Dietary nitrate (beetroot) vs L-citrulline
Two different routes to the same molecule, nitric oxide — one from the diet via oral bacteria, the other bypassing the gut's first-pass metabolism of arginine entirely.
Short answer
Both are supplements with some human trials behind them, so what separates dietary nitrate and L-citrulline is the goal. For a reader focused on blood pressure, nitric oxide, blood flow and endurance, dietary nitrate is the relevant choice; L-citrulline is marketed for nitric oxide, pumps, training volume and blood pressure.
Dietary nitrate (beetroot)
Beet juice, beetroot powder
A well-mapped NOS-independent route to nitric oxide with a genuine ~4–5 mmHg systolic effect and a small endurance benefit in recreationally trained people — but nothing in elite athletes, no hard outcomes, and an effect antibacterial mouthwash can abolish.
Full Dietary nitrate (beetroot) evidence reviewL-citrulline
Citrulline, citrulline malate
The central pharmacology survives scrutiny — citrulline bypasses intestinal arginase and raises plasma arginine better than arginine itself — but the outcomes are consistently small, and most labels hide the malate ratio.
Full L-citrulline evidence reviewDietary nitrate (beetroot) vs L-citrulline: head to head
- FDA status / approved use
Dietary nitrate (beetroot)
Sold as foods and dietary supplements; not FDA-approved for any conditionL-citrulline
Sold as a supplement- Marketed for
Dietary nitrate (beetroot)
Blood pressure, nitric oxide / blood flow, enduranceL-citrulline
Nitric oxide / pumps, training volume, blood pressure, erectile function- Outcome areas
Dietary nitrate (beetroot)
Cardiovascular; Exercise performance / enduranceL-citrulline
Exercise performance / endurance; Cardiovascular; Sexual health / libido- Evidence grade
Dietary nitrate (beetroot)
Clinical dataL-citrulline
Clinical data- How it works
Dietary nitrate (beetroot)
Mouth bacteria convert nitrate to nitrite, which the body turns into nitric oxideL-citrulline
Converted to arginine in the kidney, raising arginine for nitric oxide production- Route and dosing
Dietary nitrate (beetroot)
Oral beet juice or nitrate shot, about 2–3 hours before exerciseL-citrulline
Oral, 6 to 8 g citrulline malate taken before training- Headline human result
Dietary nitrate (beetroot)
Systolic blood pressure around 4–5 mmHg lower in a meta-analysis of short randomized trialsL-citrulline
About 3 extra repetitions to failure (pooled SMD about 0.16 to 0.20) across three meta-analyses; certainty low to very low- Strongest evidence
Dietary nitrate (beetroot)
Siervo 2013 meta-analysis, J NutrDietary nitrate (beetroot) evidence reviewPubMed 23596162L-citrulline
Schwedhelm 2008 crossover PK/PD, Br J Clin PharmacolL-citrulline evidence reviewPubMed 17662090- Key safety signal
Dietary nitrate (beetroot)
Additive with blood-pressure medication; interacts with nitrates and PDE5 inhibitorsL-citrulline
No side effects reported at single doses up to 15 g- How it is obtained
Dietary nitrate (beetroot)
Over the counter as a dietary supplementL-citrulline
Over the counter as a dietary supplement
| Dietary nitrate (beetroot) | L-citrulline | |
|---|---|---|
| FDA status / approved use | Sold as foods and dietary supplements; not FDA-approved for any condition | Sold as a supplement |
| Marketed for | Blood pressure, nitric oxide / blood flow, endurance | Nitric oxide / pumps, training volume, blood pressure, erectile function |
| Outcome areas | Cardiovascular; Exercise performance / endurance | Exercise performance / endurance; Cardiovascular; Sexual health / libido |
| Evidence grade | Clinical data | Clinical data |
| How it works | Mouth bacteria convert nitrate to nitrite, which the body turns into nitric oxide | Converted to arginine in the kidney, raising arginine for nitric oxide production |
| Route and dosing | Oral beet juice or nitrate shot, about 2–3 hours before exercise | Oral, 6 to 8 g citrulline malate taken before training |
| Headline human result | Systolic blood pressure around 4–5 mmHg lower in a meta-analysis of short randomized trials | About 3 extra repetitions to failure (pooled SMD about 0.16 to 0.20) across three meta-analyses; certainty low to very low |
| Strongest evidence | Siervo 2013 meta-analysis, J NutrDietary nitrate (beetroot) evidence reviewPubMed 23596162 | Schwedhelm 2008 crossover PK/PD, Br J Clin PharmacolL-citrulline evidence reviewPubMed 17662090 |
| Key safety signal | Additive with blood-pressure medication; interacts with nitrates and PDE5 inhibitors | No side effects reported at single doses up to 15 g |
| How it is obtained | Over the counter as a dietary supplement | Over the counter as a dietary supplement |
marks a row where the two differ. “Not established” marks a cell the available evidence does not answer. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.
