Traditionally used for
- Digestion
Cautions & contraindications
- Diabetes
☯ TCM Properties
Strengthens the Spleen and Promotes Digestion; Strengthens the Spleen and Opens the Appetite; Descends Qi and Relieves Distension
Traditional Chinese Uses
Gu Ya (rice sprout) is a mild, warm herb used in Chinese medicine to dissolve food stagnation from undigested rice and starchy foods, strengthen the Spleen and Stomach, and improve digestion. Similar in action to Mai Ya (barley sprout) but with a preference for stagnation from grains and rice specifically, it is used for Spleen-Stomach deficiency with poor appetite, bloating, and sluggish digestion. As a food-grade herb, it is one of the gentlest and most suitable digestive herbs for those with weak constitutions.
Relationships
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Botanical Description
Setaria italica, foxtail millet, is an annual warm-season cereal grass of the family Poaceae, cultivated for at least eight thousand years across northern China and now grown throughout temperate and subtropical regions for grain and fodder. It is an erect tufted grass 60 to 150 cm tall, with hollow culms and flat, linear-lanceolate leaf blades 10 to 30 cm long bearing ciliate ligules. The inflorescence is a dense, cylindrical, often somewhat lobed or interrupted spike-like panicle 10 to 30 cm long, with bristly involucres surrounding each spikelet, giving the head its bristly foxtail appearance. The small, ovoid, hard caryopses (grains) ripen yellow, orange, reddish, or blackish depending on variety. For Gu Ya, the cleaned ripe grain is soaked in water until short rootlets emerge, then carefully dried, yielding sprouted (germinated) millet.
Active Constituents
alpha-Amylase and beta-amylase (diastase)
Starch-hydrolysing enzymeConcentration: activity absent in the ungerminated grain, rising through the first days of sprouting and falling again with over-long germination
The pharmacologically obvious basis of the digestive action: germination induces amylase and phytase, and diastatic power rises significantly with germination time. These are proteins, so they are destroyed by heavy stir-frying and by prolonged boiling. If the digestive action is what is wanted, the raw or lightly stir-fried sprout added late to a decoction is the rational form, and a long-boiled decoction of charred sprout is not.
gamma-Aminobutyric acid (GABA)
Non-protein amino acidConcentration: reported to rise from about 7 mg/100 g in the ungerminated grain to about 38 mg/100 g after 48 h of germination
Accumulates during sprouting as glutamate decarboxylase and protease activity increase. It is the most-cited compositional change on germination and is the reason germinated millet is marketed as a functional food. No clinical effect at these intakes has been demonstrated for the medicinal drug.
Ferulic acid and feruloylquinic acid
Hydroxycinnamic acid (phenolic acid)Concentration: free feruloylquinic acid reported up by about 96 percent and free trans-ferulic acid by about 12 percent after three days of germination
The dominant free phenolics of germinating foxtail millet; N-feruloylserotonin and N-(p-coumaroyl)serotonin appear only after about two days of sprouting. They carry the antioxidant activity measured in vitro and are the compositional argument for using the sprout rather than the plain grain.
Prolamin (millet storage protein)
Cereal storage proteinThe main protein fraction of foxtail millet. Prolamin isolated from cooked foxtail millet lowered blood glucose in streptozotocin-diabetic mice, which is the mechanistic counterpart to the glucose-lowering seen with whole millet in humans. Unlike wheat gliadin and barley hordein, millet prolamin is not a coeliac-toxic gluten, so foxtail millet is generally suitable in coeliac disease - a genuine point of difference from Mai Ya in the same category.
Starch
PolysaccharideThe bulk of the grain, partly hydrolysed to reducing sugars during germination, which is why sprouted millet is sweeter and more easily digested than the raw grain.
