Celery, Dietary Nitrate, and Blood Pressure

Table of Contents

1. Why a Vegetable’s Nitrate Matters
2. The Nitrate–Nitrite–Nitric Oxide Pathway
3. How Much Nitrate Celery Actually Has
4. What the Human Trials Show
5. Celery Seed Extract Is Not Celery
6. Potassium, Sodium and the Rest of the Picture
7. The Mouthwash Problem
8. “Uncured” Bacon and the Celery-Powder Label
9. Is Dietary Nitrate Safe?
10. Practical: How to Actually Use This
11. Who Should Be Careful
12. Key Research Papers
13. Connections
14. Featured Videos

Why a Vegetable’s Nitrate Matters

Nitrate has an image problem. Most people first meet the word on a warning label about processed meat, and reasonably conclude it is something to avoid. So it is genuinely surprising to learn that the overwhelming majority of the nitrate in a normal diet — roughly four-fifths of it in most populations — comes from vegetables, and that this vegetable nitrate is one of the better-supported reasons why vegetable-rich diets lower blood pressure.

Plants take up nitrate from the soil as their nitrogen source. Leafy and stem vegetables grown fast in rich, well-watered ground accumulate a lot of it. Celery is exactly that kind of crop — a thirsty, heavily fertilised, fast-growing marsh plant — and it sits in the highest nitrate band of common vegetables, alongside rocket (arugula), spinach, lettuce, beetroot and arugula.

For decades this was treated purely as a contaminant question. Then, over the 2000s, a body of work led by Jon Lundberg, Eddie Weitzberg and others showed that the human body has a use for nitrate: it runs a recycling pathway that converts it back into nitric oxide, a signalling molecule the body otherwise has to make from the amino acid arginine. The framing shifted from “how little nitrate can we get away with” to “dietary nitrate appears to be part of how vegetables protect the cardiovascular system”. Nathan Hord and colleagues made the point bluntly in a widely cited 2009 paper: the vegetables with the best evidence for lowering blood pressure — the ones in the DASH dietary pattern — happen to be the nitrate-rich ones.

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The Nitrate–Nitrite–Nitric Oxide Pathway

The pathway has an odd, memorable feature: it runs through the bacteria on your tongue. Here is the sequence.

1. You eat nitrate. Celery, beetroot, rocket, spinach or lettuce delivers inorganic nitrate, which is absorbed rapidly in the small intestine and enters the bloodstream.
2. A quarter of it is sent back to your mouth. The salivary glands actively concentrate circulating nitrate and secrete it into saliva. This looks wasteful until you see the next step.
3. Mouth bacteria reduce nitrate to nitrite. Specialised bacteria living in the crypts on the back of the tongue carry out a chemical step human cells cannot: stripping an oxygen atom from nitrate to make nitrite. This is a genuine symbiosis — the bacteria get energy, you get a nitric-oxide precursor.
4. Stomach acid and tissues turn nitrite into nitric oxide. Swallowed nitrite meets the acid of the stomach and is partly converted to nitric oxide there; the rest is absorbed and can be reduced to nitric oxide in blood and tissue, particularly where oxygen is low and blood flow is most needed.
5. Nitric oxide relaxes blood vessels. It diffuses into the smooth muscle in the artery wall, triggers a signalling cascade, and the muscle relaxes. Wider vessels mean lower pressure. Nitric oxide also makes platelets less sticky and improves the health of the endothelium, the single-cell lining of every blood vessel.

This is not a fringe mechanism. It is the same chemistry as nitroglycerin, the angina drug that has been relaxing arteries since the nineteenth century, arrived at from the other end. What changed in the 2000s was the recognition that a plate of vegetables feeds the same pathway.

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How Much Nitrate Celery Actually Has

Celery is consistently classified in the top nitrate tier of vegetables by both food-composition surveys and European food-safety assessments. Precise numbers are unhelpful here, and it is worth understanding why: the nitrate content of a given bunch of celery can vary several-fold depending on factors nobody prints on the label.

• Fertiliser. Heavily nitrogen-fertilised crops accumulate more nitrate. This is the single biggest driver.
• Light. Plants use light-driven enzymes to convert nitrate into amino acids, so vegetables harvested after dull weather, or grown under glass in winter, carry more unconverted nitrate than the same crop grown in strong sun.
• Part of the plant. In celery, the nitrate concentrates in the stalk and the lower stem more than in the leaves.
• Variety and season. Ordinary cultivar and weather variation adds several-fold spread on top of everything else.

