What Are Nitrate Supplements and How Do They Work?

Nitrate supplements are concentrated doses of inorganic nitrate, a compound found naturally in vegetables like beetroot, spinach, and amaranth, packaged as juices, powders, or tablets. They work by supplying the raw material your body uses to produce nitric oxide, a molecule that relaxes blood vessels, lowers blood pressure, and can reduce the oxygen cost of physical exercise. The conversion from dietary nitrate to nitric oxide depends on a surprisingly elegant relay between your salivary glands, the bacteria living on your tongue, and your stomach chemistry, and that relay is where things get interesting.

Where Nitrate Supplements Come From

Most nitrate supplements are made from dehydrated or concentrated vegetables, with beetroot being the dominant source. Beetroot contains nitrate at roughly 2,500 mg per kilogram, which makes it practical to concentrate into a small serving of juice or powder.¹ You can also get substantial nitrate from spinach (roughly 900 to 5,400 mg/kg in the leaves) and from amaranth species, sometimes marketed as “red spinach extract,” which can contain up to 8,800 mg/kg in the leaves.¹

Commercial products vary widely in their actual nitrate content. A product like Beet Elite, marketed for endurance, can deliver close to the full acceptable daily intake of nitrate in a single serving, while a milder option like Beet Boost provides around a fifth of that limit.² Some supplements also contain significant amounts of nitrite, a related but distinct compound. One cardiovascular supplement, Neo40, delivers over four times the acceptable daily intake of nitrite per tablet.² The difference matters for both effectiveness and safety, because nitrate and nitrite follow different routes once they enter the body.

How Your Body Turns Nitrate Into Nitric Oxide

Your body produces nitric oxide through two separate pathways. The first is an internal process where enzymes build it from the amino acid L-arginine. The second, which is the one nitrate supplements target, works from the outside in. You swallow nitrate, it enters your bloodstream, and then something counterintuitive happens: up to a quarter of that circulating nitrate gets actively pulled out of the blood by your salivary glands and concentrated into your saliva at levels 10 to 20 times higher than what is in your blood.³

Once nitrate is concentrated in saliva, bacteria living on the back of your tongue go to work. Species like Prevotella melaninogenica and Veillonella dispar use nitrate in their own metabolism, and as a byproduct, they reduce it to nitrite.⁴ When you swallow this nitrite-rich saliva, the acidic environment of your stomach converts some of it into nitric oxide and other related molecules. Nitrite also enters the bloodstream, where hemoglobin can convert it to nitric oxide under low-oxygen conditions.⁵ This second pathway is enhanced precisely when your body needs it most: during exercise, at altitude, or in tissues starved of oxygen.⁶

Why Mouthwash Can Cancel Out Your Supplement

Because the conversion of nitrate to nitrite depends entirely on oral bacteria, anything that wipes out those bacteria disrupts the whole chain. Chlorhexidine mouthwash, the antibacterial rinse commonly prescribed after dental procedures, destroys up to 94% of nitrate-reducing oral bacteria and cuts nitrate-to-nitrite conversion by about 85%.⁷ This is not a minor biochemical footnote. In a study of people being treated for high blood pressure, just three days of using antibacterial mouthwash raised systolic blood pressure by about 2 mmHg compared to a control period, alongside clear drops in salivary nitrite.⁸

The practical takeaway is straightforward: if you are using a nitrate supplement for blood pressure or exercise benefits, pairing it with antibacterial mouthwash is self-defeating. The mouthwash blocks the very first step the supplement needs to work. Animal research has confirmed that while mouthwash blocks the effects of nitrate, it does not block the effects of nitrite taken directly, because nitrite enters the pathway downstream of the bacteria.⁹ This distinction reinforces how central those tongue-dwelling microbes are to the process.

