Beetroot Nitrates and Blood Pressure — What Does the Meta-Analysis Show?

Beetroot juice and beets as a vegetable have, on the internet and in parts of nutrition advice, the reputation of an almost miraculous natural blood-pressure lowering remedy. This reputation didn't come out of nowhere — beets, like arugula, spinach, or lettuce, belong to a group of vegetables exceptionally rich in inorganic nitrates (NO3-), compounds the body can convert into nitric oxide, a molecule with strong vasodilating action. This is a real, physiologically described biochemical pathway, not just a folk belief.

The question, however, is how large this effect actually is in practice, in whom it works best, and whether the data behind this reputation actually justify treating beets as an intervention comparable to the lifestyle changes described in our entry on hypertension, such as sodium reduction or the DASH diet. In this article we rely on one specific meta-analysis, the first to systematically compile available clinical trials on this topic.

Inorganic nitrates from food (highest in beets, but also in green leafy vegetables) are absorbed in the digestive tract and enter the bloodstream, from where part of them is actively taken up by the salivary glands and secreted back into the mouth along with saliva. This is a key, counterintuitive element of this mechanism: the further conversion of nitrates doesn't happen in the intestines, but on the surface of the tongue.

Anaerobic bacteria naturally living on the back of the tongue reduce nitrates to nitrites (NO2-) through an anaerobic fermentation process. Once swallowed again, nitrites are then converted, in the acidic environment of the stomach and in body tissues, into nitric oxide (NO) — the same signaling molecule that dilates blood vessels by relaxing the smooth muscles of their walls, lowering vascular resistance and, as a result, blood pressure. This is a pathway independent of the classic route of NO synthesis from the amino acid L-arginine via the NOS enzyme, making it a separate, additional mechanism of vascular tone regulation.

All 16 studies had a crossover design, and the intervention periods were short — from a single dose observed after 2 hours to a maximum of 15 days of regular use. In other words: this is a meta-analysis of short-term, acute effects, not data from many months or years of supplementation as we know from, for example, statin or antihypertensive drug studies.

The meta-analysis authors themselves explicitly noted in their summary that these results need confirmation in long-term studies and in populations at elevated cardiovascular risk — the groups for which a blood-pressure-lowering intervention would have the greatest practical clinical significance. This is an honest caveat worth keeping in mind whenever extrapolating these results to everyday, long-term use.

A drop in systolic blood pressure of 4.4 mmHg sounds modest compared to the effects of some antihypertensive drugs, which can lower pressure by ten or more mmHg. For comparison, though, in population-level epidemiological studies, lowering average systolic blood pressure across a population by even a few mmHg is associated with a measurable reduction in the risk of stroke and coronary heart disease at the population level — so an effect of this magnitude isn't physiologically trivial, even if it won't replace pharmacological treatment for a single individual.

A statistically significant effect on systolic pressure alongside a lack of significance for diastolic pressure is, moreover, a common pattern in studies of vasodilating interventions — it's consistent with the mechanism of action of nitric oxide, which affects large arteries and pulse wave dynamics more strongly than it does peripheral vascular resistance, which corresponds more to the diastolic value.

Since the key, necessary step of the entire pathway is the reduction of nitrates to nitrites by anaerobic bacteria on the tongue, the logical consequence is that the composition and activity of a given person's oral microbiome can meaningfully affect how much nitric oxide is ultimately produced from the same dose of dietary nitrates. This is still an area of active research, but mechanistically it's a plausible explanation for why some people report a more pronounced effect from beets than others at seemingly the same dose.

For the same reason, observations appear in the literature that regular use of strongly antibacterial mouthwashes may weaken this pathway, since they eliminate the tongue bacteria responsible for reducing nitrates to nitrites. This is an interesting but still insufficiently quantified aspect of the topic — we don't currently have reliable, precise figures indicating exactly how much an antibacterial mouthwash reduces the hypotensive effect of nitrates in an average person, so we limit ourselves here to a general, honest statement of the direction of this relationship, without providing made-up percentage figures.

A second common myth concerns the mechanism itself: some messaging suggests that the "beet" as a vegetable itself has magical properties, when in reality it's a specific, measurable chemical compound — inorganic nitrates — also present in other vegetables, though less often at as high a concentration as in beets and beetroot juice.

The Siervo and colleagues meta-analysis is a solid, systematic summary of the crossover studies available at the time of its publication, and it shows a real, measurable effect of beetroot nitrates on systolic blood pressure. At the same time, an honest presentation of this topic requires noting that we're talking about short-term, acute effects from small studies, not evidence of durable, long-term blood pressure control comparable to pharmacotherapy or to the best-documented lifestyle changes.

We treat beets and beetroot juice as a sensible addition, grounded in a real physiological mechanism, to a diet supporting healthy blood pressure — not as a replacement for treatment. For people with diagnosed hypertension, the most important advice remains the same: consult a doctor, measure blood pressure regularly, and stick to the prescribed treatment, with dietary interventions of this kind as a supplement, not an alternative.