Beetroot and Citrulline for Workouts: Do Nitric Oxide Supplements Improve Performance?

Some pre-workouts try to overwhelm you with stimulants.

Others take a different approach:

increase nitric oxide.

The idea sounds appealing.

More nitric oxide may relax blood vessels.

Relaxed blood vessels may increase blood flow.

More blood flow may mean improved delivery of oxygen and nutrients to working muscles.

And that could potentially mean:

better endurance,

greater muscular efficiency,

more repetitions,

higher power,

and a stronger gym “pump.”

Two of the most popular ingredients used for this purpose are:

beetroot

and

L-citrulline.

They both influence nitric-oxide biology—but through different pathways.

And that difference matters. Beetroot and Citrulline

Dietary nitrate from beetroot has relatively strong evidence for selected endurance, muscular-endurance, and power outcomes, particularly when enough nitrate is consumed. Citrulline can increase circulating arginine and nitric-oxide-related markers, but exercise-performance findings are considerably more mixed. Combining the two is scientifically plausible, but current evidence does not prove that beetroot + citrulline automatically produces a stronger workout effect than either ingredient alone.

That becomes particularly relevant when evaluating products such as Pre Lab Pro, which combines:

1,500 mg standardized beetroot

with

2,200 mg Setria® Performance Blend containing L-citrulline + glutathione.

The ingredients make biological sense.

But the doses and research context deserve a closer look.

Important: This article is educational and is not medical advice. Nitric-oxide-support supplements can affect blood pressure and circulation, and people taking medications or managing cardiovascular conditions should seek appropriate professional advice before using them.

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Beetroot vs Citrulline: What’s the Difference?

Both ingredients can ultimately influence nitric oxide.

But they get there through different pathways.

Beetroot

Beetroot contains dietary nitrate.

The body converts:

nitrate → nitrite → nitric oxide

through what is known as the nitrate–nitrite–nitric oxide pathway.

This pathway is particularly interesting during exercise because conversion to nitric oxide can become more active under lower-oxygen and acidic conditions—exactly the type of environment that develops in hard-working muscle.

Citrulline

L-citrulline works through another route.

The body converts citrulline into:

L-arginine

and arginine can then be used by nitric-oxide synthase enzymes to create:

nitric oxide.

So in simplified terms:

Beetroot supplies nitrate.

Citrulline increases arginine availability.

Both may raise nitric-oxide signaling, but they are not interchangeable. Beetroot and Citrulline

My Review of Performance Lab Pre Lab Pro: Is It Worth a Try?

Why Does Nitric Oxide Matter During Exercise?

Nitric oxide performs several functions relevant to sport.

It contributes to:

• blood-vessel dilation,
• blood-flow regulation,
• skeletal-muscle contractile function,
• mitochondrial efficiency,
• glucose handling,
• and oxygen utilization.

That sounds like a recipe for dramatically better performance.

But biological plausibility does not guarantee large real-world improvements.

The critical question is:

Do controlled human trials actually show better performance?

For dietary nitrate, the answer is:

sometimes, yes.

For citrulline:

sometimes—but much less consistently. Beetroot and Citrulline

What Does the Latest Nitrate Research Show?

One of the strongest current summaries is a 2025 umbrella review that examined 20 systematic reviews and meta-analyses.

Collectively, those reviews represented:

180 primary studies

and

2,672 participants.

Researchers found that nitrate supplementation significantly improved several outcomes, including:

• time to exhaustion,
• total distance covered,
• muscular endurance,
• peak power,
• and time to peak power.

But several other performance outcomes did not significantly improve.

That distinction matters.

Nitrate appears genuinely ergogenic.

But it is not a guaranteed performance enhancer for every exercise test. Beetroot and Citrulline

Does Beetroot Improve Endurance?

This is probably the most established application.

A systematic review and meta-analysis of 73 endurance studies involving more than 1,000 participants found nitrate supplementation improved:

• power output,
• time to exhaustion,
• and distance traveled.

However, there was no significant improvement in every outcome, including some time-trial measures.

This suggests nitrate may be particularly useful for increasing exercise capacity—how long someone can continue before exhaustion—rather than guaranteeing faster performance in every race format.

That difference is important. Beetroot and Citrulline

A supplement can improve a laboratory time-to-exhaustion test without automatically producing an equivalent improvement in a real race.

Does Beetroot Improve Strength?

Potentially—but the effect appears relatively small.

