Mai Ya
StarHordeum vulgare
Synonyms: Hordeum vulgare var. coeleste, Hordeum vulgare var. multispiculum, Hordeum strobelense, Hordeum vulgare var. subnudipiramidatum, Hordeum barbaricum, Hordeum coeleste, Hordeum vulgare var. trofimovskajae, Hordeum nudum-distichum, Hordeum vulgare subsp. medioasiaticum, Hordeum ircutianum, Hordeum daghestanicum, Hordeum sativum, Hordeum praecox, Frumentum sativum, Hordeum vulgare var. breviaristatum, Hordeum vulgare var. micrurum, Hordeum vulgare var. griseinudum, Hordeum vulgare var. nudinipponicum, Hordeum vulgare var. subnudum, Hordeum vulgare var. nipponicum, Hordeum himalayense, Hordeum vulgare var. zeocrithideficiens, Hordeum vulgare var. harlanii, Hordeum vulgare var. chungense, Hordeum transcaucasicum, Hordeum michalkowii, Hordeum vulgare var. latibrevisetum, Hordeum vulgare var. tetrapallidum, Hordeum parvum, Hordeum vulgare var. interpallidum, Hordeum vulgare var. bachteevii, Hordeum vulgare subsp. tetrastichum, Hordeum elongatum, Hordeum hibernaculum, Hordeum vulgare var. glabrierectum, Hordeum jarenskianum, Hordeum mandshuroides, Hordeum vulgare var. macrosteron, Hordeum vulgare var. valentinae, Hordeum vulgare var. subnutans, Hordeum revelatum, Hordeum vulgare var. griseinigrum, Hordeum vulgare var. uljassutaicum, Hordeum vulgare var. ancoberense, Hordeum aestivum, Hordeum vulgare var. glabrispicatum, Hordeum vulgare var. ismailii, Hordeum vulgare var. saidii, Hordeum pensanum, Hordeum bifarium, Hordeum nigrum, Hordeum sativum subsp. vulgare, Hordeum vulgare var. pallidum, Hordeum polystichon, Hordeum caspicum, Frumentum hordeum, Hordeum vulgare var. daghestanicum, Hordeum lapponicum, Hordeum vulgare var. nudijaponicum, Hordeum vulgare var. subneogenes, Hordeum polystichon var. hexastichon, Hordeum vulgare var. tibetanum, Hordeum vulgare var. japonicum, Hordeum taganrocense, Hordeum vulgare var. syriacum, Hordeum vulgare var. glabrigracilius, Hordeum vulgare var. latirevelatum, Hordeum vulgare var. coerulescens, Secale orientale, Hordeum kiarchanum, Hordeum brachyatherum, Hordeum pyramidatum, Hordeum pamiricum, Hordeum hexastichon var. mandshuricum, Hordeum vulgare var. lvovii, Hordeum kalugense, Hordeum vulgare var. addis-abebae, Hordeum vulgare var. glabrideficiens, Hordeum polystichon var. hackelii, Hordeum hibernans, Hordeum vulgare var. suberectum, Hordeum hexastichon, Hordeum vulgare var. kobdicum, Hordeum vulgare var. revelatum, Hordeum vulgare var. gobicum, Hordeum vulgare f. hexastichon, Hordeum vulgare var. rarum, Hordeum vulgare var. hexastichon, Hordeum perversum, Hordeum vulgare var. subpyramidatum, Hordeum vulgare subsp. polystichon, Hordeum violaceum, Hordeum nekludowii, Hordeum vulgare subsp. antasiaticum, Hordeum vulgare var. brachyura, Hordeum vulgare var. mandshuricum, Hordeum durum, Hordeum vulgare var. nanum, Hordeum vulgare var. nigrinudum, Hordeum tetrastichum var. nudum, Hordeum vulgare var. sinojaponicum, Hordeum vulgare var. nigrum, Hordeum tanaiticum, Hordeum scabriusculum, Hordeum walpersii, Hordeum vulgare var. ibericum, Hordeum vulgare var. euryhypatherum, Hordeum vulgare var. latinudipyramidatum, Hordeum vulgare var. colonicum, Hordeum polystichon var. vulgare, Hordeum latum, Hordeum septentrionale, Hordeum americanum, Hordeum hirtiusculum, Hordeum vulgare var. brevispicatum, Hordeum vulgare var. tetranutans, Hordeum karzinianum, Hordeum coeleste var. barbatum, Hordeum hexastichon var. densum, Hordeum defectoides, Hordeum vulgare subsp. hexastichon, Hordeum vulgare var. tortile, Hordeum vulgare var. palestinicum, Hordeum sativum var. trifurcatum, Hordeum vulgare var. hangaicum, Hordeum vulgare var. viride, Hordeum vulgare var. glabribrevisetum, Hordeum sativum subsp. hexastichon, Hordeum vulgare var. africanum, Hordeum vulgare var. patimatae, Hordeum stassewitschii, Hordeum vulgare var. zuleichatae, Hordeum vulgare var. sinicum, Hordeum vulgare var. sikangense, Hordeum leptostachys, Hordeum vulgare var. glabriviride, Hordeum vulgare var. mongolicum, Hordeum vulgare var. insularum, Hordeum laevipaleatum, Hordeum vulgare var. sessilifurcatum, Hordeum horsfordianum, Hordeum vulgare var. hypatherum, Hordeum gymnodistichum, Hordeum vulgare var. aestivum, Hordeum vulgare var. brunneinudum, Hordeum vulgare var. chinense, Hordeum hexastichon var. laxum, Hordeum vulgare var. hybernum, Hordeum tetrastichum, Hordeum vulgare var. abdulbasirovii, Hordeum vulgare var. atratum, Hordeum vulgare var. lukyanovae, Hordeum vulgare var. leioheterolepis, Hordeum juliae, Hordeum heterostychon, Hordeum mandshuricum, Hordeum vulgare var. subzeocrithon, Hordeum vulgare var. solitarum, Hordeum vulgare var. hadaka, Hordeum vulgare var. urgaicum, Hordeum vulgare var. chalunicum
