Place · Level 3
Beetroot nitrate
绿叶菜/甜菜根的硝酸盐 · 硝酸盐→亚硝酸盐→NO 的第二条路 · 降压约 −4 mmHg (真实但温和) · 精英运动员获益更小 · 别用抗菌漱口水杀掉舌头上的细菌
Story path
Chapter 1
What it is
What it is
Vegetables like beetroot, spinach, arugula, and celery contain something called nitrate (nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens.₃⁻). Eaten in enough quantity, it nudges blood pressure down a little and makes the same-intensity endurance effort cost slightly less. The odd part: its first step doesn't happen in your blood vessels but on your tongue — a community of bacteria on the tongue's dorsum first reduce nitrate to nitrite, and the body then converts that, step by step, into the vessel-relaxing gas nitric oxide (NO).
Where it acts: the mouth (nitrate-reducing bacteria on the tongue) → blood → smooth muscle of the vessel wall.
One point worth untangling first: nitrate in vegetables and the nitrate/nitrite added as a preservative to cured meats (bacon, ham, sausage) are the same class of ion but sit in completely different contexts. Vegetable nitrate arrives alongside plenty of vitamin C, polyphenols, and other antioxidants, and travels the positive vasodilation / endothelium-protecting route; the health concern with cured meat comes mainly from nitrosamines formed when nitrite meets amines under high-heat cooking, plus the salt and fat. Same molecule, different companions, different outcome.
Why does the body 'outsource' this to bacteria? Because mammals have no enzyme that can reduce nitrate to nitrite. That step depends entirely on commensal bacteria in the mouth — a genuine division of labor between human and microbe (Lundberg 2008 review). Green leafy vegetables are the dominant dietary source of nitrate (EFSA 2008), which is one clean mechanism behind the old refrain that 'dark vegetables are good for your heart.'
Where it acts: the mouth (nitrate-reducing bacteria on the tongue) → blood → smooth muscle of the vessel wall.
One point worth untangling first: nitrate in vegetables and the nitrate/nitrite added as a preservative to cured meats (bacon, ham, sausage) are the same class of ion but sit in completely different contexts. Vegetable nitrate arrives alongside plenty of vitamin C, polyphenols, and other antioxidants, and travels the positive vasodilation / endothelium-protecting route; the health concern with cured meat comes mainly from nitrosamines formed when nitrite meets amines under high-heat cooking, plus the salt and fat. Same molecule, different companions, different outcome.
Why does the body 'outsource' this to bacteria? Because mammals have no enzyme that can reduce nitrate to nitrite. That step depends entirely on commensal bacteria in the mouth — a genuine division of labor between human and microbe (Lundberg 2008 review). Green leafy vegetables are the dominant dietary source of nitrate (EFSA 2008), which is one clean mechanism behind the old refrain that 'dark vegetables are good for your heart.'
Chapter 2
The nitrate–nitrite–NO pathway
The nitrate–nitrite–NO pathway
The body makes nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. by two routes; beetroot takes the second.
Route one (classic): L-arginine → NO. The endothelial enzyme eNOS makes NO on demand from arginine + oxygen. This is the route covered on the citrulline island, and it needs adequate oxygen to run smoothly.
Route two (beetroot): nitrate → nitrite → NO. This is an enterosalivary circulation:
1. Swallowed nitrate is absorbed from the small intestine into the blood
2. About 25% is actively scavenged back by the salivary glands, concentrated into saliva, and returned to the mouth
3. Reducing bacteria on the tongue turn nitrate into nitrite
4. Once swallowed, the acidic stomach and hypoxic tissues further reduce nitrite into NO
Here's the key difference: route two works better the more hypoxic and acidic the environment gets — exactly when the classic eNOS route is struggling, as in exercising muscle and ischemic tissue. So the two routes aren't redundant, they're complementary: one supplies NO under oxygen, the other steps in under hypoxia and low pH (Lundberg 2008; Jones 2018).
This also explains why beetroot and citrulline shouldn't just be stacked blindly: citrulline raises the arginine pool (feeding route one), while beetroot raises the nitrate–nitrite pool (feeding route two). Both converge on NO, but through different inlets and for different scenarios — filling both up doesn't add to 1 + 1 = 2.
Route one (classic): L-arginine → NO. The endothelial enzyme eNOS makes NO on demand from arginine + oxygen. This is the route covered on the citrulline island, and it needs adequate oxygen to run smoothly.
Route two (beetroot): nitrate → nitrite → NO. This is an enterosalivary circulation:
1. Swallowed nitrate is absorbed from the small intestine into the blood
2. About 25% is actively scavenged back by the salivary glands, concentrated into saliva, and returned to the mouth
3. Reducing bacteria on the tongue turn nitrate into nitrite
4. Once swallowed, the acidic stomach and hypoxic tissues further reduce nitrite into NO
Here's the key difference: route two works better the more hypoxic and acidic the environment gets — exactly when the classic eNOS route is struggling, as in exercising muscle and ischemic tissue. So the two routes aren't redundant, they're complementary: one supplies NO under oxygen, the other steps in under hypoxia and low pH (Lundberg 2008; Jones 2018).