A systematic review and meta-analysis examining muscular performance found nitrate supplementation had:

a trivial but statistically significant effect on muscular strength

and

a small but significant effect on muscular endurance.

So nitrate appears more compelling for:

performing repeated work

than for dramatically increasing one-repetition maximal strength.

That makes sense physiologically. Beetroot and Citrulline

Improved muscle efficiency and blood flow may be more relevant when fatigue builds across repeated contractions.

What About Squats and Bench Press?

A meta-analysis specifically examining resistance-trained men found nitrate supplementation improved:

• repetitions to failure,
• mean power,
• and mean velocity

when squat and bench-press studies were combined.

It did not significantly improve:

• peak power,
• or peak velocity.

Again, this is a good example of why the phrase:

“Beetroot improves strength”

is too broad. Beetroot and Citrulline

A more defensible statement is:

Nitrate may modestly improve muscular endurance and some power/velocity outcomes during resistance exercise, particularly under repeated effort.

What About Muscle Power?

There is stronger evidence here.

An individual-participant meta-analysis of 19 studies involving 268 participants found that dietary nitrate increased maximal muscle power by approximately:

5% on average.

The effect was present with both acute and repeated supplementation, although the acute effect appeared larger in that analysis.

That finding is practically interesting.

A 5% change is not trivial in competitive sport.

But averages do not guarantee every athlete will respond the same way. Beetroot and Citrulline

How Much Nitrate Actually Works?

This is where the discussion becomes especially important.

Beetroot powder is not the same thing as nitrate dose.

A product can contain several grams of beetroot while providing relatively little actual nitrate.

The 2025 umbrella review found that improvements in time-to-exhaustion were more pronounced when participants consumed at least:

6 mmol nitrate per day

which equals approximately:

372 mg nitrate

and when supplementation continued for more than three days.

Other reviews commonly describe effective nitrate strategies in the approximate range of:

5–16.8 mmol

or roughly:

300–1,041 mg nitrate

often consumed 2–3 hours before exercise.

This does not mean 372 mg is a magical threshold below which nitrate does nothing.

It means performance research is generally conducted using hundreds of milligrams of actual nitrate, not merely hundreds or thousands of milligrams of beetroot powder. Beetroot and Citrulline

Why Standardized Nitrate Matters

Imagine two supplements.

Product A

Contains:

2,000 mg generic beetroot powder

but does not disclose nitrate concentration.

Product B

Contains:

1,000 mg standardized beetroot

providing a known amount of nitrate.

You cannot assume Product A delivers more active nitrate simply because the beetroot weight is larger.

This is why nitrate standardization is more useful than beetroot milligrams alone.

Pre Lab Pro at least discloses that its beetroot is standardized to approximately:

1.5%–2.75% natural nitrate.

That lets us perform a meaningful comparison. Beetroot and Citrulline

How Much Nitrate Is Actually in Pre Lab Pro?

Pre Lab Pro contains:

1,500 mg beetroot powder

standardized to:

1.5%–2.75% nitrate.

If those percentages apply directly to the 1,500 mg ingredient amount, that works out to approximately:

22.5–41.25 mg nitrate per scoop.

In molar terms, that’s roughly:

0.36–0.67 mmol nitrate.

That is far below the approximately:

6 mmol / 372 mg

associated with stronger time-to-exhaustion effects in the 2025 umbrella review.

Even two scoops would provide an estimated:

45–82.5 mg nitrate

or approximately:

0.73–1.33 mmol.

Again:

that does not prove the beetroot dose is useless.

The formula also contains citrulline and glutathione.

And nitrate dose-response relationships vary by outcome.

But it does mean the statement:

“Pre Lab Pro provides a research-level beetroot nitrate dose”

would require much more caution. Beetroot and Citrulline

The actual nitrate amount appears considerably lower than the quantities used in much of the dedicated nitrate-performance literature.

Does More Beetroot Automatically Mean More Nitrate?

No.

This is why comparing beetroot supplements by grams alone can be misleading.

A concentrated standardized extract might provide more nitrate per gram than ordinary beetroot powder.

But ultimately the useful number is:

actual nitrate delivered.

If the nitrate amount is not disclosed, performance claims become much harder to evaluate.

Pre Lab Pro deserves credit for disclosing its standardization. Beetroot and Citrulline

That transparency is useful even when the comparison raises questions about dose.

What About Citrulline?

L-citrulline is another popular nitric-oxide supplement.

It has an advantage over oral arginine because citrulline generally raises blood arginine more efficiently.