Traditionally used for
- Digestion
- Energy & fatigue
Cautions & contraindications
- Breastfeeding
☯ TCM Properties
Reduces Food Stagnation, improves digestion and strengthens the Stomach; Inhibits lactation; Facilitates the smooth flow of Liver Qi
Traditional Chinese Uses
Mai Ya (barley sprout, malt) is a mild herb used in Chinese medicine to reduce food stagnation from starchy foods, grains, and fruit, to stimulate appetite in Spleen Qi deficiency with weak digestion, and to treat poorly digested milk in infants. At high doses, it disperses Liver Qi stagnation and is traditionally used to suppress lactation when weaning. It is a gentle, food-grade herb frequently combined with Shan Zha and Shen Qu as the classical digestive tonic trio.
Western Herbalism Properties
Used In Formulas (2)
Relationships
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Botanical Description
Hordeum vulgare is an annual grass growing 60-120 cm tall, with hollow, jointed culms and flat, linear leaves 10-20 cm long with prominent auricles that clasp the stem. The inflorescence is a dense spike bearing three spikelets at each rachis node (the characteristic barley arrangement). Each spikelet contains one grain (caryopsis) and is often associated with long, stiff awns. In TCM, the germinated grain (Mai Ya) is used, made by sprouting the barley grain.
Cultivated in fields throughout temperate regions worldwide; one of the oldest and most widely grown cereal crops. Native to the Fertile Crescent region of the Middle East.
Hordeum vulgare is one of the world most widely cultivated cereal crops. It is a domesticated species. Wild barley (H. vulgare subsp. spontaneum) is found in the Middle East and Central Asia. No conservation concerns for the cultivated form.
Active Constituents
Hordenine (N,N-dimethyltyramine)
Phenethylamine alkaloidConcentration: total alkaloids of germinated barley have been measured at about 42.7 mg hordenine-equivalent per gram of drug by acid-dye colorimetry; that figure is a total-alkaloid estimate expressed as hordenine, not the hordenine content itself
The compound that makes Mai Ya pharmacologically distinctive rather than merely digestive. Hordenine is a functionally selective dopamine D2 receptor agonist; D2 agonism at the anterior pituitary suppresses prolactin release, which is the mechanism of both the traditional lactation-suppressing use at high dose and the modern Chinese use for hyperprolactinaemia. Total alkaloid content of malt varies with sprout length, reported to peak at about 0.75 cm of bud, so the germination endpoint changes the potency of this action.
N-Methyltyramine
Phenethylamine alkaloidThe other dopamine D2 receptor agonist identified in germinated barley and tracked through the brewing process alongside hordenine. It contributes to the same prolactin-suppressing pharmacology and to the total alkaloid figure quoted for the drug.
Gramine
Indole alkaloidA barley alkaloid quantified together with hordenine by HPLC in the barley chemical-ecology literature. It is principally a seedling and leaf constituent rather than a marker of the malted grain, so it should not be presented as a constituent of the medicinal sprout without batch-specific data.
alpha-Amylase and beta-amylase (diastase)
Starch-hydrolysing enzymeInduced by germination and the conventional explanation for the food-stagnation indication. Being proteins they are heat-labile: raw or lightly stir-fried Mai Ya retains them, heavily stir-fried (Chao Mai Ya) and charred (Mai Ya Tan) material progressively loses them. This is the practical reason the raw drug is preferred where digestion of starchy food stagnation is the aim.
