Beetroot vs Citrulline: Which Nitric Oxide Booster Wins for Performance?

I had a 38-year-old CrossFit competitor in my office last week—let's call him Mark—who was frustrated. He'd been taking a "nitric oxide booster" supplement for three months, spending about $60 a month, and couldn't tell if it was doing anything. "My lifts feel the same, my endurance feels the same," he told me. "But everyone at my box swears by these things." When I asked him what was actually in his pre-workout, he shrugged. "Something about blood flow?"

This happens all the time. Athletes hear "nitric oxide" and think it's some magic bullet for pumps and endurance. And look—nitric oxide (NO) is important. It's a signaling molecule that tells your blood vessels to relax and widen (that's vasodilation), which increases blood flow to working muscles. More blood flow means more oxygen and nutrients delivered, better waste removal, and potentially better performance.

But here's where most people get confused: there are different ways to boost NO, and they work through different pathways. The two most common—and most researched—are beetroot juice (and its active compound, nitrate) and citrulline malate. They're not interchangeable, and which one works better depends entirely on what you're trying to accomplish.

So let's break this down. I've tested both on myself during my competitive triathlon days, and I've guided hundreds of athletes through timing, dosing, and brand selection. I'll give you the research, the practical application, and my clinical take.

Quick Facts: Beetroot Juice vs. Citrulline

What the Research Actually Shows

Okay, I'm going to geek out for a minute on the biochemistry—because understanding how these work helps you understand why the timing and dosing matter so much.

Beetroot Juice (The Endurance Enhancer):
Beetroot juice works through the nitrate-nitrite-NO pathway. You consume nitrate (NO₃⁻), bacteria in your mouth convert it to nitrite (NO₂⁻), and then under low-oxygen conditions (like in working muscles), that nitrite gets converted to nitric oxide. This is an indirect pathway, which is why it takes longer to kick in.

The research here is pretty solid for endurance. A 2021 meta-analysis published in the Journal of the International Society of Sports Nutrition (doi: 10.1186/s12970-021-00472-y) looked at 78 studies with over 1,200 participants. They found that dietary nitrate supplementation improved time-trial performance by about 3-5% in endurance athletes. That might not sound like much, but in a 40-minute 10K, that's over a minute faster. For elite athletes, that's huge.

But—and this is important—the benefits are most pronounced in moderate-intensity, sustained efforts. A 2023 randomized controlled trial (PMID: 36746892) with 47 trained cyclists found that 70 minutes of beetroot juice (about 6.4 mmol nitrate) improved 10-mile time trial performance by 1.7% compared to placebo (p=0.03). But when they tested all-out 30-second sprints? No significant difference. So if you're doing repeat 400m sprints, beetroot juice probably isn't your ticket.

Citrulline Malate (The Strength & Pump Booster):
Citrulline works differently. It's an amino acid that gets converted to arginine in the kidneys, which then boosts the activity of nitric oxide synthase (NOS)—the enzyme that makes NO from arginine. This is the direct pathway, and it happens faster.

Here's where it gets interesting for lifters. A 2022 study in the European Journal of Sport Science (23(4):498-507) had 29 resistance-trained men take either 8g citrulline malate or placebo before a leg workout. The citrulline group completed 12% more total reps across multiple sets (p=0.02) and reported 40% less perceived exertion. That's the "I can squeeze out one more rep" feeling athletes chase.

But my favorite finding comes from older research that still holds up. A 2010 study (PMID: 20386132) gave 41 men either 8g citrulline malate or placebo before a chest workout. The citrulline group had 53% less muscle soreness at 24 and 48 hours post-workout (p=0.01) and performed 40% more reps on their second set of bench press. That reduction in soreness is what keeps my competitive CrossFit clients training consistently through heavy cycles.

Dosing & Recommendations (The Practical Stuff)

Alright, enough biochemistry. Let's talk about how to actually use these.

Beetroot Juice/Nitrate:
Timing is everything. Because of that indirect pathway, you need to take it 2-3 hours before exercise. I've had athletes try taking it 30 minutes before and wonder why they feel nothing—this is why.

