How Beets Increase Nitric Oxide and Affect the Body

Beets raise nitric oxide levels through a surprisingly indirect route: the nitrate in beetroot is swallowed, absorbed, concentrated in your saliva, converted to nitrite by bacteria on your tongue, and then further reduced to nitric oxide in your stomach and bloodstream. This chain of events, sometimes called the enterosalivary pathway, leads to measurable drops in blood pressure, improved blood vessel flexibility, and enhanced exercise efficiency. But the effects reach further than most people expect, touching everything from platelet stickiness to how muscles use oxygen at altitude.

The Pathway From Beet to Nitric Oxide

Your body has two ways to make nitric oxide. The first is an enzyme-driven process that uses the amino acid L-arginine as raw material and requires oxygen. The second is the dietary nitrate pathway, which works differently and becomes especially active when oxygen is scarce. Beets exploit that second pathway.

When you drink beetroot juice or eat cooked beets, the inorganic nitrate they contain is absorbed quickly in the upper gut. About a quarter of that circulating nitrate gets pulled out of the blood by your salivary glands and concentrated in saliva at levels roughly 20 times higher than in plasma.¹ Bacteria living on the back of your tongue then reduce that nitrate to nitrite. Once you swallow the nitrite-rich saliva, the acidic environment of your stomach and a series of enzymatic reactions in blood and tissues convert it into nitric oxide and related signaling molecules. The whole loop, from swallowing to usable nitric oxide, takes roughly two to three hours to peak in the blood.

One implication of this pathway that catches people off guard is that it is entirely dependent on oral bacteria. Without those microbes performing the first reduction step, dietary nitrate stays as nitrate and never becomes nitric oxide.

Why Your Mouthwash Matters

Because the conversion from nitrate to nitrite hinges on bacteria in your mouth, anything that kills those bacteria short-circuits the process. Antibacterial mouthwash containing chlorhexidine has been shown to blunt the rise in plasma nitrite that normally follows a nitrate-rich meal and weaken the blood pressure reduction that comes with it.² Stronger rinses cause more disruption. In one study, increasing strengths of mouthwash produced a stepwise drop in both plasma and salivary nitrite after a nitrate load, effectively eliminating the beneficial effects on blood pressure.³

If you are eating beets specifically for cardiovascular or performance benefits, using a strong antibacterial mouth rinse around the same time may cancel out much of what you are trying to achieve. This does not mean you should skip oral hygiene, but it is worth knowing that the timing and type of rinse can matter.

Blood Pressure Effects

The blood pressure lowering effect of beetroot juice is one of the most consistently documented outcomes in this area. A systematic review and meta-analysis of supplementation trials found that beetroot juice and inorganic nitrate were associated with a reduction in systolic blood pressure of about 4 to 5 mmHg.⁴ That may not sound dramatic, but at a population level, a sustained drop of that size is linked to meaningful reductions in heart disease and stroke risk. The effect is more pronounced for systolic pressure (the top number) than diastolic.

A more recent meta-analysis focusing specifically on people with hypertension found a similar story: beetroot juice lowered systolic blood pressure by roughly 5 mmHg compared to placebo across eleven trials, though the effect on diastolic pressure and 24-hour blood pressure monitoring was not significant.⁵ The heterogeneity between studies was moderate to high, meaning that results varied quite a bit depending on the study population, dose, and duration. In practice, some people respond more than others.

Beyond Blood Pressure: How Beets Affect Blood Vessels

Nitric oxide’s primary job in the cardiovascular system is telling the smooth muscle cells in artery walls to relax, which widens the vessel and lets blood flow more freely. When researchers test this directly by measuring how well an artery expands in response to increased blood flow, a metric called flow-mediated dilation, beetroot supplementation tends to improve it. A systematic review found that inorganic nitrate and beetroot consumption were associated with a significant improvement in vascular function, with larger benefits seen at higher nitrate doses.⁶

In a small pilot study of healthy older adults, beetroot juice improved flow-mediated dilation within two weeks, and the improvement held at four weeks.⁷ Even a single dose of a beetroot-based gel given to elderly people with cardiovascular risk factors produced a notable jump in endothelial function alongside large increases in urinary nitrite and nitrate, confirming that the dietary nitrate was being converted and used.⁸ These vascular benefits are distinct from the blood pressure number on a cuff reading; they reflect the health and responsiveness of the blood vessel lining itself.