(1,3;1,4)-beta-D-Glucan
Soluble dietary fibre polysaccharideThe barley fibre with the best human evidence of any constituent here: a meta-analysis of randomised controlled trials found barley beta-glucan lowers LDL cholesterol and total cholesterol. The trials used barley foods at food-scale intakes, not the medicinal dose of Mai Ya, so this supports barley as a food rather than the herb as a lipid drug.
Hordein
Prolamin storage protein (gluten)Barley's gluten protein. Mai Ya is therefore not gluten-free and is unsafe in coeliac disease and in non-coeliac gluten sensitivity, however it is processed - malting does not remove hordein. Where a sprouted-grain digestive is needed in a coeliac patient, millet sprout (Su Ya / Gu Ya, Setaria italica) is the substitution that avoids the problem.
Maillard reaction products of stir-frying
Thermally generated condensation productsFormed when the sprout is stir-fried, and shown to promote the intestinal absorption of the drug's active ingredients. This gives a chemical reason why processed Mai Ya is not simply a weaker version of the raw drug: stir-frying destroys enzyme activity but improves absorption of the small-molecule actives.
⚠ Drug Interactions
Breastfeeding and galactagogue therapy (including domperidone and metoclopramide used for milk supply)
At the high doses recorded in Chinese practice, conventionally 30 to 120 g, Mai Ya suppresses prolactin secretion and reduces milk production - this is a deliberate therapeutic use for weaning and for breast distension, not an incidental effect. The mechanism is dopamine D2 receptor agonism by hordenine and N-methyltyramine at the pituitary lactotrophs. In hyperprolactinaemic rats, malt of different bud lengths lowered serum prolactin, reduced the number of prolactin-positive pituitary cells and their mRNA expression, and raised hypothalamic dopamine D1 and D2 receptor numbers. Domperidone and metoclopramide raise milk supply by the opposite action, D2 blockade, so the two are directly pharmacodynamically opposed. Note that the small quantities of malt in food and beer are not the same exposure as a 60 to 120 g decoction dose.
Clinical note: Do not prescribe Mai Ya at digestive doses without asking whether the patient is breastfeeding or wishes to be, and avoid it entirely in a mother establishing supply. When used deliberately for weaning or for engorgement, say so explicitly to the patient - and understand the dose direction: low doses are used in Chinese practice to promote lactation while high doses suppress it, so an imprecise dose can produce the opposite of the intended effect.
Antipsychotics and other dopamine D2 antagonists (risperidone, amisulpride, sulpiride, haloperidol, metoclopramide)
Total barley maiya alkaloids prevented the prolactin elevation caused by antipsychotic drugs in rats and reduced dopamine receptor D2 expression through epigenetic mechanisms, and a separate study showed the alkaloids inhibit prolactin secretion by acting on D2 receptor and protein kinase A targets. This has been proposed as a use rather than a hazard - treating antipsychotic-induced hyperprolactinaemia - but the same D2 agonism is in principle opposed to the antipsychotic's mechanism. All the evidence is rodent and cell-based; no human co-administration study exists.
Clinical note: Do not add or remove Mai Ya at high dose in a psychiatrically stable patient on an antipsychotic without telling the prescriber. If it is being used for drug-induced hyperprolactinaemia, that should be a shared decision with the psychiatrist, not a substitution for reviewing the antipsychotic.
Dopamine agonists (bromocriptine, cabergoline)
Both act at the D2 receptor in the same direction as hordenine, so the effects should add. Hordenine also showed an antiprolactinoma effect in rats through inhibition of MAPK signalling, the same indication cabergoline is used for. No human data on the combination, and the potency of dietary or medicinal hordenine relative to cabergoline is unknown, so this is graded theoretical.
Clinical note: Not a reason to avoid the combination, but check prolactin if a patient on cabergoline or bromocriptine starts high-dose Mai Ya, and do not assume the herb can replace the drug in macroprolactinoma.
Monoamine oxidase inhibitors (phenelzine, tranylcypromine, moclobemide, linezolid)
Hordenine and N-methyltyramine are N-methylated tyramine derivatives, and tyramine itself is the classic substrate behind the hypertensive reaction to MAO inhibitors. Whether these particular methylated analogues produce a clinically meaningful pressor effect at malt doses has not been tested, so this is an inference from chemical class rather than a documented interaction, and it is recorded here only because the class of compound is the one that matters for MAOI diet advice.
Clinical note: Reasonable to avoid high-dose Mai Ya in a patient on a non-selective MAO inhibitor, alongside the standard tyramine restrictions, rather than to reassure them that the herb is unrelated.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 10–15 g | daily | — | adult | 中国药典 2020年版 一部 【麦芽】【用法与用量】10～15g；回乳炒用60g。 — Chinese Pharmacopoeia 2020, Vol. I. Use fried (chao) form to reduce food stagnation. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Gently reduce food stagnation and awaken the spleen and stomach without harming stomach qi.
