Your Gut Bacteria Turn Beetroot and Spinach Into a Blood Pressure Molecule
I get asked some version of the same question constantly. Why do leafy greens and beetroot keep showing up in blood pressure research. There has been a partial answer for years, a pathway where dietary nitrate becomes nitric oxide in the body. This new paper describes a different route, and the detail that makes it stick is almost embarrassingly simple: the vegetable is not the active ingredient. Your gut bacteria are the factory.
- Karolinska Institutet researchers report in Cell that gut bacteria combine dietary nitrate, from beetroot, spinach and rocket, with plant iron, from beans, whole grains and greens, into a molecule called a dinitrosyl iron complex, or DNIC, which the body absorbs and sends to the liver and kidneys.
- Germ free mice, raised with no gut bacteria at all, made none of the molecule, even when fed the same nitrate and iron as normal mice. No bacteria, no molecule.
- Raising DNIC levels improved blood pressure, blood sugar control and liver fat in an animal model of cardiometabolic disease.
- Every health result here is from animals. The human part of the study only confirmed the molecule exists in human tissue, not that it does anything beneficial in people.
What the researchers actually found
Beetroot, one of the two named dietary nitrate sources this study describes, shown as harvested rather than processed or packaged.
Nick SaltmarshCC BY 2.0
Illustrative: beetroot in general, not a specific vegetable sample analyzed in this study.
Karolinska Institutet researchers, working with University Medical Centre Hamburg Eppendorf and Johannes Gutenberg University Medical Centre Mainz, report that gut bacteria take two things you get from vegetables, dietary nitrate from beetroot, spinach and rocket, and non haem iron from beans, whole grains and greens, and build them into a molecule called a dinitrosyl iron complex. This DNIC is stable enough to be absorbed and carried through the body, reaching tissue, chiefly the liver and kidneys. The work spans mice, cells, isolated bacteria and human samples, and identified DNIC in multiple human tissues using advanced analytical methods.
The control that makes the mechanism claim stick
The detail that convinces me this is real rather than just a plausible story is the germ free mouse result. Germ free mice, raised with no gut bacteria at all, produced none of the molecule, even when fed the identical nitrate and iron as ordinary mice. No bacteria, no DNIC, full stop. Raising DNIC levels, either by feeding nitrate plus iron together or by giving the synthetic molecule directly, improved blood pressure, vascular function, blood sugar control and liver fat in an animal model of cardiometabolic disease. The funding here is worth naming on a beat where most microbiome findings arrive attached to a supplement company: public and philanthropic sources only, and the authors state they have no conflicts of interest.
No bacteria, no DNIC, full stop.
Honest caveat
This is preclinical. Every health outcome, blood pressure, blood sugar control, liver fat and vascular function, comes from an animal model, not from people. The human component of this research is sample analysis confirming DNIC exists in human tissue, not a trial showing DNIC does anything beneficial in humans, and the researchers say so themselves, naming the next step as developing methods to measure DNIC in people. No dose, no food quantity and no eat this many grams of spinach recommendation can honestly be drawn from this paper. It is also a single study, not yet replicated by an independent group, though it does span multiple institutions.
What this means for you
There is no actionable dose here, and I want to be direct about that rather than stretch a mouse finding into advice. What this paper does offer is a genuinely useful mental model: the benefit people associate with nitrate rich vegetables may depend on pairing them with a plant iron source, beans, whole grains, leafy greens, rather than isolating the nitrate alone. That also quietly complicates the case for a nitrate only beetroot shot or powder, since it supplies only half of what this mechanism appears to need. Whether that pairing matters in a living, breathing person is exactly what has not been tested yet.
Primary sources
- Kleschyov AL, Shimari M, Boeder AM, et al. "Gut microbiota generate dinitrosyl iron complexes with cardiometabolic benefits." Cell, published online August 19, 2026.
- Karolinska Institutet institutional release, "Gut bacteria convert dietary nitrate and iron into protective molecules," published August 19, 2026.
Common questions
Should I eat more beetroot and spinach for blood pressure?
This finding does not tell you that. Every blood pressure, blood sugar and liver fat result in this study came from animals, not people. The human part of the research only confirmed the molecule exists in human tissue, not that eating more of these vegetables changes any health outcome in a person. No dose or serving size can honestly be recommended from this paper.
Would a nitrate supplement or beetroot shot do the same thing?
Based on this mechanism, probably not by itself. The molecule these researchers describe is built from dietary nitrate and plant iron together, not nitrate alone. An isolated nitrate shot or powder skips half of what the gut bacteria appear to need, which is a real reason for skepticism about products that supply only the nitrate half of the pairing.
What does it mean that germ free mice cannot make the molecule at all?
Germ free mice are raised with no gut bacteria at all. Researchers found these mice produced none of the molecule in question, even when fed the same nitrate and iron as normal mice. That is what tells them gut bacteria are required to build it, rather than the vegetable itself containing the active ingredient.
Stay Curious.
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