Exercise Performance and Oxygen Efficiency

One of the more remarkable findings about dietary nitrate is that it reduces how much oxygen your muscles need to do the same amount of work. In an early and influential trial, beetroot juice supplementation reduced the oxygen cost of moderate-intensity cycling by about 19%, an effect the researchers described as having “important implications for our understanding of the factors that regulate mitochondrial respiration.”⁹ Participants also lasted longer during high-intensity exercise before reaching exhaustion.

This oxygen-sparing effect appears to be more pronounced in recreational athletes and less-trained individuals. A study comparing runners with different fitness levels found that beetroot juice reduced oxygen cost during submaximal running in low-fit participants but had no measurable effect in highly trained runners.¹⁰ Elite athletes, whose bodies are already highly efficient at using oxygen, seem to get less additional benefit. That said, beetroot juice still boosted peak and mean power output during short, explosive efforts in football players, suggesting it can help with high-intensity bursts even in trained athletes.¹¹

At the cellular level, one proposed mechanism involves improvements in how efficiently mitochondria convert oxygen into usable energy. After nitrate supplementation, muscle biopsies showed an improved ratio of ATP produced per unit of oxygen consumed, along with reduced expression of a protein involved in proton leakage across the mitochondrial membrane.¹² Separate research in muscle cells has confirmed that beetroot juice can trigger mitochondrial biogenesis and increase the proportion of oxygen consumption that is coupled to ATP production, rather than wasted as heat.¹³ The net result is that your muscles squeeze more work out of each breath.

What Happens When Oxygen Is Scarce

The dietary nitrate pathway becomes even more relevant under low-oxygen conditions. Unlike the enzyme-driven nitric oxide synthase pathway, which needs oxygen to function, the nitrate-nitrite-nitric oxide pathway is enhanced during hypoxia and acidosis.¹⁴ This makes it a kind of backup system for maintaining nitric oxide signaling when the primary route falters.

In practical terms, this means beets may be especially useful at altitude or during situations where tissue oxygen delivery is compromised. A study simulating hypoxic conditions found that nitrate supplementation reduced the metabolic disruption in working muscles and restored exercise tolerance to levels normally seen at sea level.¹⁵ During a military trekking expedition at high altitude, supplementation appeared to slow the decline in fitness that accompanies acclimatization and promoted faster heart rate recovery after submaximal exercise.¹⁶

The conversion of nitrite to nitric oxide in blood vessels and red blood cells is itself accelerated under acidic and low-oxygen conditions, involving enzymes that become more active precisely when the body needs vasodilation most.¹⁷ This makes the dietary nitrate pathway a genuinely complementary system rather than a redundant one.

Brain Blood Flow and Cognition

Because nitric oxide dilates blood vessels throughout the body, the brain is also a potential beneficiary. A review of human studies found that nitrate-rich beetroot can improve cerebral blood flow and vascular responsiveness, and that higher intakes of plant-derived nitrate are associated with reduced cognitive decline over time.¹⁸ In a controlled crossover study, a single dose of dietary nitrate modulated blood flow in the prefrontal cortex during mental tasks and improved performance on a demanding subtraction test.¹⁹

The evidence here is genuinely mixed, though. A systematic review and meta-analysis of randomized trials found that overall, nitrate and nitrite supplementation did not significantly modify cerebral blood flow or cognitive function when results were pooled together.²⁰ Individual trials sometimes show positive effects on specific tasks, but the aggregate picture is inconclusive. It is possible that benefits are real but subtle, showing up under particular conditions or in certain populations, while being too small to survive pooling across diverse study designs. The brain research is promising but far less settled than the blood pressure data.

Effects on Platelets and Blood Clotting

Nitric oxide is a natural brake on platelet activation, and beets appear to engage that brake. In a pair of crossover studies, both beetroot juice and potassium nitrate capsules raised circulating nitrite levels and dampened platelet aggregation in response to common activating signals. The effect was associated with higher levels of a signaling molecule called cGMP inside the platelets. Interestingly, this antiplatelet effect showed up in male volunteers but not in females, a sex difference the researchers flagged as needing further investigation.²¹

Beyond the nitrate-to-nitric-oxide route, betanin, the red pigment responsible for beets’ characteristic color, also appears to inhibit platelet aggregation through a separate mechanism involving suppression of certain signaling enzymes within the platelet itself.²² So beets may thin the blood modestly through at least two independent pathways. For most healthy people this is a non-issue, but anyone on blood thinners or antiplatelet medication should be aware that heavy beetroot consumption could add to the effect.

