Xiao Mai
StarTriticum aestivum L.
Traditionally used for
- Sleep
- Mood & calm
Cautions & contraindications
- Liver conditions
- Kidney conditions
☯ TCM Properties
Nourishes the Heart and Calms the Spirit; Clears Heat and Eliminates Irritability; Benefits the Kidneys; Generates Fluids and Relieves Thirst
Traditional Chinese Uses
Xiao Mai (wheat grain) is a cool, sweet grain-food herb used in Chinese medicine primarily to nourish the Heart and calm the Spirit. It is used for the pattern of Liver Qi stagnation with Heat causing emotional lability — the "agitated discomfort" syndrome — with crying, emotional instability, inability to control oneself, and sleep disturbance. Light and gentle, it is a staple food-medicine that reflects the Chinese tradition of using ordinary foods for emotional and constitutional support.
Relationships
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Botanical Description
Triticum aestivum, common bread wheat, is an annual grass of the Poaceae family growing 60 to 130 cm tall, with hollow erect culms that branch only at the base into a tuft of fertile tillers. Leaves are linear, flat, 15 to 40 cm long and 0.6 to 1.5 cm wide, with a short membranous ligule and small clasping auricles at the base of each blade. The inflorescence is a dense terminal four-sided spike 5 to 12 cm long composed of two ranks of overlapping spikelets; each spikelet contains two to five florets enclosed by two stiff glumes. Many cultivars are awned, bearing long stiff bristles. The grain (caryopsis) is ovoid, 5 to 8 mm long, with a longitudinal ventral groove, ranging in color from pale amber to reddish-brown depending on cultivar. Mature seed used as Xiao Mai.
Active Constituents
Gliadins (including omega-5 gliadin)
Prolamin storage protein (gluten fraction, alcohol-soluble)Concentration: Gluten proteins make up roughly 80% of the protein of the wheat grain, and the grain is roughly 8-15% protein by weight; gliadins are about half of that gluten fraction
Gliadins carry the deamidated peptide epitopes that drive the HLA-DQ2/DQ8-restricted T-cell response of coeliac disease, and omega-5 gliadin (Tri a 19) is the dominant IgE allergen in wheat-dependent exercise-induced anaphylaxis. These are the constituents that make wheat unsafe rather than merely inert for a defined group of patients, and they are not removed by decoction.
Glutenins (including high-molecular-weight glutenin subunits)
Glutelin storage protein (gluten fraction)The second gluten protein fraction. High-molecular-weight glutenin subunits are the sensitising allergen in the minority of wheat-dependent exercise-induced anaphylaxis patients whose IgE does not bind omega-5 gliadin, so a negative omega-5 gliadin IgE does not exclude wheat anaphylaxis.
Amylase-trypsin inhibitors (ATIs)
Small disulphide-rich plant defence proteinsConcentration: Up to about 4% of total wheat protein
ATIs are strong activators of innate immunity through Toll-like receptor 4 on monocytes, macrophages and dendritic cells, driving intestinal and systemic inflammation independently of the adaptive gluten response. They are the leading candidate explanation for non-coeliac wheat sensitivity and for the innate component of coeliac inflammation.
Arabinoxylan
Non-starch polysaccharide (hemicellulose dietary fibre)The principal soluble and insoluble fibre of the wheat grain and bran. It is fermented by colonic flora and increases viscosity in the gut lumen, which is the mechanism behind fibre-mediated reductions in the absorption of some co-administered drugs.
Starch (amylose and amylopectin)
Glucan polysaccharideConcentration: Roughly 60-70% of the dry weight of the grain
The bulk of the grain and the reason a wheat decoction is nutritive rather than potent. It is relevant clinically mainly to glycaemic load in diabetic patients taking large habitual doses.
Wheat germ agglutinin
N-acetylglucosamine-binding lectinA lectin concentrated in the germ that binds glycosylated surfaces of the intestinal epithelium in vitro. Claims that it causes gut damage at dietary exposures in humans are not established, and it should not be presented to patients as a demonstrated hazard.
⚠ Drug Interactions
Gluten-free diet in coeliac disease and dermatitis herpetiformis
Xiao Mai is wheat. Coeliac disease is an HLA-DQ2/DQ8-restricted immune reaction to the gliadin and glutenin proteins of wheat, and the sole established treatment is lifelong strict avoidance of those proteins. A wheat decoction, a granule containing Fructus Tritici, or a Gan Mai Da Zao preparation therefore actively undoes the treatment, and the amount involved is well above the microgram-scale thresholds that provoke mucosal injury. The same applies to dermatitis herpetiformis, the cutaneous expression of coeliac disease.
Clinical note: Absolutely contraindicated in coeliac disease and dermatitis herpetiformis. Ask every patient about coeliac disease before prescribing any formula containing Xiao Mai, Fu Xiao Mai or malt (Mai Ya), and substitute rather than reduce the dose. Wheat is often invisible on an English herb list, so check the Latin as well as the pinyin.