This also explains why beetroot and citrulline shouldn't just be stacked blindly: citrulline raises the arginine pool (feeding route one), while beetroot raises the nitrate–nitrite pool (feeding route two). Both converge on NO, but through different inlets and for different scenarios — filling both up doesn't add to 1 + 1 = 2.
Chapter 3
The blood-pressure effect
The blood-pressure effect
Numbers first, feelings second.
Siervo 2013 (Journal of Nutrition) meta-analysis (16 trials, 254 people): supplementing inorganic nitrate / beetroot juice lowered systolic blood pressure by about 4.4 mmHg on average (95% CI −5.9 to −2.8, P < 0.001), while diastolic dropped only about 1.1 mmHg and did not reach significance (P = 0.06). And it was dose-related — more nitrate, a bit more drop.
How to read that 4.4 mmHg?
It's real. The mechanism is clean (nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. relaxes vessels) and it replicates reasonably well.But it's modest — roughly the magnitude a single blood-pressure drug at a starting dose might contribute, not something that replaces medication.The effect leans acute: measurable within a single dose or a few days; whether it holds long-term and translates into fewer cardiovascular events, the evidence hasn't reached that bar.
So the honest framing: beetroot is one small piece of the dietary puzzle — meaningful stacked on top of eating more vegetables, cutting salt, and regular exercise, not something to treat as a blood-pressure prescription. For people with normal blood pressure the drop is barely noticeable; for those running high and eating few vegetables, the value is a bit higher.
Siervo 2013 (Journal of Nutrition) meta-analysis (16 trials, 254 people): supplementing inorganic nitrate / beetroot juice lowered systolic blood pressure by about 4.4 mmHg on average (95% CI −5.9 to −2.8, P < 0.001), while diastolic dropped only about 1.1 mmHg and did not reach significance (P = 0.06). And it was dose-related — more nitrate, a bit more drop.
How to read that 4.4 mmHg?
It's real. The mechanism is clean (nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. relaxes vessels) and it replicates reasonably well.But it's modest — roughly the magnitude a single blood-pressure drug at a starting dose might contribute, not something that replaces medication.The effect leans acute: measurable within a single dose or a few days; whether it holds long-term and translates into fewer cardiovascular events, the evidence hasn't reached that bar.
So the honest framing: beetroot is one small piece of the dietary puzzle — meaningful stacked on top of eating more vegetables, cutting salt, and regular exercise, not something to treat as a blood-pressure prescription. For people with normal blood pressure the drop is barely noticeable; for those running high and eating few vegetables, the value is a bit higher.
Clinical caution
This section isn't medical advice — just flagging where to check with a clinician:Already on blood-pressure medication: beetroot's effect is additive and may push your pressure a little lower than usual. Usually fine, but if you're mid-way through adjusting doses, adding a few-mmHg-per-day variable complicates the doctor's read on the drug — worth mentioning.On nitrate drugs (nitroglycerin, isosorbide mononitrate, common for angina): these directly supply NO themselves. Dietary nitrate doses are far below the drug's, but pushing both ends of the NO pathway together warrants caution — ask first.Kidney impairment: nitrate/nitrite handling and excretion involve the kidney; pharmacokinetics differ in serious renal disease, so don't self-dose heavily.Infants: high-nitrate sources (some homemade vegetable purées, well water) carry a methemoglobinemia risk in young babies — a different context, unrelated to adult exercise use, but worth knowing.
One-line rule: eaten as food, beetroot is safe for the vast majority; the moment you're on any drug affecting blood pressure or nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens., treat it as a variable to disclose.
Chapter 4
Endurance performance
Endurance performance
Beetroot got famous in endurance circles by doing something counter-intuitive: making the same effort cost less oxygen.
Larsen 2007 (Acta Physiologica) (9 well-trained men): after nitrate, at the same submaximal cycling load, oxygen uptake fell from 2.98 to 2.82 L/min, and gross efficiency rose from 19.7% to 21.1% (P < 0.01). In exercise physiology this is a near-'impossible' number — efficiency is usually treated as a physiological constant, hard to shift by anything short of training.
Bailey 2009 (J Appl Physiol) (8 people): beetroot juice cut the oxygen cost of submaximal exercise by about 5% and extended time-to-exhaustion in high-intensity work by about 16%.