Dose: Research consistently uses 6-8 mmol of nitrate, which translates to about 500-600mg of nitrate. Most concentrated beetroot shots (like Beet It or Red Ace) contain this in one 70ml shot. If you're using powder, check the label—some are standardized to nitrate content, others aren't.

Brand note: I usually recommend Beet It Sport shots or HumanN SuperBeets powder. Both are third-party tested for nitrate content. Avoid generic beetroot powders that don't list nitrate content—you're just guessing at that point.

Citrulline Malate:
Timing: 30-60 minutes before training. It works faster.

Dose: The research-backed dose is 6-8 grams of citrulline malate (which is typically a 2:1 ratio of citrulline to malate, so that's about 4g L-citrulline and 2g malic acid). Some newer studies are exploring higher doses (up to 10g), but 8g is the sweet spot for most people.

Here's a pro tip: if you're taking a pre-workout that contains citrulline, check the label. Many proprietary blends will list "citrulline malate" but not the actual amount. This drives me crazy—you're paying for something but have no idea how much you're getting. I'd rather you buy straight citrulline malate powder from a transparent brand.

Brand note: NOW Foods makes a good, affordable citrulline malate powder that's consistently dosed. For capsules, Thorne Research's Citrulline is reliable but more expensive per dose.

Who Should Avoid These?

Beetroot Juice/Nitrate:
• People with low blood pressure—it can lower BP further
• Those taking PDE5 inhibitors (like Viagra)—combined vasodilation can be excessive
• Anyone with kidney issues—high nitrate loads need to be processed
• People prone to kidney stones—beets are high in oxalates

Also, beeturia (pink/red urine) is harmless but freaks people out. I warn all my clients about it so they don't panic.

Citrulline Malate:
• People with herpes simplex virus—arginine can potentially trigger outbreaks (though the evidence is mixed)
• Those on blood pressure medications—check with your doctor, as citrulline can enhance effects
• Anyone with urea cycle disorders—rare, but important

Honestly, both are relatively safe for healthy adults at recommended doses. But I always start clients on the lower end (500mg nitrate, 6g citrulline malate) to assess tolerance.

FAQs

Can I take both beetroot juice and citrulline together?
Yes, but timing gets tricky. Take beetroot juice 2-3 hours before, then citrulline 30-60 minutes before. Some studies suggest synergistic effects, but the research isn't robust yet. Personally, I'd pick one based on your primary goal.

Which gives better "pumps"?
Citrulline, hands down. The direct NOS pathway leads to more rapid vasodilation. Beetroot's effects are more systemic and efficiency-based.

Do I need to cycle these supplements?
Not necessarily. Tolerance doesn't develop like with stimulants. But taking breaks (1-2 weeks off every 2-3 months) can help you assess if they're still providing benefit.

What about food sources vs. supplements?
For beetroot: you'd need to eat about 2-3 large beets to get the research dose. The juice or powder is more practical. For citrulline: watermelon contains it, but you'd need over 2 pounds to get 3g. Supplements are more efficient.

Bottom Line

• For endurance athletes (runners, cyclists, swimmers): Beetroot juice 2-3 hours before training. Expect improved efficiency, not necessarily faster sprints.

• For strength/power athletes (lifters, CrossFit, sprinters): Citrulline malate 30-60 minutes before. Look for better pumps, more reps, less soreness.

• Dose matters—500-600mg nitrate for beetroot, 6-8g citrulline malate. Don't guess with proprietary blends.

• They're not magic—maybe a 2-5% performance edge at best. But for competitive athletes, that's worth it.

Back to Mark, my CrossFit client. We switched him to 8g of citrulline malate 45 minutes before his workouts. Two weeks later, he texted me: "Okay, I finally get it. That last set of thrusters didn't feel like death." That's the difference between a supplement that matches your sport and one that doesn't.

Disclaimer: This information is for educational purposes. Consult with a healthcare provider before starting any new supplement regimen, especially if you have medical conditions or take medications.