That makes it biologically attractive.

But performance research is inconsistent. Beetroot and Citrulline

Does Citrulline Improve Endurance?

Not convincingly based on current evidence.

A systematic review and meta-analysis examining citrulline and aerobic exercise found no significant improvement in:

• aerobic performance,
• rating of perceived exertion,
• oxygen kinetics,
• or lactate.

Another meta-analysis focusing on endurance outcomes similarly found no significant improvement in:

• time to exhaustion,
• or time-trial completion

after acute citrulline supplementation. Beetroot and Citrulline

So pure citrulline currently has a weaker endurance-performance case than dietary nitrate.

What About Citrulline for Resistance Training?

The evidence becomes somewhat more positive.

A meta-analysis examining acute citrulline malate supplementation found that:

6–8 g taken 40–60 minutes before resistance exercise

increased repetitions to failure by roughly:

3 repetitions on average

or approximately:

6% compared with placebo.

That’s a small but potentially meaningful effect.

However, this research used citrulline malate.

Pre Lab Pro uses L-citrulline combined with glutathione.

Those are not the same intervention. Beetroot and Citrulline

You should not automatically transfer the 6–8 g citrulline-malate findings to a 2 g L-citrulline dose.

What Does the Newer Citrulline Evidence Say?

A 2026 systematic review and meta-analysis included:

30 randomized trials

and

644 participants.

It found a small overall improvement in exercise performance from citrulline malate.

But the authors rated the certainty of evidence as:

low to very low

and concluded that reliable optimal:

• doses,
• timing,
• and target populations

still have not been established.

That is probably the best way to characterize citrulline currently:

plausible and potentially useful—but not universally effective.

Why Add Glutathione to Citrulline?

This is the specific strategy behind Pre Lab Pro’s Setria® Performance Blend.

The proposed idea is:

Citrulline increases arginine availability.

Arginine helps support nitric-oxide production.

Glutathione may help protect nitric oxide from oxidative degradation.

In theory, that could create a stronger or longer-lasting nitric-oxide response.

A human study found that combining L-citrulline with glutathione increased markers associated with nitric-oxide synthesis more than placebo.

This is biologically interesting. Beetroot and Citrulline

But improving nitric-oxide biomarkers is not automatically the same thing as improving running, lifting, or cycling performance.

That distinction becomes very important when we examine the Setria Performance Blend directly.

What Has Setria Performance Blend Actually Been Shown to Do?

A 2023 randomized, double-blind, placebo-controlled crossover study tested the same named Setria Performance Blend.

Participants received:

2 g L-citrulline

plus

200 mg glutathione

for eight days.

That totals exactly:

2,200 mg

—the same total blend weight currently listed in Pre Lab Pro.

This is one of the strongest ingredient-dose matches in the formula. Beetroot and Citrulline

What Did That Study Find?

Twenty-five trained men completed treadmill exercise tests at:

• 90%,
• 100%,
• and 110%

of peak velocity.

Researchers also measured:

• blood flow,
• vessel diameter,
• plasma citrulline,
• and plasma arginine.

The Setria blend significantly increased:

post-exercise blood flow

and increased circulating:

citrulline and arginine.

That sounds positive.

But now comes the most important result:

time to exhaustion did not significantly improve at any of the three exercise intensities.

The authors’ own conclusion was explicit:

the blend did not enhance time-to-exhaustion performance in these trained men.

It did improve post-exercise blood flow, which could potentially have implications for recovery, but a direct endurance-performance benefit was not demonstrated.

This is exactly why biomarkers and performance should not be treated as interchangeable. Beetroot and Citrulline

Does Setria Help Build Muscle?

Another trial investigated L-citrulline + glutathione during eight weeks of resistance training.

Seventy-five resistance-trained men were assigned to:

• citrulline + glutathione,
• citrulline malate,
• or placebo.

The study reported favorable body-composition findings with the combined supplement, including lean-mass changes, and found no concerning changes in clinical safety markers.

That is interesting.

But it should not be interpreted as:

“Taking Setria right before one workout instantly builds muscle.”

This was a chronic resistance-training study.

Muscle growth occurs over time. Beetroot and Citrulline

And the training program itself is a major part of the intervention.

Is Beetroot + Citrulline Better Than Either Alone?

You would expect two nitric-oxide pathways to be better than one.

Scientifically, that is plausible.

But human evidence is not yet strong enough to conclude that the combination is reliably superior.

A systematic review examining beetroot combined with other nutritional supplements found mixed results.