⚠ Drug Interactions
Germinated rice (Dao Ya, Oryzae Fructus Germinatus, Oryza sativa)
This is the substitution that defines this drug in practice. In the Chinese Pharmacopoeia lineage Gu Ya is germinated Setaria italica (Setariae Fructus Germinatus) and Dao Ya is germinated Oryza sativa (Oryzae Fructus Germinatus), and the unambiguous name for the millet sprout is Su Ya. In the southern Chinese and most Western herb trade, however, material sold as Gu Ya is routinely germinated rice, and suppliers openly list Gu Ya as Fructus Oryzae Germinatus. The two are separable on inspection: millet sprouts are small and nearly spherical, roughly 2 mm across, while rice sprouts are longer and spindle-shaped, roughly 7 to 9 mm, with a longitudinal groove. Both are amylase-bearing sprouted cereals used for the same indication, so this is a labelling and reproducibility problem rather than a toxic one - but a study or formula that specifies Setaria italica cannot be assumed to have been made with it.
Clinical note: If the species matters, order Su Ya or specify Setariae Fructus Germinatus and check the grain shape and size on arrival. Also check sprouting rate and for insect damage, the usual quality failures in this drug.
Insulin, sulfonylureas, metformin and other glucose-lowering drugs
Foxtail millet improved glycaemic control in free-living subjects with impaired glucose tolerance in a self-controlled clinical trial, and prolamin from cooked foxtail millet lowered glucose in streptozotocin-diabetic mice. The effect is dietary and dose-dependent on how much of the staple is displaced, not a receptor-level drug interaction; the medicinal dose of the sprout is far smaller than the dietary intakes used in those studies, so the risk is mainly in patients who also adopt millet as a staple grain.
Clinical note: Worth mentioning to patients on insulin or a sulfonylurea who are advised to eat millet as a staple, and worth a period of closer glucose monitoring if they do. The medicinal dose of Gu Ya alone is unlikely to matter.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 9–15 g | Daily | — | — | 中国药典 2020 【用法与用量】9～15g。 【性味与归经】甘，温。归脾、胃经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
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
Moderate evidence · 4 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
0
Randomized controlled trial
0
Other clinical trial
1
1 verified · 0 unverified
Observational / case report
0
In vitro / animal
3
1 verified · 2 unverified
Show 3 studies
- Hypoglycemic Effect of Prolamin from Cooked Foxtail Millet (Setaria italic) on Streptozotocin-Induced Diabetic Mice
- Changes in the GABA and polyphenols contents of foxtail millet on germination and their relationship with in vitro antioxidant activity
- Accumulation of γ-aminobutyric acid and modifications of phenolic profiles and antioxidant capacity of foxtail millets during germination
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
The Glucose-Lowering Effect of Foxtail Millet in Subjects with Impaired Glucose Tolerance: A Self-Controlled Clinical Trial
Free-living subjects with impaired glucose tolerance improved their glycaemic control while consuming foxtail millet. Self-controlled design with no independent control group, so it is weaker than a randomised trial, and it studied the whole cooked grain as a staple food rather than the germinated medicinal drug.
Hypoglycemic Effect of Prolamin from Cooked Foxtail Millet (Setaria italic) on Streptozotocin-Induced Diabetic Mice
The prolamin fraction of cooked foxtail millet lowered blood glucose in streptozotocin-diabetic mice, identifying a protein rather than the fibre or phenolic fraction as a candidate active. Mouse study on an isolated fraction; the journal prints the binomial in the title as Setaria italic.
Changes in the GABA and polyphenols contents of foxtail millet on germination and their relationship with in vitro antioxidant activity
Quantified the rise in GABA and total polyphenols during germination of foxtail millet and correlated it with antioxidant activity in vitro. This is the source of the frequently quoted figures for GABA increase on sprouting and is food-science rather than clinical evidence.
Accumulation of γ-aminobutyric acid and modifications of phenolic profiles and antioxidant capacity of foxtail millets during germination
Tracked GABA and individual phenolics across days of germination, reporting large increases in free feruloylquinic acid and trans-ferulic acid by day three and the appearance of feruloyl- and coumaroyl-serotonins after two days. Useful for deciding how long the drug should be sprouted, but no biological or clinical endpoint was measured.
Historical Texts
Ben Cao Gang Mu
Ming dynastyThis 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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