The practical version of all this: a normal serving of celery makes a real contribution to daily nitrate intake, a large glass of celery juice makes a much larger one, and neither is a precisely dosed intervention. If you want a reliable, measured nitrate dose, that is what concentrated beetroot juice shots were invented for. If you want a food that pushes daily nitrate intake up as part of an eating pattern, celery does that perfectly well — and so do several other vegetables you may enjoy more.

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What the Human Trials Show

There are two separate bodies of evidence here, and mixing them up is the commonest mistake made about celery and blood pressure.

Evidence for dietary nitrate in general is strong. Most of it was generated using beetroot juice, because it is a convenient, standardisable, very high-nitrate vehicle. The landmark acute study by Andrew Webb and colleagues in 2008 gave healthy volunteers a large single dose of beetroot juice and saw systolic blood pressure fall by roughly ten millimetres of mercury at its peak a few hours later, with the effect fading over the following day. A crucial control in that work: if volunteers spat out their saliva instead of swallowing it, the effect largely disappeared — direct confirmation of the tongue-bacteria step.

Vikas Kapil and colleagues then ran the important follow-up in 2015: four weeks of daily nitrate-rich beetroot juice in people with actual hypertension, against a nitrate-depleted placebo juice. Blood pressure fell by something on the order of eight millimetres of mercury systolic and stayed down for the duration, with improved endothelial function and arterial stiffness alongside. A meta-analysis by Mario Siervo and colleagues pooling the trials available in 2013 put the average systolic effect at roughly four millimetres of mercury. Four points does not sound dramatic, but at population scale a shift of that size in average blood pressure is associated with a meaningful reduction in stroke and heart disease.

Evidence for celery specifically is thinner, and it is mostly about the seed. A 2025 systematic review and meta-analysis by Liu and colleagues pooled nine randomised controlled trials with 511 participants in total and found statistically significant but modest reductions in both systolic and diastolic pressure. The authors were careful to flag the limitation that matters: the trials differed widely in dose, in preparation, and in which part of the plant was used. A 2024 narrative review by Alobaidi and Saleh reached the same conclusion — encouraging, mechanistically plausible, and still preliminary.

What is missing is the study you would most want: a large, long, well-controlled trial of eating celery, or drinking its juice, with blood pressure as the primary outcome. It has not been done. Everything above is either a nitrate trial using a different vegetable, or a celery trial using a concentrated extract.

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Celery Seed Extract Is Not Celery

The strongest single human result for celery comes from Mahdi Shayani Rad and colleagues, who ran a randomised, triple-blind, placebo-controlled crossover trial of a standardised celery seed extract in people with mild to moderate hypertension and reported significant reductions in both systolic and diastolic pressure, with a companion paper reporting the safety and biochemical findings from the same programme. That is a well-designed study and it deserves to be taken seriously.

It is also not a study of celery the vegetable, and the difference is not a technicality.

• Different plant part. Celery seed is the seed of the same species, and it concentrates the aromatic and pharmacologically active constituents — the phthalides and flavones described on the Flavones and Phthalides page — at levels the blanched stalk never reaches.
• Different mechanism. The seed-extract work is generally interpreted through the phthalide 3-n-butylphthalide, a vessel-relaxing compound, rather than through nitrate. Celery seed carries almost no nitrate; the stalk carries a lot. They are two different arguments that happen to involve the same species.
• Different dose. Standardised capsules deliver a measured amount of the active fraction. A stalk of celery delivers whatever that stalk happened to grow.

So when a headline says “celery lowers blood pressure”, the honest translation is usually “a concentrated celery seed extract capsule lowered blood pressure in a small trial”. Both facts are real; they simply do not support each other as directly as the headline implies. If you are considering a celery seed extract supplement, treat it as you would any pharmacologically active product: it is potent enough to matter, potent enough to interact with blood-pressure medication, and worth mentioning to whoever manages your prescriptions.

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Potassium, Sodium and the Rest of the Picture

Nitrate is not the only blood-pressure-relevant thing in a stalk of celery.