Some co-supplementation studies produced positive outcomes.

Others failed to outperform beetroot or placebo conditions.

More recently, a study of elite rowers using nitrate plus citrulline found no evidence of improved energy metabolism after one week of co-supplementation.

So:

more nitric-oxide ingredients ≠ automatically more performance.

The amount, timing, population, and exercise test still matter. Beetroot and Citrulline

Can Beetroot and Citrulline Give You a Better Pump?

Possibly.

A “pump” is not a formal performance outcome, but increased muscle blood flow is physiologically consistent with higher nitric-oxide availability.

Citrulline can increase circulating arginine.

Nitrate can increase nitric-oxide availability.

Setria Performance Blend has demonstrated greater post-exercise blood flow in one controlled trial.

So the biological rationale for a pump effect is reasonable. Beetroot and Citrulline

But remember:

pump is not the same as performance.

You can experience a stronger pump without becoming:

• stronger,
• faster,
• or able to perform meaningfully more work.

And a product that improves performance does not necessarily create a dramatic subjective pump. Beetroot and Citrulline

Why Timing Matters More for Beetroot Than Many Labels Suggest

This is another important point when evaluating pre-workouts.

Pre Lab Pro currently recommends:

1 scoop 30 minutes before exercise.

That timing makes sense for some of its ingredients, particularly caffeine.

But dietary nitrate research frequently uses much longer pre-exercise timing.

Reviews commonly report nitrate being taken approximately:

2–3 hours before exercise.

This is because nitrate must move through the nitrate–nitrite pathway before peak effects occur.

So Pre Lab Pro’s 30-minute general timing recommendation may not align perfectly with the timing used in many dedicated nitrate trials.

That does not prove the formula cannot work at 30 minutes. Beetroot and Citrulline

It means:

the caffeine and other ingredients may be operating on a different clock from the beetroot nitrate.

We will examine that issue in detail in Article #5.

Why Mouthwash Can Matter for Beetroot

This sounds strange, but it is scientifically relevant.

Conversion of dietary nitrate to nitrite depends partly on bacteria in the mouth.

Strong antibacterial mouthwash can interfere with those bacteria.

Research reviews therefore often advise avoiding antibacterial mouthwash around nitrate supplementation when trying to maximize nitrate-related effects.

This is a good example of how nitrate supplementation is more biologically complicated than:

“drink beetroot and nitric oxide goes up.” Beetroot and Citrulline

Who Responds Best to Dietary Nitrate?

Research suggests response can vary according to training status.

Highly trained endurance athletes sometimes show smaller effects than recreationally trained individuals.

One major meta-analysis found little clear benefit in the subgroup of highly trained endurance athletes.

Possible reasons include:

• already optimized vascular function,
• naturally higher nitric-oxide availability,
• better mitochondrial efficiency,
• and less room for supplementation to improve performance.

That does not mean elite athletes never respond.

It means the average response may be smaller. Beetroot and Citrulline

Does Nitrate Work for Women?

Female-specific evidence has historically been limited.

A 2025 systematic review and meta-analysis found nitrate supplementation produced a statistically significant improvement in power among healthy women but did not significantly improve:

• strength,
• or sprint performance.

The certainty of evidence ranged from low to moderate. Beetroot and Citrulline

This is useful because sports-supplement research has traditionally involved disproportionately male participants.

How Does Pre Lab Pro’s Nitric-Oxide Formula Compare With the Research?

Here is the most useful summary.

Ingredient	Pre Lab Pro	Research Context	Assessment
Beetroot powder	1,500 mg	Actual nitrate dose matters more than beetroot weight	Standardized, but nitrate amount appears relatively low
Estimated nitrate	~22.5–41.25 mg	Many studies use ~300–1,000+ mg nitrate	Considerably below typical dedicated nitrate research
Setria Performance Blend	2,200 mg	Human trial used exactly 2 g citrulline + 200 mg glutathione	Strong dose/form match
L-citrulline within Setria study	2 g	Citrulline-malate studies often use 6–8 g	Lower than many classic CitMal protocols, but different formulation
Glutathione	200 mg in Setria research	Human studies support NO-related biomarker effects	Plausible supportive role

This reveals something important.

Pre Lab Pro has one strong dose match:

Setria Performance Blend.

The published Setria trial used the same total 2,200 mg combination represented by:

2 g L-citrulline + 200 mg glutathione.

But the results were mixed:

blood flow improved

while

time-to-exhaustion performance did not.