Effects on Exercise Performance

The most widely studied use of nitrate supplements is for exercise, and the evidence here is real but uneven. One of the landmark findings was that beetroot juice reduced the oxygen cost of moderate-intensity cycling by about 19% and extended time to exhaustion during hard efforts.¹⁰ Trained cyclists improved time-trial completion by roughly 3 to 4% in some studies, along with improvements in power output relative to oxygen use.¹¹

The mechanism behind these performance gains involves both efficiency and muscle contractile properties. Nitric oxide appears to increase the number of active connections between muscle fibers during contraction and speed up the rate at which those connections cycle, without increasing the peak force each connection generates.¹² A meta-analysis found small but statistically meaningful improvements in peak power output and mean power output during dynamic exercise after nitrate supplementation.¹³ One study also observed a roughly 6.5% increase in the optimal pedaling rate during maximal sprints, suggesting nitric oxide speeds up muscle shortening velocity.¹⁴

Why Elite Athletes See Smaller Benefits

One consistent pattern across the literature is that the fitter you already are, the less nitrate supplements seem to help. Low-fitness runners showed significantly lower oxygen cost at submaximal intensities after beetroot juice, while high-fitness runners did not.¹⁵ Well-trained cyclists who took high-dose beetroot juice for multiple days showed no change in exercise efficiency or oxygen uptake during moderate-intensity cycling.¹⁶ A study comparing endurance-trained cyclists with recreationally active controls found that even with a large acute dose of beetroot juice, neither group showed changes in oxygen consumption or blood pressure, though the trained cyclists did have a somewhat larger plasma nitrite increase.¹⁷

A large umbrella review tried to sort this out and found that the benefits split along population lines. Professional athletes derived small but meaningful muscular strength gains, while non-athletes saw improvements primarily in aerobic endurance. In both groups, the effect sizes were small.¹⁸ The likely explanation is that trained athletes already have highly optimized oxygen delivery and muscle efficiency, so there is less room for a dietary supplement to add anything. If you are a recreational exerciser looking for a modest edge, the evidence is more encouraging than if you are already competing at a high level.

Cardiovascular Effects Beyond Exercise

Nitrate supplementation reliably lowers blood pressure in the short term, though the size of the effect varies. A randomized trial in healthy adults found that beetroot juice reduced systolic blood pressure by 4 to 5 mmHg in men about six hours after drinking it.¹⁹ Inorganic nitrate capsules (potassium nitrate, rather than beetroot) similarly dropped systolic pressure by about 5 mmHg and improved arterial stiffness in healthy volunteers.²⁰

The vascular effects go beyond pressure readings. In healthy older men, a single dose of nitrate improved flow-mediated dilation of the femoral artery and reduced arterial wave reflection, both markers of how flexible and responsive blood vessels are.²¹ One study also looked at sympathetic nerve activity, the body’s “fight or flight” signaling to blood vessels, and found that beetroot juice reduced nerve firing rates compared to placebo, though blood pressure itself did not significantly change in that particular trial.²² Collectively, the cardiovascular picture suggests that nitrate helps blood vessels relax and reduces the workload on the heart, even if the blood pressure drop in any single study is modest.

Dosing and Timing

Getting the dose and timing right matters more than most supplement marketing suggests. A dose-response study found that plasma nitrite levels rise in proportion to the amount of nitrate consumed, peaking around two to three hours after ingestion. But exercise benefits only kicked in at doses of about 8 mmol of nitrate or more; a smaller dose of about 4 mmol raised blood levels of nitrite without producing measurable changes in oxygen cost or endurance.²³ Going above about 8 mmol did not add further performance improvement, suggesting a ceiling effect.²³

The current practical recommendation based on the research is roughly 5 to 9 mmol of nitrate per day, taken about two to two and a half hours before exercise, with supplementation periods ranging from a single dose up to about four weeks. Chronic supplementation at 6 mmol per day maintained the reduction in oxygen cost of exercise even up to 24 hours after the last dose, while a lower chronic dose of 3 mmol per day did not produce exercise benefits at all.²⁴ For blood pressure, even single acute doses show effects within a few hours, but the long-term blood pressure implications of daily nitrate supplementation over months or years are less well studied.