Potassium is the big one, and its evidence base is stronger than nitrate’s. Potassium helps the kidney excrete sodium, relaxes vascular smooth muscle and blunts the pressure response to a salty diet. A large systematic review and meta-analysis by Nancy Aburto and colleagues, published in the BMJ in 2013 and used in the World Health Organization’s guidance, found that increasing potassium intake lowered blood pressure in adults with hypertension by roughly three to four millimetres of mercury systolic, with an associated reduction in stroke risk. Celery is a respectable but not spectacular potassium source; the point is that it contributes to a pattern. See Potassium for the full picture.

Sodium deserves an honest mention because celery is unusual among vegetables in containing a noticeable amount of it naturally — it is a salt-marsh plant, after all. In ordinary dietary quantities this is irrelevant next to the sodium in bread, cheese and processed food, and it is not a reason to avoid celery. It is worth knowing only if you are following a genuinely strict sodium restriction and drinking large volumes of celery juice, where the amounts stop being trivial. See Sodium.

Fibre and water matter indirectly. Celery is about ninety-five percent water and carries a stiff, visible fibre, which is why it is filling for so few calories. Weight is one of the strongest modifiable influences on blood pressure, and a food that helps you eat well without eating much is doing useful work even if none of its molecules touch a blood vessel.

The flavones apigenin and luteolin have vasorelaxant and anti-inflammatory activity in laboratory models. That work is real but preclinical, and it is covered honestly on its own page.

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The Mouthwash Problem

This is the most practically useful and least known consequence of the whole pathway.

Because the nitrate-to-nitrite step is performed by bacteria on the tongue, anything that kills those bacteria breaks the chain. Studies using antibacterial mouthwash have repeatedly shown that it reduces salivary nitrite and blunts the blood-pressure-lowering effect of dietary nitrate. Rinsing with a strong antiseptic mouthwash can undo, in thirty seconds, the benefit of the vegetables you ate at lunch.

This is not an argument for poor oral hygiene — gum disease is itself associated with cardiovascular risk, and brushing and flossing are not the problem. The step under discussion is specifically antiseptic mouthwash used routinely, which is not necessary for most people. The oral nitrate-reducing bacteria are now being studied in their own right as potential probiotics for blood-pressure regulation, which gives some sense of how seriously the field takes them.

Two smaller corollaries follow from the same mechanism. Swallowing rather than spitting matters, which is why the effect is blunted in the spit-out control arms of these studies. And proton-pump inhibitors, which suppress stomach acid, may reduce the acid-dependent conversion of nitrite to nitric oxide in the stomach — a plausible interaction that has not been resolved in outcome trials.

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“Uncured” Bacon and the Celery-Powder Label

If you have ever bought bacon, hot dogs or deli meat labelled “uncured — no nitrates or nitrites added” and then read the ingredients and found cultured celery powder, you have met one of the more misleading pieces of food labelling in the shop. It is worth understanding, because it is the direct commercial application of everything above.

Meat curing needs nitrite. Nitrite is what gives cured meat its pink colour, its characteristic flavour, and — most importantly — its protection against Clostridium botulinum. Conventional curing adds sodium nitrite directly. The alternative process takes a high-nitrate vegetable concentrate — almost always celery powder or celery juice concentrate — and ferments it with a nitrate-reducing bacterial culture, which converts the vegetable nitrate into nitrite. That nitrite then cures the meat.

Joseph Sebranek and James Bacus laid the chemistry out plainly in a 2007 review, and it has been restated repeatedly since: the curing agent is the same molecule either way. Nitrite from celery and nitrite from a jar are chemically identical, they cure meat by the same reaction, and the finished products can contain comparable amounts. In some cases the celery-cured product contains more, because the vegetable route is harder to dose precisely. The “uncured” label exists because of a regulatory definition that reserves the word “cured” for directly added nitrite, not because anything about the product is meaningfully different.

What this does and does not mean. It does not mean celery is dangerous — the concern with processed meat is about nitrite reacting with amines in meat under heat to form nitrosamines, a reaction that does not happen in a stalk of celery, which comes packaged with vitamin C and polyphenols that actively block nitrosation. That asymmetry — nitrate in vegetables looking protective, nitrite in processed meat looking harmful — is the central puzzle of the field, and it is best explained by the company each keeps rather than by the molecule itself. What the label does mean is that if you are avoiding cured meat, an “uncured” version is not the way to do it. See Nitrates and Nitrites.

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Is Dietary Nitrate Safe?

The short answer for vegetables is yes, and the long answer is worth having because the question is asked constantly.