The beetroot side is less convincing from a dose perspective.

The standardized nitrate concentration is useful. Beetroot and Citrulline

But the estimated actual nitrate intake appears far below typical ergogenic nitrate research ranges.

Could Citrulline Compensate for the Lower Beetroot Nitrate?

This is possible in theory.

But it has not been demonstrated.

Pre Lab Pro appears designed around two parallel nitric-oxide strategies:

pathway 1

beetroot → nitrate → nitrite → NO

pathway 2

citrulline → arginine → nitric-oxide synthase → NO

The formula also adds glutathione, which may affect nitric-oxide stability.

That is an interesting design.

But we currently cannot say:

“Because the citrulline is present, you only need a tiny amount of nitrate.”

There is no robust clinical evidence establishing that type of substitution.

Each ingredient should still be evaluated according to its own dose and evidence.

Does Pre Lab Pro Produce a “2X Nitric Oxide Surge”?

That phrase is part of the manufacturer’s positioning.

Scientifically, I would avoid repeating it as a measured product fact unless there is finished-product research showing exactly:

• nitric-oxide concentration before and after Pre Lab Pro,
• compared with placebo,
• using the complete formula.

The individual Setria ingredient has nitric-oxide-related research.

Beetroot has nitrate research.

But combining two NO-oriented ingredients does not mathematically prove:

2× nitric oxide.

That is marketing language rather than a conclusion established by the current evidence we reviewed.

Is Pre Lab Pro Underdosed for Nitric Oxide?

The answer needs nuance.

Beetroot nitrate

Relative to most dedicated nitrate-performance protocols:

yes, the estimated nitrate exposure appears low.

Citrulline + glutathione

The formula appears to use the same 2,200 mg Setria Performance Blend amount studied in humans.

That is a stronger dose match.

Finished product

There is not enough finished-product research to determine whether the combined Pre Lab Pro formula produces meaningful nitric-oxide or exercise-performance improvements beyond its individual ingredients.

So I would not describe the overall NO formula simply as:

underdosed

or

clinically dosed.

The more accurate description is:

mixed dose relevance.

Who Might Still Find This Formula Attractive?

Pre Lab Pro may make sense for someone who values:

• a lower-stimulant formula,
• transparent dosing,
• a clinically studied citrulline + glutathione blend,
• moderate caffeine,
• and multiple mechanisms rather than a single huge stimulant dose.

It may be less compelling if your primary goal is specifically to obtain a high-dose nitrate protocol similar to those used in beetroot performance trials.

Someone seeking that outcome would need to pay particular attention to the actual nitrate amount.

Frequently Asked Questions

The Bottom Line

Beetroot and citrulline are two of the most popular nitric-oxide ingredients in sports supplements.

Both make biological sense.

But their evidence is not identical.

Beetroot / nitrate

Dietary nitrate has the stronger overall performance case.

The best current evidence suggests modest benefits for:

• time to exhaustion,
• muscular endurance,
• total distance,
• peak power,
• and certain resistance-exercise outcomes.

But the amount of actual nitrate matters far more than the weight of beetroot powder.

Citrulline

L-citrulline reliably increases arginine availability.

But actual exercise-performance research is mixed.

Citrulline malate may modestly increase resistance-training repetitions, while meta-analyses of endurance exercise often show little or no benefit.

Citrulline + glutathione

The Setria Performance Blend used by Pre Lab Pro is especially interesting because the product’s 2,200 mg blend matches the dose used in human research.

That study showed:

better post-exercise blood flow

but

no significant improvement in time to exhaustion.

Pre Lab Pro’s beetroot

Its standardized beetroot is transparent, which is a positive.

But based on its 1.5%–2.75% nitrate standardization, one serving appears to provide only approximately:

22.5–41.25 mg nitrate.

That is substantially lower than the several-hundred-milligram nitrate doses commonly used in dedicated exercise-performance research.

So the most balanced interpretation is:

Pre Lab Pro uses a scientifically plausible dual nitric-oxide strategy, and its Setria dose closely matches human research, but its beetroot nitrate amount appears considerably lower than classic ergogenic nitrate protocols.

That does not make the formula ineffective.

It means its marketing claims should not be treated as interchangeable with research conducted using much larger nitrate doses.

For our complete product-specific assessment—including the caffeine strategy, nitric-oxide formula, ingredient doses, pros and cons, pricing, and who Pre Lab Pro is best suited for—see our full Pre Lab Pro review.