The answer is yes…but as research at the latest ACSM Annual Meeting noted, it may depend on your biological sex, age, training status, and your morning mouthwash routine! In particular, pre-menopausal female athletes may not get the same performance boost as men or post-menopausal female athletes. And folks who use mouthwash before drinking beet juice also don’t get the same benefit.
Let’s back up a second though – how does beet juice work to improve performance? And why do these factors like age or mouthwash matter?
Disclaimer: This post was written by Chrissy Carroll, MPH, RD, RRCA Running Coach, USAT Level I Triathlon Coach. It is for informational purposes only and should not be construed as individual nutrition advice. Consult a doctor or dietitian prior to trying any new supplement routine.
Beet Juice and Performance
Beet juice was hypothesized to be a performance enhancer due to due to its high concentration of dietary nitrates. When dietary nitrates are consumed, they are first converted to nitrite (mainly through the natural bacteria in our mouth). That nitrite is later converted to nitric oxide in other parts of the body.
Since nitric oxide is a well-known vasodilator, the theory is that it would help improve blood and oxygen flow to working muscles, possibly helping improve performance.
There have been numerous studies done on beet juice supplementation and performance. A 2017 systematic review concluded:
“The available results suggest that supplementation with beetroot juice can improve cardiorespiratory endurance in athletes by increasing efficiency, which improves performance at various distances, increases time to exhaustion at submaximal intensities, and may improve the cardiorespiratory performance at anaerobic threshold intensities and maximum oxygen uptake (VO2max).”
Pretty cool, right?
These are relatively moderate improvements; generally about a 1-5% improvement depending on what is being examined (i.e. time trial performance vs. other tests).
And note – if you’re reading this wondering “why not just eat beets?” – the optimal dose of dietary nitrates is around half a liter of traditional beet root juice or 3 to 4 cooked beets. That’s a lot of volume to eat before a run, which is why the concentrated beet juice shots are an easier alternative. Also, the amount of dietary nitrates in beets varies based on the cultivar and region grown, so you don’t always know the amount of nitrates you’re getting from those.
However, there are several factors that influence whether beet juice may improve your performance…
Age and Biological Sex
Data presented at the ACSM conference showcased several studies (both published and unpublished data) that highlighted how age and biological sex may play a role in the efficacy of beet juice. Specifically, there may not be a performance boost for pre-menopausal females.
Research from 2023 compared beet juice supplementation in young adults, and compared the impacts on males vs. females. While beet juice improved exercise economy by 5% and extended time to exhaustion by 15% in males, it did not have any impact in females (all likely pre-menopausal based on ages of the participants).
Similarly, unpublished data presented by Samantha Rowland at the ACSM conference looked at pre-menopausal females that use oral contraceptives. They found no effect of dietary nitrates on endurance performance, regardless of pill phase.
Another 2023 study found that dietary nitrate supplementation did not affect exercise economy, and actually worsened time to exhaustion in a severe exercise intensity test. This was true regardless of the phase of the menstrual cycle.
These exact mechanisms behind these different results between males and pre-menopausal females remains unknown. Some potential reasons could be females having a higher baseline plasma nitrate level, or the different proportions of muscle fiber types. It could also be due to the role of estrogen, which plays a role in endogenous nitric oxide production. Again, it’s unclear.
However, post-menopausal females may still retain a benefit from beet juice supplementation. We need more research, though.
There was only one study I could currently locate that looked at a measure of endurance performance in post-menopausal women consuming dietary nitrates. This study looked at 6-minute walk test performance, and found better results with dietary nitrate supplementation compared to the placebo group. (Woohoo!)
Outside of performance, there may be some health benefits to consuming beet juice for post-menopausal women. The session at the ACSM conference mentioned research from 2023, which found dietary nitrates combined with moderate and high intensity exercise improved flow mediated dilation, a measure of vascular health, in post-menopausal women.
Similarly, in post-menopausal women with hypertension consuming dietary nitrates, there was enhanced cardiovascular behavior in response to aerobic exercise. Those consuming beet juice saw a drop in systolic blood pressure in the post-exercise time frame and improved flow mediated dilation. So even if there is not a performance benefit, this could be a reason to incorporate beet juice.
Training status
Beet juice may be more likely to impact low to moderately trained athletes, compared to highly trained athletes. (This contrasts with some of the earlier theories on nitrates.)
Several studies have looked at elite or highly competitive athletes in sports like field hockey, rugby, tennis, taekwondo, and swimming, and found no improvement in performance with beet juice.
With regards to running specifically, a study found that beet juice supplementation did not improve 1500 meter performance in elite athletes, and another study found that it did not improve 10K performance in well-trained runners at altitude. Similarly, a 2021 study on elite race walkers did not find a beneficial effect of beet juice on exercise economy.
However, studies on lesser trained athletes generally show better results. For example, one study looked at “recreationally active males” , and found that beet juice supplementation did improve performance in an intermittent running test. Another study on recreational runners found that beet juice supplementation improved VO2 max and peak velocity.
There is still inter-individual variability, though, regardless of training status. For example, one study found that 10 of 14 recreational runners experienced improvements in 10K times with beet juice supplementation – but the other 4 did not.
Overall more research still needs to be done!
Mouthwash use
This is perhaps the most well-established factor that can affect the results of beet juice supplementation. As a reminder, when you drink beet juice, the dietary nitrates are first converted to nitrite by the bacteria that live in our mouth. This step needs to happen so that those nitrites can later be converted to nitric oxide.
If you use mouthwash, you kill some of the bacteria in your mouth that are needed for this step. Research has shown that using mouthwash reduces the level of plasma nitrites later found in the blood. This may eliminate the likelihood of any potential performance benefit.
Practical Applications
If you’re a runner and you want to try adding beet juice to your routine, here are a few practical tips:
- Try beet juice shots (or similar product) around 2-3 hours before your long training run or event.
- Look for products that contain at least 350-500 mg (6-16 mmol) of dietary nitrates. You may need to take more than one serving depending on the product – there is quite a bit of variability among products. Work with a dietitian to find the right option and amount for you!
- Practice during training so you know how it affects your gastrointestinal system – you don’t want to try anything new on race day.
- Don’t use any mouthwash before taking the beet juice shot.
- Some studies are showing a benefit of chronic supplementation, meaning taking supplements for several days or weeks leading up to an event. This could be something to experiment with.
- Use caution if you suffer from any low blood pressure issues, as this may further decrease blood pressure. Discuss with your doctor first.
Also, just be aware that beet juice or beets can cause temporary tooth discoloration and reddish/purplish poop! (The things we do as athletes…)
The Bottom Line
It is likely that there is quite a bit of variability in the benefits of beet juice based on your age, biological sex, training status, mouthwash routine, and even your unique microbiome and genetics. Male and post-menopausal female runners appear to retain the best chance at seeing a performance boost, specifically among those who are recreational rather than elite athletes. And don’t forget to skip the mouthwash before chugging your beet juice!
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