Nitrate itself is largely inert. The concerns attach to nitrite, and there are two of them. The first is methaemoglobinaemia — the “blue baby” syndrome — which is a genuine, serious risk in infants under about six months, primarily from nitrate-contaminated well water, and the reason spinach- and celery-heavy purees are not recommended for very young babies. The second is nitrosamine formation, which requires nitrite plus amines plus favourable conditions, and which is a meat-processing problem rather than a vegetable problem.

European food-safety assessment of nitrate in vegetables concluded that the benefits of vegetable consumption outweigh the risks associated with their nitrate content, and reviews of the controversy by Jeffrey Sindelar, Andrew Milkowski and colleagues have made the same argument at length. No health authority recommends reducing vegetable intake to lower nitrate exposure. The practical reading is simple: eat the vegetables, including the nitrate-rich ones, and treat processed meat as its own separate question.

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Practical: How to Actually Use This

Concrete things that follow from the evidence, rather than from wishful thinking:

• Eat nitrate-rich vegetables most days, and vary them. Celery, rocket, spinach, lettuce, beetroot, chard, and celery’s relatives. The pathway responds to a habit, not to a single heroic serving; the acute effect of any one dose fades within about a day.
• Do not boil the nitrate away and pour it down the sink. Nitrate is water-soluble and leaches into cooking water. Raw celery, or celery in a soup or stew where you eat the liquid, keeps it; boiled-and-drained celery loses a good deal of it.
• Keep the leaves. The leafy tops are the most nutrient-dense part of the plant and most people throw them out. Chop them into salads, soups, stocks and grain bowls.
• Ease off routine antiseptic mouthwash unless you have been told to use it. Brush and floss instead.
• Eat it rather than juice it, if the choice is free. Whole celery gives you the same nitrate plus the fibre and the fullness. Blending keeps the pulp; juicing throws it away.
• Pair it with the rest of the pattern. Nitrate-rich vegetables sit inside a broader picture — more potassium, less added salt, more whole plant food, weight and alcohol under control, and regular movement — that together does far more than any one component. Brown rice, beans, oily fish, olive oil, nuts and a wide range of vegetables is the shape of it.
• Do not stop your medication. If you take blood-pressure medication, none of this is a substitute for it. It is a reasonable addition, and it is worth telling your prescriber if your readings start coming down, because doses sometimes need adjusting downwards — which is a good problem to have.

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Who Should Be Careful

• Anyone on blood-pressure medication who adds a concentrated celery seed extract supplement — the combined effect can overshoot. The vegetable is not the issue; the capsules are pharmacologically active.
• People with advanced kidney disease or on potassium-restricted diets, for whom large volumes of any vegetable juice are a genuine potassium load worth discussing with the renal team.
• Infants under six months should not be given celery or spinach purees or juices, because of the methaemoglobinaemia risk described above.
• Anyone with a celery allergy. Celery is a recognised cause of anaphylaxis and is a labelled allergen across the European Union. If that is you, none of this page applies — see Allergy and Photosensitivity.
• People taking warfarin should keep their vitamin K intake steady rather than swinging between none and a lot; celery contributes some. Consistency is what matters, not avoidance. See Vitamin K.

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Key Research Papers

Author names, titles and journals are plain text; only the DOI is a link, and each opens in a new tab. Where a claim in this article is qualitative rather than numerical, that is deliberate — the underlying trials vary enough that a single number would misrepresent them.

