Vietnamese Coriander: The Bone and Memory Clinical Trials
This page exists because of a genuine surprise in researching this herb: rau răm does have real human clinical-trial data behind it — two double-blind, placebo-controlled randomized trials, the only human trials this plant has ever had for any claim. That is a real correction to what this site previously said. It comes with an equally important qualification the headline fact does not carry on its own: neither trial tested rau răm by itself. Both tested a proprietary congee built from rau răm blended with mulberry leaf, and untangling what that does and does not tell you about rau răm specifically is the entire subject of this page.
Table of Contents
- The Headline Fact: Two Real Human Trials Exist
- One Laboratory, One Formula, Two Endpoints
- The Precursor: What the 2014 Rat Study Showed
- Trial One: Bone-Turnover Markers in Menopausal Women (2018)
- Trial Two: Memory and Cognition (2022)
- The 2026 Correction: What Is and Is Not Known
- Why "Combined Extract" Is Not "Rau Răm"
- What Mulberry Brings to the Formula on Its Own
- What Rau Răm Itself Might Be Contributing — and Why This Page Will Not Guess at a Dose
- The Three-Verdict Framework, Applied to a Genuinely Unusual Case
- What This Does and Does Not Support
- Key Research Papers
- Connections
The Headline Fact: Two Real Human Trials Exist
The main rau răm page used to state flatly that no human trials of any kind existed for this plant. That statement has been corrected on this page's evidence, in four places on the main page, because it was not accurate. A live search of the biomedical literature turns up exactly two randomized, double-blind, placebo-controlled human trials that include Polygonum odoratum as a study ingredient — one from 2018, one from 2022, both from the same Thai research group at Khon Kaen University.
This matters, and it is worth being honest about why it was missed the first time: neither trial's title leads with "Vietnamese coriander" or "rau răm." One is titled around "polyphenol-rich herbal congee" and bone turnover; the other around "quercetin-enriched culinary herbs-derived functional ingredients" and memory. A search built only around the plant's own common or scientific names, without also searching combination-product and formula terminology, would miss both — which is itself a reminder that "no human trials" claims deserve periodic re-checking with broader search terms, not just repetition.
One Laboratory, One Formula, Two Endpoints
All three papers behind this page — the 2014 rat study and the two human trials — share overlapping authorship centred on Jintanaporn Wattanathorn's group at the Khon Kaen University Faculty of Medicine and its Integrative Complementary Alternative Medicine Research and Development Center, working with the same collaborator, Wichai Somboonporn, from the university's Department of Obstetrics and Gynaecology. All three use the identical intervention: a combined extract of mulberry (Morus alba) leaf and rau răm (Polygonum odoratum) leaf, delivered as an herbal congee (a rice-porridge-based functional food, a genuinely Thai delivery format for a nutraceutical). This is a coherent, deliberate research program — rat safety and mechanism work first, then two separate human trials testing two different hypothesised benefits of the same fixed formula — not three unrelated studies that happen to share an ingredient.
The Precursor: What the 2014 Rat Study Showed
Before either human trial, the same group tested the combined extract in ovariectomized rats — a standard animal model of post-menopausal estrogen loss and bone density decline, since surgical removal of the ovaries removes the hormone that normally restrains bone resorption. Rats received the combined extract orally at 5, 150 or 300 mg/kg body weight for three months. The combined extract decreased bone oxidative-stress markers and osteoclast density (the cells that break down bone) while increasing osteoblast density (the cells that build it) and cortical bone thickness, alongside elevated serum osteocalcin, alkaline phosphatase and calcium — a coherent pattern consistent with reduced bone resorption and increased bone formation. The authors' own conclusion was appropriately cautious, explicitly stating that "further studies concerning chronic toxicity and the underlying mechanism are required" before drawing larger conclusions.
This is the standard, responsible order of operations for developing a botanical product — animal safety and mechanism data before human dosing — and it is worth noting because it means the two human trials that followed were not a leap from folklore straight to a clinical trial. They followed a real, if modest, preclinical foundation. That foundation, however, was already about the combined extract, not rau răm alone; the species-attribution question described later on this page starts here, not at the human-trial stage.