How big, and for whom, needs stating plainly:
Recreational, fitness enthusiasts, intermittent high-intensity events: most likely to see benefit, usually on efforts from seconds to a dozen-odd minutes.Elite endurance athletes (VO₂peak above roughly 65 mL/kg/min): the benefit shrinks markedly, sometimes to undetectable — likely because their endothelial nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. output and mitochondrial efficiency are already trained to a ceiling, leaving little for nitrate to add (Jones 2018).Long time-trials (> 15–40 min): evidence is more inconsistent.
McMahon 2017 (Sports Medicine) meta-analysis put it bluntly: nitrate more reliably improves exercise capacity (time-to-exhaustion, how long you last), while the evidence for time-trial performance (how fast you go) is much weaker. In other words, it's more about delaying collapse than directly making you faster — a real but limited aid, not a gearbox.
Larsen 2007 (Acta Physiologica) (9 well-trained men): after nitrate, at the same submaximal cycling load, oxygen uptake fell from 2.98 to 2.82 L/min, and gross efficiency rose from 19.7% to 21.1% (P < 0.01). In exercise physiology this is a near-'impossible' number — efficiency is usually treated as a physiological constant, hard to shift by anything short of training.
Bailey 2009 (J Appl Physiol) (8 people): beetroot juice cut the oxygen cost of submaximal exercise by about 5% and extended time-to-exhaustion in high-intensity work by about 16%.
How big, and for whom, needs stating plainly:
Recreational, fitness enthusiasts, intermittent high-intensity events: most likely to see benefit, usually on efforts from seconds to a dozen-odd minutes.Elite endurance athletes (VO₂peak above roughly 65 mL/kg/min): the benefit shrinks markedly, sometimes to undetectable — likely because their endothelial nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. output and mitochondrial efficiency are already trained to a ceiling, leaving little for nitrate to add (Jones 2018).Long time-trials (> 15–40 min): evidence is more inconsistent.
McMahon 2017 (Sports Medicine) meta-analysis put it bluntly: nitrate more reliably improves exercise capacity (time-to-exhaustion, how long you last), while the evidence for time-trial performance (how fast you go) is much weaker. In other words, it's more about delaying collapse than directly making you faster — a real but limited aid, not a gearbox.
Why it saves oxygen
Same work — why suddenly less oxygen? Jones 2018 (Annual Review of Nutrition) groups the leading explanations into two:1. More oxygen-efficient adenosine triphosphate: The cell's universal energy currency — almost everything that costs energy spends it. production: nitrate-derived nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. appears to let mitochondria make the same ATP while leaking less oxygen (reduced proton leak) — more energy per breath of oxygen.
2. Cheaper muscle contraction: NO improves calcium handling and blood-flow distribution in fast-twitch (type II) fibers. Type II fibers are precisely the hypoxia-prone, fatigue-prone ones — and where the nitrate–nitrite route most readily helps under low oxygen and low pH, explaining why the benefit concentrates in high-intensity, intermittent efforts.
Two honest caveats:
Point 1 (mitochondrial efficiency) has not replicated reliably in later work — some studies detect no mitochondrial-level change. So exactly why it saves oxygen is still unsettled: the efficiency gain is a real phenomenon, but the pathway details are still argued.One plausible reason elites benefit less: training has already optimized their type II fiber blood flow, mitochondria, and endothelial function close to the ceiling, leaving little headroom for nitrate to move.
So it's closer to the truth to picture beetroot as 'a little extra NO for a system that still has headroom' than as a universal performance amplifier.
Chapter 5
Don't kill the bacteria
Don't kill the bacteria
Remember the first step is bacteria on your tongue? That step has a counter-intuitive consequence: antibacterial mouthwash switches the whole effect off.
Kapil 2013 (Free Radical Biology and Medicine) (19 healthy people): daily 0.2% chlorhexidine antibacterial mouthwash for 7 days cut oral nitrate reduction by about 90%, dropped plasma nitrite by about 25%, and raised systolic/diastolic blood pressure by about 2–3.5 / 2 mmHg. The pressure change was measurable after a single rinse and persisted for the following 6 days.
The mechanism is blunt: you have no nitrate-reducing enzyme of your own — it's entirely the tongue bacteria's job; antibacterial mouthwash kills indiscriminately and shuts down that 'outsourced production line' too. So if you're trying to lower blood pressure or fuel exercise with beetroot while using germ-killing mouthwash daily, you're building with one hand and demolishing with the other. At minimum, don't rinse with antibacterial mouthwash around the time you take nitrate.
Two more common exaggerations to dismantle:
Beetroot is a superfood / detoxes / purifies the blood: the numbers are right there — about 4 mmHg of BP, about 5% oxygen saving. A real, modest effect, not 'super'. The nitrate pathway has nothing to do with 'detox' — that's a marketing word.More is better: Wylie 2013 measured the dose-response directly — performance benefit is near-saturated around 8.4 mmol of nitrate, and doubling again to 16.8 mmol brought no additional benefit. More isn't better, it's just more.