NSAIDs and alcohol as cofactors in omega-5 gliadin allergy (wheat-dependent exercise-induced anaphylaxis)
In the largest published cohort (132 UK adults with omega-5 gliadin allergy), reactions required a cofactor in most patients: exercise in 80%, alcohol in 25% and NSAIDs in 9%. The cofactor increases gliadin peptide absorption and mast cell reactivity, so a wheat dose that is tolerated alone becomes anaphylactic when taken near exercise, alcohol or an NSAID. Specific IgE level did not predict reaction severity, and one third of patients continued to react despite dietary advice.
Clinical note: In any patient with a history of unexplained anaphylaxis, ask about wheat plus exercise, alcohol or NSAIDs before prescribing Xiao Mai, and refer for omega-5 gliadin specific IgE. Patients with a confirmed diagnosis should not take the herb at all, and must keep an adrenaline autoinjector.
Levothyroxine
Two routes converge. Wheat fibre increases luminal viscosity and binds levothyroxine, and a large habitual wheat intake taken close to the dose reduces absorption. Separately, in a patient with undiagnosed coeliac disease, wheat maintains the villous atrophy that itself causes levothyroxine malabsorption and unexplained dose escalation. Autoimmune thyroid disease and coeliac disease co-occur far more often than chance.
Clinical note: Keep a wheat-containing decoction at least four hours away from the levothyroxine dose. If a thyroid patient's TSH is unstable on an apparently adequate dose, consider coeliac serology rather than simply increasing the levothyroxine.
Oral drugs whose absorption is reduced by dietary fibre (e.g. digoxin, some bisphosphonates)
The arabinoxylan fibre load of a wheat decoction or of wheat bran raises intraluminal viscosity and can slow or reduce the absorption of drugs taken at the same time. The effect is generic to high-fibre intake rather than specific to this herb and is usually clinically small at ordinary decoction doses.
Clinical note: Separate the decoction from narrow-margin oral drugs by two hours. No monitoring change is needed for most patients.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 50–100 g | Daily | — | — | Standard oral dose per Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 384. Exact wording: Normally, 50–100 g is decocted with water as an oral |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Nourishing the Heart combined with sweet moderating of acute distress, which calms the spirit in restless organ disorder.
Restless organ disorder (zang zao) with unpredictable weeping and emotional distress.
Core pair of a classical formula — Gan Mai Da Zao Tang, Jin Gui Yao Lue (Zhang Zhongjing)
Evidence Tier
Strong evidence · 3 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
1
0 verified · 1 unverified
In vitro / animal
1
0 verified · 1 unverified
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
A Multicenter Evaluation of Diagnosis and Management of Omega-5 Gliadin Allergy (Also Known as Wheat-Dependent Exercise-Induced Anaphylaxis) in 132 Adults
Retrospective analysis of 132 adults with omega-5 gliadin allergy across four UK allergy centres. Diagnosis was delayed one to five years in 40% and more than five years in 29%. Cofactors were exercise (80%), alcohol (25%) and NSAIDs (9%), with 11% reacting without an identifiable cofactor. Specific IgE level did not predict severity. Gluten-free diet and avoiding wheat around exercise reduced subsequent reactions by 67% and 69% respectively, but one third of patients continued to react, so an adrenaline autoinjector remains necessary.
Wheat amylase trypsin inhibitors drive intestinal inflammation via activation of toll-like receptor 4
Identified the wheat amylase-trypsin inhibitors, rather than gluten peptides, as strong activators of innate immunity through TLR4-MD2-CD14 on monocytes, macrophages and dendritic cells, in human cell systems and in mice. This gives a mechanism by which wheat can provoke intestinal inflammation independently of the coeliac adaptive response, and underlies the concept of non-coeliac wheat sensitivity.
Herbal medicine (Gan Mai Da Zao decoction) for depression: A systematic review and meta-analysis of randomized controlled trials
Thirteen randomised trials of Gan Mai Da Zao decoction, the classical formula in which Xiao Mai is the chief herb, were included from 298 screened. All had a high risk of bias. The review found no evidence of superiority over antidepressants for major depression, post-surgical depression or depression in the elderly; only in post-stroke depression did pooling favour the decoction (RR 1.17), and the authors rated that evidence low quality. This is the best clinical evidence that exists for the drug and it is weak.
⚠ Safety & Contraindications
- Liver conditions
- Kidney conditions
Contraindications
It is not suitable for patients with weak foot with puffiness, pĭ and fullness, sunstroke, or liver-stomach pain.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, p. 384.
Historical Texts
Jin Gui Yao Lue
Han dynastyMing Yi Bie Lu
Southern and Northern dynastiesBen Cao Gang Mu
Ming dynastyReferences
- Lebwohl B, Sanders DS, Green PHR. Coeliac disease . The Lancet (2018) [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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