Trial One: Bone-Turnover Markers in Menopausal Women (2018)
Published in Oxidative Medicine and Cellular Longevity in 2018, this trial enrolled 45 perimenopausal and menopausal women, randomized into a placebo group and two active-dose groups (50 mg/day and 1,500 mg/day of the combined mulberry–rau răm congee extract) for eight weeks. The primary outcomes were serum bone-turnover markers: calcium, alkaline phosphatase, osteocalcin (a marker of bone formation) and beta-CTX (a marker of bone resorption), alongside routine haematology, blood chemistry safety monitoring, and total serum phenolic content as a marker of compliance and absorption.
The higher-dose (1,500 mg/day) group showed statistically significant increases in serum alkaline phosphatase, osteocalcin and total phenolic content, and a decrease in CTX — the same directional pattern (more formation, less resorption) seen in the preceding rat study. Clinical safety assessment found no toxicity or adverse effects over the eight-week period. The authors' conclusion is carefully scoped: the congee is "the potential functional food that can decrease the risk of osteoporosis" — a hedged, hypothesis-generating statement about a functional food, not a claim of treatment or prevention of diagnosed osteoporosis, and appropriately so for a single 45-person, eight-week trial measuring biochemical markers rather than actual fracture risk or bone density by DXA scan.
Trial Two: Memory and Cognition (2022)
The same group returned to the identical combined extract four years later for a different question, published in Foods in 2022. Forty-five participants were randomized to placebo or the same 50 mg/day or 1,500 mg/day doses, again for eight weeks. This time the endpoints were cognitive: working memory assessed by computerized battery testing and event-related potentials (N100 and P300 — electroencephalogram measures of attention and stimulus-processing speed), plus blood-based enzyme activity for acetylcholinesterase (AChE) and monoamine oxidase types A and B (MAO-A, MAO-B).
The 1,500 mg/day group showed reduced latency and increased amplitude on the N100 and P300 measures (consistent with faster, more robust attentional processing), improved working-memory task performance, and suppressed activity of AChE, MAO-A and MAO-B. The mechanistic logic connecting those enzyme changes to memory is well established in pharmacology generally — acetylcholinesterase inhibition is the mechanism of every currently approved Alzheimer's drug in the donepezil/rivastigmine/galantamine class, because blocking the enzyme that breaks down acetylcholine leaves more of that memory-relevant neurotransmitter available; MAO inhibition is a much older mechanism from early antidepressant pharmacology, relevant here because monoamine levels also affect cognitive and mood function. The authors reasonably propose this enzyme-suppression pathway as the likely mechanism behind the observed cognitive changes, which is a coherent, literature-consistent hypothesis rather than a stretch — a review of essential oils and acetylcholinesterase inhibition confirms this is a real, actively studied mechanism class for plant-derived compounds generally, not an idea invented for this one formula.
The 2026 Correction: What Is and Is Not Known
In March 2026, twelve years after its original publication, the underlying 2014 rat study received a formal correction notice from its journal. This deserves to be reported honestly and without embellishment in either direction: the correction notice available through PubMed states only that it "corrects the article" and provides no public detail about what was changed or why. This page will not speculate about the reason — inventing an explanation would be exactly the kind of unsupported number this site's evidence standard exists to prevent.
What can be said factually: Oxidative Medicine and Cellular Longevity, the journal that published both the 2014 rat study and the 2018 human bone trial, is a Hindawi-family title that has been the subject of large-scale, publicly documented post-publication corrections and retractions across its back catalogue since 2023, following broader concerns about compromised peer review at a number of Hindawi journals during that period. That context does not mean this specific paper's science is wrong — a corrigendum is a formal correction, not a retraction, and the paper remains indexed and citable — but it is a legitimate reason for a reader to weigh this particular trial's findings with somewhat more caution than a paper from a journal without that recent history, and it is exactly the kind of caveat that belongs beside the citation rather than left for a reader to discover separately.
Why "Combined Extract" Is Not "Rau Răm"
Here is the central, unavoidable limitation of both trials, and it is worth stating in the plainest possible terms: at no point in either human trial, or in the rat study before them, was rau răm ever tested alone. Every dose in every study was a fixed combination with mulberry leaf, and none of the three papers reports the individual ratio of the two ingredients within that combination or attempts to isolate which herb contributed which part of the measured effect.