Beetroot's value lies precisely in being verifiably modest: clear mechanism, clear dose, clear ceiling. Hyping it as a miracle actually squanders its rare quality of being explainable.
Kapil 2013 (Free Radical Biology and Medicine) (19 healthy people): daily 0.2% chlorhexidine antibacterial mouthwash for 7 days cut oral nitrate reduction by about 90%, dropped plasma nitrite by about 25%, and raised systolic/diastolic blood pressure by about 2–3.5 / 2 mmHg. The pressure change was measurable after a single rinse and persisted for the following 6 days.
The mechanism is blunt: you have no nitrate-reducing enzyme of your own — it's entirely the tongue bacteria's job; antibacterial mouthwash kills indiscriminately and shuts down that 'outsourced production line' too. So if you're trying to lower blood pressure or fuel exercise with beetroot while using germ-killing mouthwash daily, you're building with one hand and demolishing with the other. At minimum, don't rinse with antibacterial mouthwash around the time you take nitrate.
Two more common exaggerations to dismantle:
Beetroot is a superfood / detoxes / purifies the blood: the numbers are right there — about 4 mmHg of BP, about 5% oxygen saving. A real, modest effect, not 'super'. The nitrate pathway has nothing to do with 'detox' — that's a marketing word.More is better: Wylie 2013 measured the dose-response directly — performance benefit is near-saturated around 8.4 mmol of nitrate, and doubling again to 16.8 mmol brought no additional benefit. More isn't better, it's just more.
Beetroot's value lies precisely in being verifiably modest: clear mechanism, clear dose, clear ceiling. Hyping it as a miracle actually squanders its rare quality of being explainable.
Chapter 6
Practical use
Practical use
Compressing the evidence above into usable rules:
Dose: about 5–8 mmol of nitrate, which works out to roughly 310–500 mg (1 mmol nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens.₃⁻ ≈ 62 mg). A concentrated beetroot shot is usually in this range (about 400 mg / 6.4 mmol).
Timing: plasma nitrite peaks 2–3 hours after ingestion (Wylie 2013), so for exercise, take it 2–3 hours before the race/session — not a last-minute swig at the start line.
Single vs continuous: a single dose produces a measurable acute effect; taking it for 3–6 days usually makes the effect more consistent.
Food or supplement: a beetroot shot is precisely dosed and convenient; but eating enough leafy greens daily (arugula, spinach, beet greens, lettuce) also raises the nitrate pool, and brings fiber and other nutrients along. For most people, vegetables first, concentrated juice second is the more sensible order.
Who it's worth trying for:
Recreational endurance / intermittent athletes wanting to spare some effort in submaximal work → a meaningful small boostPeople running high blood pressure and eating few vegetables → as part of a dietary adjustmentElite endurance athletes hoping to chase results with it → don't expect much, the benefit is likely undetectable
Two things not to forget: (1) don't kill the bacteria with antibacterial mouthwash; (2) it takes a different NO inlet than citrulline — complementary, but no need to stack both. Try each on its own before reaching for the whole bundle.
Disclaimer: this page is educational, not medical advice. Beetroot as food is safe for the vast majority, but if you take blood-pressure or nitrate medication, have kidney disease, or are pregnant/breastfeeding, check with a clinician before using it as a deliberate supplement.
Dose: about 5–8 mmol of nitrate, which works out to roughly 310–500 mg (1 mmol nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens.₃⁻ ≈ 62 mg). A concentrated beetroot shot is usually in this range (about 400 mg / 6.4 mmol).
Timing: plasma nitrite peaks 2–3 hours after ingestion (Wylie 2013), so for exercise, take it 2–3 hours before the race/session — not a last-minute swig at the start line.
Single vs continuous: a single dose produces a measurable acute effect; taking it for 3–6 days usually makes the effect more consistent.
Food or supplement: a beetroot shot is precisely dosed and convenient; but eating enough leafy greens daily (arugula, spinach, beet greens, lettuce) also raises the nitrate pool, and brings fiber and other nutrients along. For most people, vegetables first, concentrated juice second is the more sensible order.
Who it's worth trying for:
Recreational endurance / intermittent athletes wanting to spare some effort in submaximal work → a meaningful small boostPeople running high blood pressure and eating few vegetables → as part of a dietary adjustmentElite endurance athletes hoping to chase results with it → don't expect much, the benefit is likely undetectable
Two things not to forget: (1) don't kill the bacteria with antibacterial mouthwash; (2) it takes a different NO inlet than citrulline — complementary, but no need to stack both. Try each on its own before reaching for the whole bundle.
Disclaimer: this page is educational, not medical advice. Beetroot as food is safe for the vast majority, but if you take blood-pressure or nitrate medication, have kidney disease, or are pregnant/breastfeeding, check with a clinician before using it as a deliberate supplement.