1. Lundberg JO, Weitzberg E, Gladwin MT. The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics. Nature Reviews Drug Discovery. 2008;7(2):156-167. — doi:10.1038/nrd2466 — the review that established the pathway described in this article.
2. Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. The American Journal of Clinical Nutrition. 2009;90(1):1-10. — doi:10.3945/ajcn.2008.27131 — ranks vegetables by nitrate content and connects them to the DASH pattern.
3. Webb AJ, Patel N, Loukogeorgakis S, et al. Acute blood pressure lowering, vasoprotective, and antiplatelet properties of dietary nitrate via bioconversion to nitrite. Hypertension. 2008;51(3):784-790. — doi:10.1161/hypertensionaha.107.103523 — the acute beetroot-juice study, including the spit-out control that proved the tongue-bacteria step.
4. Kapil V, Khambata RS, Robertson A, et al. Dietary nitrate provides sustained blood pressure lowering in hypertensive patients. Hypertension. 2015;65(2):320-327. — doi:10.1161/hypertensionaha.114.04675 — four weeks of daily nitrate in people with actual hypertension.
5. Siervo M, Lara J, Ogbonmwan I, Mathers JC. Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis. The Journal of Nutrition. 2013;143(6):818-826. — doi:10.3945/jn.112.170233
6. Liu D, Zhao H, Xu H, Hu J. Effects of celery (Apium graveolens) on blood pressure, glycemic and lipid profile in adults: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Nutrition. 2025;12:1597680. — doi:10.3389/fnut.2025.1597680 — nine trials, 511 participants; modest significant reductions with wide heterogeneity.
7. Shayani Rad M, Moohebati M, Mohajeri SA. Effect of celery (Apium graveolens) seed extract on hypertension: a randomized, triple-blind, placebo-controlled, cross-over clinical trial. Phytotherapy Research. 2022;36(7):2889-2907. — doi:10.1002/ptr.7469
8. Shayani Rad M, Moohebati M, MohammadEbrahimi S, et al. Safety evaluation and biochemical efficacy of celery seed extract (Apium graveolens) capsules in hypertensive patients: a randomized, triple-blind, placebo-controlled, cross-over clinical trial. Inflammopharmacology. 2022;30(5):1669-1684. — doi:10.1007/s10787-022-00986-0
9. Alobaidi S, Saleh E. Antihypertensive property of celery: a narrative review on current knowledge. International Journal of Food Science. 2024;2024:9792556. — doi:10.1155/2024/9792556
10. Moghadam MH, Imenshahidi M, Mohajeri SA. Antihypertensive effect of celery seed on rat blood pressure in chronic administration. Journal of Medicinal Food. 2013;16(6):558-563. — doi:10.1089/jmf.2012.2664
11. Tashakori-Sabzevar F, Razavi BM, Imenshahidi M, et al. Evaluation of mechanism for antihypertensive and vasorelaxant effects of hexanic and hydroalcoholic extracts of celery seed in normotensive and hypertensive rats. Revista Brasileira de Farmacognosia. 2016;26(5):619-626. — doi:10.1016/j.bjp.2016.05.012
12. Illes J, Rodrigues J. The influence of celery (Apium graveolens) juice on hypertension. In: Reference Series in Phytochemistry. 2024:501-523. — doi:10.1007/978-3-031-38663-3_72
13. Aburto NJ, Hanson S, Gutierrez H, Hooper L, Elliott P, Cappuccio FP. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ. 2013;346:f1378. — doi:10.1136/bmj.f1378
14. Sebranek JG, Bacus JN. Cured meat products without direct addition of nitrate or nitrite: what are the issues? Meat Science. 2007;77(1):136-147. — doi:10.1016/j.meatsci.2007.03.025 — the chemistry behind “uncured” labelling.
15. Sindelar JJ, Milkowski AL. Human safety controversies surrounding nitrate and nitrite in the diet. Nitric Oxide. 2012;26(4):259-266. — doi:10.1016/j.niox.2012.03.011
16. Bedale W, Sindelar JJ, Milkowski AL. Dietary nitrate and nitrite: benefits, risks, and evolving perceptions. Meat Science. 2016;120:85-92. — doi:10.1016/j.meatsci.2016.03.009
17. EFSA Panel on Contaminants in the Food Chain. Nitrate in vegetables — scientific opinion. EFSA Journal. 2008;6(6):689. — doi:10.2903/j.efsa.2008.689 — concludes the benefits of vegetable consumption outweigh the nitrate risk.
18. Chai X, Liu L, Chen F. Oral nitrate-reducing bacteria as potential probiotics for blood pressure homeostasis. Frontiers in Cardiovascular Medicine. 2024;11:1337281. — doi:10.3389/fcvm.2024.1337281 — the mouthwash problem, taken seriously.

Live PubMed Searches

1. PubMed: dietary nitrate and blood pressure, randomised trials
2. PubMed: Apium graveolens and hypertension
3. PubMed: mouthwash, salivary nitrite and blood pressure
4. PubMed: celery powder and alternative meat curing
5. PubMed: vegetable nitrate content and its variability

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Connections

• All Food
• Celery
• Celery Benefits Deep Dive
• Celery: History and Origins
• Apigenin, Luteolin and the Celery Phthalides
• The Celery Juice Claims
• Beets — the vegetable most of the nitrate research was done with
• Arugula
• Spinach
• Garlic
• Potassium
• Sodium
• Vitamin K
• Hypertension
• Nitrates and Nitrites
• Celery Juice

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