Poor appetite and indigestion, especially after illness or with spleen deficiency.
Named pairing — Lü Jingshan, Shi Jinmo Dui Yao
Evidence Tier
Strong evidence · 7 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
1
1 verified · 0 unverified
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
6
1 verified · 5 unverified
Show 6 studies
- Total barley maiya alkaloids inhibit prolactin secretion by acting on dopamine D2 receptor and protein kinase A targets
- Total Barley Maiya Alkaloids Prevent Increased Prolactin Levels Caused by Antipsychotic Drugs and Reduce Dopamine Receptor D2 via Epigenetic Mechanisms
- Antiprolactinoma Effect of Hordenine by Inhibiting MAPK Signaling Pathway Activation in Rats
- Monitoring of the dopamine D2 receptor agonists hordenine and N-methyltyramine during the brewing process and in commercial beer samples
- UPLC-Q-TOF-MS/MS analysis on the chemical composition of malts under different germination cycles and prepared with different processing methods
- Promoting effect of the Maillard reaction products produced during the stir-frying process of Hordei Fructus Germinatus on the intestinal absorption of active ingredients in Hordei Fructus Germinatus
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Total barley maiya alkaloids inhibit prolactin secretion by acting on dopamine D2 receptor and protein kinase A targets
The total alkaloid fraction of barley maiya suppressed prolactin secretion, with the effect traced to dopamine D2 receptor engagement and downstream protein kinase A signalling. This is the mechanistic core of the lactation-suppressing action and it studied Hordeum vulgare malt specifically.
Total Barley Maiya Alkaloids Prevent Increased Prolactin Levels Caused by Antipsychotic Drugs and Reduce Dopamine Receptor D2 via Epigenetic Mechanisms
Barley maiya alkaloids blocked the prolactin rise produced by antipsychotic drugs in rats and downregulated dopamine receptor D2 through epigenetic mechanisms. Basis for the antipsychotic interaction recorded above, in both its therapeutic and its cautionary reading; rodent data only.
Antiprolactinoma Effect of Hordenine by Inhibiting MAPK Signaling Pathway Activation in Rats
Isolated hordenine, the principal barley malt alkaloid, reduced prolactinoma growth in rats with suppression of MAPK pathway activation. Attributes the drug's endocrine effect to a single identified compound; rat study, no human evidence.
Monitoring of the dopamine D2 receptor agonists hordenine and N-methyltyramine during the brewing process and in commercial beer samples
Confirms hordenine and N-methyltyramine as dopamine D2 receptor agonists and quantifies them through malting and brewing. Establishes that the D2 activity is a property of germinated barley itself and survives processing, which is what makes the endocrine effect of Mai Ya credible rather than merely traditional.
β-glucan from barley and its lipid-lowering capacity: a meta-analysis of randomized, controlled trials
Pooled randomised controlled trials of barley beta-glucan and found significant reductions in total and LDL cholesterol. The only human randomised evidence attaching to any constituent of this drug, but it concerns barley as a food at fibre-scale intakes and does not validate Mai Ya as a lipid-lowering herb.
UPLC-Q-TOF-MS/MS analysis on the chemical composition of malts under different germination cycles and prepared with different processing methods
Compared malt composition across germination times and across raw, stir-fried and charred preparations. Provides the chemical basis for treating raw Mai Ya, Chao Mai Ya and Mai Ya Tan as distinct drugs rather than interchangeable grades of one.
Promoting effect of the Maillard reaction products produced during the stir-frying process of Hordei Fructus Germinatus on the intestinal absorption of active ingredients in Hordei Fructus Germinatus
Maillard reaction products formed during stir-frying of germinated barley increased the intestinal absorption of the drug's active constituents. Explains why the processed drug is not simply a heat-degraded version of the raw one, and supports the traditional practice of stir-frying for some indications.
⚠ Rule-Based Cautions
These entries come from the deterministic rule tables that gate Verscienta's formula tools — classical pair prohibitions, pregnancy and lactation contraindications, and dose ceilings.
Breastfeeding
Avoid suppresses lactation (esp. high dose)
Historical Texts
Ming Yi Bie Lu
Southern and Northern dynastiesBen Cao Gang Mu
Ming dynastyReferences
- Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development. Barley . LactMed, NCBI Bookshelf NBK501827 (2024)
- Wu Zhiqian; Liang Shuxiao; Zhang Xinyu; Ma Mengting; Sui Zhongquan; Corke Harold. Anti-dyspeptic effects and comparative structural analysis of polysaccharides from hulled and hulless barley-based Hordei Fructus Germinatus . Carbohydrate Polymers (2026) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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