Nitrate, Nitrite, and Cancer Risk

The most common concern about nitrate supplements is cancer, and the story here requires separating nitrate from nitrite and both from nitrosamines. Nitrate itself, when consumed from plant sources, is associated with either no increased risk or a slightly reduced risk of gastric cancer. A review of the evidence found that dietary nitrate at levels below 600 mg per day correlated with a relative risk of stomach cancer below 1, meaning a possible protective effect. The authors attributed this largely to the other compounds that come along with vegetable-sourced nitrate, such as antioxidants and vitamins.²⁵

Nitrite and nitrosamines tell a different story. Dietary nitrite intake was associated with a relative risk of gastric cancer between roughly 1.1 and 1.5, and nitrosamines between about 1.0 and 1.8.²⁵ The source matters too. Research on kidney cancer found that nitrate and nitrite from animal sources, particularly processed meat, were positively associated with risk, while the same compounds from plant sources were not.²⁵ The likely explanation is that in the presence of protein (as in cured meats) and high heat, nitrite reacts with amino acids to form nitrosamines, which are the genuinely carcinogenic compounds. Vegetable nitrate, consumed with the plant’s own antioxidants, tends not to undergo that same conversion.

The acceptable daily intake for nitrate is 3.7 mg per kilogram of body weight according to European and international food safety authorities.²⁶ For a 70-kg adult, that is about 260 mg per day. The reality is that people who eat a lot of vegetables often exceed this limit, and supplementation pushes intake substantially higher. The regulatory framework has not caught up with the supplementation literature, and the long-term safety data on chronic high-dose nitrate from supplements, as opposed to food, remain thin.

Performance at High Altitude

Because the nitrate-to-nitric-oxide pathway ramps up under low-oxygen conditions, researchers have tested whether supplementation can offset the performance penalty of altitude. The results are mixed. One study simulating moderate altitude (3,000 m) and very high altitude (4,300 m) found that beetroot juice reduced oxygen consumption during steady-state exercise, raised blood oxygen saturation, and improved 3-km time-trial performance by roughly 4% at both simulated elevations.²⁷ However, a field study that took participants to actual high altitude found no significant changes in resting oxygen saturation, cardiorespiratory variables, or acute mountain sickness scores with nitrate supplementation.²⁸

The discrepancy likely reflects the difference between a controlled lab simulation, where exercise intensity and conditions are tightly managed, and a real expedition, where many other stressors are at play. For now, the altitude evidence is promising enough to investigate further but not strong enough to recommend nitrate supplements as a reliable altitude aid.

The Diabetes and Metabolic Health Question

Animal studies have generated excitement about nitrate’s potential to improve insulin signaling, glucose uptake, and the metabolic dysfunction associated with type 2 diabetes.²⁹ In rodent models, inorganic nitrate and nitrite improved vascular function, blood pressure regulation, and fat metabolism alongside diabetes-related markers. The problem is that these findings have not translated to humans in the trials conducted so far. A clinical trial giving 7.5 mmol of nitrate per day for two weeks to people with type 2 diabetes raised plasma nitrite as expected but produced no improvement in blood pressure, endothelial function, or insulin sensitivity.³⁰ The gap between the animal data and the human data remains wide, and as one review put it, the metabolic effects of nitrate in humans with diabetes are still awaiting thorough testing.³¹

Sex Differences and the Role of Estrogen

Most nitrate supplementation research has been conducted in men, and the limited data in women suggest the response may differ. Estrogen itself boosts nitric oxide availability through the body’s internal enzymatic pathway, and estrogen levels fluctuate across the menstrual cycle. A study examining the effects of nitrate supplementation across the menstrual cycle found that while plasma nitrite levels rose as expected in women who took beetroot juice, calculated maximal power and maximal velocity actually worsened with supplementation, regardless of menstrual cycle phase.³²

This is a single study and too early to draw firm conclusions, but it raises the possibility that in people who already have elevated nitric oxide availability due to estrogen, additional nitrate may not help and could even be counterproductive in certain performance domains. The broader issue is that the supplement industry and much of the research has treated nitrate as a one-size-fits-all intervention, when the underlying biology suggests the response is highly individual.

Cognitive Effects in Older Adults

Because nitric oxide influences blood flow in the brain as well as in the muscles, there has been interest in whether nitrate supplements can sharpen thinking, particularly in aging. So far, the evidence is thin. A study in healthy older adults found that while dietary nitrate lowered resting blood pressure and improved the speed at which oxygen uptake adjusted during treadmill walking, it did not improve walking performance, brain metabolite levels, or cognitive function on any of the tests administered.³³ The simulated altitude study also measured cognitive function and found no benefit from beetroot juice.²⁷ The cardiovascular and muscular evidence is much stronger than anything currently available for brain benefits, and marketing that positions nitrate as a cognitive enhancer is running ahead of the science.