Nitric Oxide and Blood Pressure: Human Trials, Benefits and Risks

Can nitric oxide supplements lower blood pressure? Some forms of dietary nitrate and beetroot juice produce modest improvements in selected human trials. That finding does not mean every nitric-oxide booster has the same effect, or that increasing a saliva-strip reading treats hypertension. The relevant questions are which substance was tested, which patients were studied, how blood pressure was measured and whether the effect persisted.

How nitric oxide influences blood pressure

Endothelial nitric oxide synthase converts L-arginine into nitric oxide in the vessel wall. Nitric oxide then activates soluble guanylate cyclase in vascular smooth muscle, increasing cyclic GMP and supporting relaxation. Dietary nitrate provides an alternative route: nitrate is concentrated in saliva, reduced by oral bacteria to nitrite and may undergo further conversion to nitric oxide under certain physiological conditions. These pathways help explain why nutritional interventions are studied; biology alone, however, cannot determine a supplement's clinical benefit.

What the 2025 dietary-nitrate meta-analysis found

A 2025 systematic review and dose-response meta-analysis pooled 75 randomized trials involving 1,823 participants. It found that greater dietary nitrate exposure raised plasma nitrate and nitrite and was associated with small average reductions in blood pressure. The modeled effects differed by acute, short-term and medium-term follow-up. A pooled effect drawn from diverse nitrate sources and populations should not be converted into a precise expected reduction for an individual or a proprietary brand.

Beetroot juice in people with hypertension: a clinically focused review

The 2024 Grönroos meta-analysis included 11 trials involving 349 participants with hypertension. The pooled difference in clinic systolic blood pressure was −5.31 mmHg compared with control (95% confidence interval −7.46 to −3.16). Its authors graded certainty as low, found moderate-to-high heterogeneity and reported no statistically clear improvement in clinic diastolic or 24-hour ambulatory blood pressure. The distinction matters: a favorable clinic average is not the same as consistent around-the-clock blood-pressure control.

Positive and neutral randomized trials

A 2015 four-week randomized trial involving 68 adults with hypertension reported improvements in clinic, home and 24-hour ambulatory measures with nitrate-rich beetroot juice compared with nitrate-depleted juice. Yet other studies have not replicated such results in every group. In a 2015 crossover trial, 27 adults already receiving hypertension treatment had clear changes in nitrate metabolites without improvements in home or 24-hour pressure. Another 2024 study in 15 older adults with treated hypertension was neutral for blood pressure and vascular function over four weeks. These trials do not cancel one another; they show why baseline health, concurrent medication and intervention design affect interpretation.

Beetroot powder is not automatically equivalent to beetroot juice

Most persuasive hypertension trials used controlled nitrate doses delivered in beetroot juice or specific inorganic-nitrate preparations. Commercial beet powders can vary substantially in nitrate content by growing conditions, processing, serving size and standardization. A gram amount of beetroot powder does not translate into a reliable nitrate dose unless the manufacturer provides independent assay results. Our separate guide to beetroot powder and blood pressure examines that evidence gap.

What about L-arginine and L-citrulline?

Arginine provides the substrate for nitric-oxide synthase, whereas citrulline is converted into arginine after absorption. A 2022 review of randomized L-arginine trials reported average reductions in blood pressure, although doses, baseline patient groups and follow-up varied. L-citrulline analyses have produced mixed conclusions from small overlapping trial pools; improved plasma arginine is not itself a clinically meaningful endpoint. Neither precursor should be prescribed as a universal substitute for evidence-based hypertension care.

Can Nitralis lower blood pressure?

Its published 85-person pilot reported higher semi-quantitative salivary strip readings after 30 days but did not measure blood pressure. The wider beetroot and nitrate literature supplies mechanistic context, not a product-specific blood-pressure effect. Its 400 mg/day trial intervention also differs from the current 800 mg daily retail suggestion.

Safety with prescribed medication

Concentrated nitrate supplements may modestly lower pressure in some people, so combining them with antihypertensive medication can require a clinician's assessment and monitoring. Prescription organic nitrates must not be combined with PDE5 inhibitors such as sildenafil; this established drug contraindication should be distinguished from dietary nitrate chemistry. High-dose arginine after myocardial infarction also raises concern following the VINTAGE MI trial. Do not stop medication, ignore symptoms or substitute supplements for clinical treatment. See our drug-interaction guide.

What would change the evidence?

Larger independent trials with standardized product composition, sufficient duration, consistent home and ambulatory BP measurement and detailed medication subgroup analysis would tell us more. Hard outcomes such as stroke or cardiovascular events cannot presently be inferred from a short-term change in nitric-oxide metabolites. Blood-pressure evaluation and treatment remain established healthcare priorities.

Frequently asked questions

How much will nitric oxide supplements lower my pressure?

There is no defensible universal number. The −5.31 mmHg result describes a low-certainty clinic systolic average from particular beetroot-juice trials in people with hypertension, not an expected response to every supplement.

Does an increase in salivary nitric oxide prove better blood pressure?

No. Salivary colorimetric strips are indirect, semi-quantitative markers and do not measure your ambulatory blood pressure or endothelial function.

Can I use beetroot instead of medication?

No. Consult your clinician if you wish to incorporate a standardized dietary intervention alongside prescribed treatment; do not replace your regimen on the basis of small supplement trials.

Research sources

• Norouzzadeh et al., 2025 — 75-trial dietary-nitrate meta-analysis
• Grönroos et al., 2024 — 11-trial beetroot hypertension synthesis
• Kapil et al., 2015 — Four-week hypertension RCT
• Bondonno et al., 2015 — Neutral treated-hypertension RCT
• Fejes et al., 2024 — Neutral four-week crossover study