- Clinical data:
- Tested in humans — but investigational, discontinued, or proven only on a surrogate marker (not the marketed outcome).
Our verdict
Both raise nitric oxide, but by genuinely different pathways: dietary nitrate goes nitrate→nitrite→NO via oral bacteria (killed outright by antibacterial mouthwash), while citrulline is absorbed intact and converted to arginine in the kidneys, sidestepping the gut enzyme that destroys swallowed arginine. Nitrate's blood-pressure effect is slightly better characterized; citrulline's ergogenic case is real but modest, mostly a few extra reps rather than a dramatic performance change. Both effects shrink toward zero in elite athletes.
Dietary nitrate (beetroot) fits if
Blood pressure is the primary target, or a mouthwash interaction being a real-world concern rules out the nitrate route.
L-citrulline fits if
Training performance and pumps are the goal specifically, and you want the route that isn't vulnerable to oral bacteria.
Dietary nitrate (beetroot) vs L-citrulline: common questions
- Is either dietary nitrate or L-citrulline FDA-approved?
- No. Dietary nitrate is sold as foods and dietary supplements; not FDA-approved for any condition. L-citrulline is sold as a supplement.
- Which has stronger human evidence, dietary nitrate or L-citrulline?
- Neither clearly. Both have human clinical data. The key source for dietary nitrate is Siervo 2013 meta-analysis, J Nutr; for L-citrulline, it is Schwedhelm 2008 crossover PK/PD, Br J Clin Pharmacol.
- What are the main safety concerns with dietary nitrate and L-citrulline?
- Dietary nitrate is additive with blood-pressure medication; interacts with nitrates and PDE5 inhibitors. With L-citrulline, no side effects reported at single doses up to 15 g.
Key studies behind each
Dietary nitrate (beetroot)
- Lundberg JO, Weitzberg E, Gladwin MT. (2008). The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics. Nat Rev Drug Discov. PubMed 18167491
- Govoni M, Jansson EÅ, Weitzberg E, Lundberg JO. (2008). The increase in plasma nitrite after a dietary nitrate load is markedly attenuated by an antibacterial mouthwash. Nitric Oxide. PubMed 18793740
- Kapil V, Haydar SM, Pearl V, Lundberg JO, et al. (2013). Physiological role for nitrate-reducing oral bacteria in blood pressure control. Free Radic Biol Med. PubMed 23183324
- Burleigh MC, Liddle L, Monaghan C, Muggeridge DJ, et al. (2018). Salivary nitrite production is elevated in individuals with a higher abundance of oral nitrate-reducing bacteria. Free Radic Biol Med. PubMed 29550328
L-citrulline
- Schwedhelm E, Maas R, Freese R, Jung D, Lukacs Z, Jambrecina A, Spickler W, Schulze F, Böger RH. (2008). Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. Br J Clin Pharmacol. PubMed 17662090
- Castillo L, deRojas TC, Chapman TE, Vogt J, Burke JF, Tannenbaum SR, Young VR. (1993). Splanchnic metabolism of dietary arginine in relation to nitric oxide synthesis in normal adult man. Proc Natl Acad Sci U S A. PubMed 8419922
- Wu G, Morris SM Jr. (1998). Arginine metabolism: nitric oxide and beyond. Biochem J. PubMed 9806879
- van de Poll MC, Siroen MP, van Leeuwen PA, Soeters PB, Melis GC, Boelens PG, Deutz NE, Dejong CH. (2007). Interorgan amino acid exchange in humans: consequences for arginine and citrulline metabolism. Am J Clin Nutr. PubMed 17209193
The full evidence reviews
- Beetroot supplements and dietary nitrate: what the evidence actually supports
The nitrate→nitrite→nitric oxide pathway is real, and so are the blood-pressure and endurance effects — but they're modest, they vanish in elite athletes, product labels hide the dose, and antibacterial mouthwash can abolish the whole thing.
Updated August 2026
- L-citrulline: the evidence, the dose, and the citrulline malate problem
Oral citrulline really does raise plasma arginine better than oral arginine — that part is solid. The performance effect is about three extra reps, the blood-pressure data rest on eight small trials, and most labels won't tell you how much citrulline you're actually getting.
Updated August 2026