This is a textbook example of what this site's evidence-checking convention calls formula substitution: crediting a single named herb with the results of a multi-ingredient product, when the product's own stated design intent was combination. It is the same structural problem as Triphala results being cited for one of its three component fruits alone, or a multi-herb energy formula's results being credited to a single ingredient on the label. The difference here is that the formula substitution is easy to miss, because both trial titles genuinely do name "Polygonum odoratum" as a study ingredient — it is not a hidden or mislabeled formula, just an inseparable one.
The honest conclusion is not "these trials are worthless" — they are real, reasonably well-designed, safety-monitored human RCTs, which is more than almost anything else on this plant's entire literature file. The honest conclusion is narrower: they are evidence that this specific two-herb congee, at this specific dose, may support bone-turnover markers and working memory over eight weeks. They are not evidence, on their own, that rau răm alone does either of those things, at any dose, for any duration.
What Mulberry Brings to the Formula on Its Own
Mulberry (Morus alba) leaf has its own separate, more developed evidence base for bone metabolism, entirely independent of rau răm. A 2026 study in the Journal of Ethnopharmacology found mulberry polyphenols promoted bone formation and reduced bone loss through dual regulation of bone metabolism — tested as mulberry alone, in its own right, not as part of this specific congee. Mulberry leaf is also independently well known in the broader phytochemistry literature as a rich source of the polyphenol 1-deoxynojirimycin and various flavonoids studied for blood-sugar and metabolic effects.
This matters directly to how the Wattanathorn group's own trials should be read: mulberry is not a neutral inert carrier added to bulk out a rau răm product. It is itself a botanical with independently documented, plausible bone-relevant activity. That raises a genuinely open question this page cannot answer, and will not pretend to: how much of the combined extract's measured effect in these two trials came from the mulberry half, how much from the rau răm half, and how much required both together? No study has isolated that question for this formula, and until one does, the honest position is that the answer is unknown — not that it defaults to rau răm.
What Rau Răm Itself Might Be Contributing — and Why This Page Will Not Guess at a Dose
It is reasonable to ask whether rau răm's own documented chemistry gives any plausible reason to expect it contributes something to this formula, rather than riding along inertly on mulberry's effect. The anti-inflammatory research on this plant independently confirms rau răm leaf extract is genuinely rich in quercetin, along with catechin, gallic acid and epicatechin gallate — and the 2022 memory trial's own title specifically describes the intervention as "quercetin-enriched," which is consistent with rau răm being a deliberate, chosen source of that compound in the formula rather than an incidental inclusion.
That is a real, chemically grounded reason to think rau răm was included on purpose rather than as filler. It is not, and this page will not pretend it is, a basis for estimating what dose of rau răm alone would reproduce any part of the trials' results. As on the anti-aphrodisiac page's mechanism section, the same restraint applies here: no study reports the mulberry-to-rau-răm ratio in the tested congee, no study reports how much quercetin came from which ingredient, and no pharmacokinetic data exists for rau răm's compounds taken alone. Constructing a "how much rau răm you'd need" figure from these trials would require inventing at least two numbers this page does not have. It refuses to.
The Three-Verdict Framework, Applied to a Genuinely Unusual Case
This site's evidence-grading convention distinguishes three outcomes for a botanical claim: absent (never adequately tested), old, weak and positive (tested badly, with a favourable result), and negative (tested adequately and failed). Rau răm's bone and memory claims do not fit neatly into any single one of these, which is itself worth stating plainly rather than forcing a fit.
For the formula — mulberry plus rau răm together — the evidence is genuinely closer to the "old, weak and positive" category, except it is not old: it is recent (2018 and 2022), from a named academic centre, randomized and placebo-controlled, with safety monitoring. Its real weaknesses are different from the usual "old, weak" pattern: modest sample size (45 participants, roughly 15 per arm), a single research group with no independent replication, biochemical surrogate endpoints rather than hard clinical outcomes (bone-turnover markers rather than fracture rates or DXA-measured bone density; a cognitive test battery rather than a validated dementia or diagnosed-impairment outcome), and now a correction notice on the foundational preclinical paper from a journal with a documented recent history of integrity problems.
