Quick answer: Dietary nitrate, often delivered through beetroot products, has improved some exercise outcomes in research. Benefits are not consistent across every endpoint. Beetroot and L-citrulline use different pathways, and the nitrate studies cited here do not establish benefits for L-citrulline products or treatment of cardiovascular disease.
Why nitric oxide appears on supplement labels
Nitric oxide is involved in vascular signaling. Supplements sold as “nitric oxide boosters” generally supply precursors or other ingredients rather than nitric oxide itself. Dietary nitrate and amino-acid products are distinct categories. A shared marketing phrase does not make their formulations, evidence or expected effects interchangeable.
It is especially important to separate an exercise-performance claim from a treatment claim. An improvement in power output during a research test does not show that a supplement prevents heart attacks, treats high blood pressure or replaces prescribed care.
What nitrate studies actually measured
A 2021 systematic review and meta-analysis included 73 studies involving 1,061 adults. Dietary nitrate improved pooled power output, time to exhaustion and distance traveled. It did not significantly improve time-trial performance, perceived exertion or work done, and it did not improve VO2max. These mixed results make a blanket “better endurance” promise too broad.
A 2023 review of short-duration, high-intensity exercise included 27 studies in the systematic review and 23 in the meta-analysis. It found small positive effects on some outcomes, including mean power output and distance in an intermittent recovery test. Results from a particular exercise test should be described as that result, not as a guaranteed advantage for every athlete.
The reviews pool study conditions and products. They are not clinical trials of every beetroot powder or chewable sold today. Their findings do not establish an optimal dose for an individual shopper or certify a commercial product's nitrate content.
L-citrulline requires its own evidence
L-citrulline is an amino acid used in a different nitric-oxide-related pathway. Evidence about dietary nitrate cannot be transferred to it. Likewise, an ingredient-only result cannot automatically be transferred to a blend containing citrulline, arginine and several other ingredients.
This explainer does not establish a citrulline treatment or performance benefit from the nitrate studies above. When reading a product claim, look for human research that matches the ingredient form, amount, population and outcome being claimed.
Compare the measured ingredient, not the marketing name
- Beetroot products: Look for declared nitrate content when the intended comparison is with nitrate research. A gram weight of beetroot powder alone does not tell you the nitrate dose.
- Citrulline products: Distinguish L-citrulline from blends and compare the amount per serving. Do not assume a blend's total weight is its citrulline content.
- Sport testing: If a particular sport certification matters to you, verify the exact product in the certifier's current listing rather than relying on a brand-wide claim.
- Personal suitability: Ask a pharmacist or clinician to review the exact formula if you have cardiovascular disease or take medicines affecting blood pressure.
Common questions
Does every beetroot supplement have the same nitrate content?
No comparison can be made from the name alone. The exact label and any product-specific testing matter; a product without declared nitrate content cannot be assumed to match a study.
Will a nitric oxide supplement improve every workout?
No. The cited reviews found mixed outcomes, including no significant improvement in some common performance measures. Individual results may differ.
Can I use these products instead of cardiovascular treatment?
The exercise studies do not support that substitution. Discuss a diagnosed condition and any proposed supplement with your treating professional.
Sources and evidence
- 2021 dietary nitrate and endurance exercise systematic review — 73 studies; mixed performance endpoints.
- 2023 dietary nitrate and high-intensity exercise systematic review — small benefits for some outcomes, not a general treatment claim.
Prepared with AI assistance by Apotheca Editorial. Sources checked September 29, 2026. This is an educational explainer, not a systematic review or individualized medical advice. No named clinical review is recorded for this revision. Read our editorial standards.