What About People With Existing Health Conditions?

Peripheral artery disease, where narrowed arteries reduce blood flow to the legs, is one condition where beet-derived nitrate has shown real functional improvement. A trial in patients with the condition found that a moderate dose of beetroot juice improved endothelial function in both large and small vessels, reduced systolic blood pressure, and increased maximal walking distance by about 93 meters.²³ A companion analysis showed that the microvascular improvements were correlated with how much further participants could walk pain-free.²⁴

The picture is less encouraging for type 2 diabetes. A trial giving people with diabetes about 7.5 mmol of nitrate daily for two weeks raised their plasma nitrite and nitrate levels as expected, but did not produce any measurable improvement in blood pressure, endothelial function, or insulin sensitivity.²⁵ The reasons are unclear. One possibility is that the oxidative stress and vascular damage in diabetes interfere with the downstream conversion of nitrite to active nitric oxide. Whatever the explanation, the blanket assumption that beets will help anyone with cardiovascular risk does not hold up.

Timing, Dosing, and Food Form

Plasma nitrate levels rise within an hour of drinking beetroot juice and tend to plateau around five hours, while nitrite, the more biologically active intermediate, peaks at roughly two to three hours and can remain elevated for at least six hours. Higher doses produce higher and more sustained nitrite levels in a dose-dependent pattern.²⁶ Most of the studies showing cardiovascular or exercise benefits use somewhere in the range of 5 to 8 mmol of nitrate, which translates to roughly 250 to 500 ml of beetroot juice depending on the product’s concentration.

How you prepare beets also matters. Beetroot juice retains the highest nitrate content compared to chips, powders, or cooked beetroot.²⁷ Boiling vegetables in water generally leaches some nitrate out, reducing the content modestly, while frying can actually concentrate it.²⁸ If you are eating beets primarily for the nitrate, juice or raw preparations deliver more per serving than heavily cooked ones. Concentrated beetroot “shots” sold as sports supplements are designed to standardize the dose.

Beets Are Not Just Nitrate

Focusing exclusively on the nitrate story misses other compounds in beets that have their own biological activity. Betalains, the pigments that make beets deep red and purple, are potent antioxidants and anti-inflammatory agents. Betanin, the most abundant betalain, works as a free-radical scavenger through hydrogen and electron donation, protects LDL particles from oxidation, and activates antioxidant gene transcription while simultaneously suppressing pro-inflammatory signaling pathways.²⁹ Broader reviews have documented cardioprotective, hepatoprotective, neuroprotective, and gut-protective effects of betalains in laboratory and animal studies.³⁰

Whether those effects translate into clinically meaningful benefits in humans eating normal amounts of beets is still being worked out, but the point stands that when someone eats a beet, they are getting a package of bioactive compounds, not just a nitrate pill wrapped in fiber. Leafy greens like rocket, spinach, and celery also contain high levels of nitrate and can serve the same nitrate-to-nitric-oxide function, but they lack the concentrated betalains that beets provide.³¹

Safety, Nitrosamines, and the Cancer Question

The longstanding concern about dietary nitrate is that it can form nitrosamines, a class of compounds with known carcinogenic potential, particularly in the stomach under acidic conditions or during food processing at high temperatures.³² This worry originated primarily from research on processed meats, where nitrate and nitrite are added as preservatives and combined with proteins in a way that promotes nitrosamine formation. Vegetable-derived nitrate behaves differently because it arrives alongside vitamin C, polyphenols, and other antioxidants that inhibit nitrosamine production. A meta-analysis of dietary nitrate and gastric cancer actually found that higher vegetable nitrate intake was associated with a protective effect, likely because the fiber, vitamin C, and antioxidants in the vegetables more than offset any nitrosamine risk.³³

The most common side effect of eating a lot of beets is beeturia, the appearance of red or pink urine and sometimes reddish stools. It affects roughly 14% of people and is harmless. Whether you experience it depends on how your gut processes the betalain pigment. Oxalic acid in beets helps preserve the pigment’s red color all the way to the colon, where it gets absorbed; in people who don’t develop beeturia, stomach acid and colonic bacteria decolorize the pigment before absorption.³⁴ The only practical concern is that beeturia can be mistaken for blood in the urine if you have forgotten about the beets you ate the day before.