For rau răm specifically, tested alone, the evidence remains squarely absent — exactly as absent as it was before this page was written, because these trials never actually tested that. The genuine correction this page makes to the main page is narrower than "rau răm has clinical evidence." It is: "a formula containing rau răm has modest, real, unreplicated clinical evidence, and untangling rau răm's own contribution to it is an open question nobody has answered."
What This Does and Does Not Support
- What exists: two real randomized, double-blind, placebo-controlled human trials of a mulberry–rau răm congee, run by the same academic group, showing modest favourable changes in bone-turnover markers and working-memory measures over eight weeks at 1,500 mg/day, with a coherent (if unreplicated) rat-study precursor and a plausible, literature-consistent mechanistic hypothesis (acetylcholinesterase and monoamine oxidase suppression) for the cognitive result.
- What does not exist: any trial of rau răm alone, at any dose, for any outcome; any independent replication of either trial; any hard clinical endpoint (fractures, diagnosed cognitive decline) rather than a biochemical or performance-test surrogate; and any account of what fraction of the effect, if any, is attributable to rau răm rather than mulberry.
- What this means practically: this is the closest thing to real human evidence anywhere in rau răm's literature, and it should not be dismissed — but it is evidence about a specific two-herb product, not a basis for treating rau răm itself, eaten as a kitchen herb or taken as a solo supplement, as a bone- or memory-supporting intervention. A reader interested in the actual tested product would need to identify and evaluate that specific congee formulation, not assume rau răm alone reproduces it.
Key Research Papers
- Sungkamanee S, Wattanathorn J, Muchimapura S, Thukham-mee W. Antiosteoporotic effect of combined extract of Morus alba and Polygonum odoratum. Oxidative Medicine and Cellular Longevity. 2014;2014:579305 (corrected 2026). — PubMed
- Correction to "Antiosteoporotic Effect of Combined Extract of Morus alba and Polygonum odoratum." Oxidative Medicine and Cellular Longevity. 2026;2026:9864725. — PubMed
- Wattanathorn J, Somboonporn W, Sungkamanee S, Thukummee W, Muchimapura S. A double-blind placebo-controlled randomized trial evaluating the effect of polyphenol-rich herbal congee on bone turnover markers of the perimenopausal and menopausal women. Oxidative Medicine and Cellular Longevity. 2018;2018:2091872. — PubMed
- Wattanathorn J, Somboonporn W, Thukham-Mee W, Sungkamnee S. Memory-enhancing effect of 8-week consumption of the quercetin-enriched culinary herbs-derived functional ingredients: a randomized, double-blind, placebo-controlled clinical trial. Foods. 2022;11(17):2678. — PubMed
- Mulberry polyphenols promote bone formation and alleviate bone loss via dual regulation of bone metabolism. Journal of Ethnopharmacology. 2026. — PubMed. Morus alba tested alone — not this congee, and not rau răm.
- Chansiw N, Champakam S, Chusri P, Pangjit K, Srichairatanakool S. Quercetin-rich ethanolic extract of Polygonum odoratum var Pakphai leaves decreased gene expression and secretion of pro-inflammatory mediators in lipopolysaccharide-induced murine RAW264.7 macrophages. Molecules. 2022;27(12):3657. — PubMed. Independent confirmation of rau răm's own quercetin content.
- Harnessing essential oils for acetylcholinesterase inhibition: a literature review. Phytotherapy Research. 2025. — PubMed. General mechanism context, not specific to this herb.
- Evaluation of salivary bone turnover markers and vitamin D as non-invasive, early predictive indicators of bone health in pre-, peri-, and post-menopausal women. BMC Women's Health. 2026. — PubMed. General context on how bone-turnover markers are used and interpreted in this population.
- Khuayjarernpanishk T, Sookying S, Duangjai A, et al. Anticancer activities of Polygonum odoratum Lour.: a systematic review. Frontiers in Pharmacology. 2022;13:875016. — PubMed. Confirms no other human trial exists for this species outside the one congee pairing described on this page.
- Duangjai A, Parseatsook K, Sajjapong W, Saokaew S. Assessment of Polygonum odoratum Lour. leaf extract on rat's ileum contraction and the mechanisms involved. Journal of Medicinal Food. 2020;23(11):1169–1175. — PubMed. The only other mechanism study on this species, unrelated to bone or cognition.