Wen Ge
StarMeretrix meretrix L.
☯ TCM Properties
Clears Heat from the Lungs; Resolves Phlegm; Dissipates Nodules and Softens Hardness; Promotes Urination and Drains Dampness; Controls Acidity and Stops Pain; Absorbs Dampness and Heals Sores
Traditional Chinese Uses
Wen Ge (meretrix clam shell, clamshell) is a cold, salty mineral-rich substance used in Chinese medicine to clear Heat, transform stubborn Phlegm, and soften hard accumulations. It is commonly used for coughs with thick, sticky Phlegm, goiter and thyroid nodules from Phlegm accumulation, and excessive thirst and acid regurgitation from Stomach Heat. In its calcined form, it strongly neutralizes stomach acid for hyperacidity-related pain. Applied externally as a powder, it dries and soothes eczema, skin sores, and weeping lesions.
Botanical Description
Wen Ge is not a plant but the shell of the Asiatic hard clam, Meretrix meretrix (Linnaeus), a bivalve mollusc in the family Veneridae inhabiting sandy intertidal and shallow subtidal zones along the coasts of eastern and southeastern Asia. The shell is solid, equivalve, triangular-ovate to subtrigonal, typically 4-9 cm long, with a smooth, polished exterior bearing fine concentric growth lines and variable coloration ranging from cream and grey-brown to glossy purplish-brown with darker zig-zag patterns. The interior is porcelain white, often tinged purple at the posterior margin. For medicinal use the shells are collected, cleaned, sun-dried, and frequently calcined before being pulverised.
Active Constituents
Calcium carbonate (calcite / aragonite)
Inorganic carbonate mineralConcentration: Dominant component of the shell (~90%+)
The principal mineral of the clam shell, present as calcite and/or aragonite. It underlies the shell's traditional antacid-like actions of controlling acidity and stopping pain, and its astringent, drying effect on damp sores.
Conchiolin (organic shell matrix protein)
Structural protein / glycoprotein matrixConcentration: Minor organic fraction of the shell
An insoluble proteinaceous matrix distributed as microtubules within the calcium carbonate that reinforces the shell. It represents the organic component of the mineralized material.
Calcium phosphate and trace minerals
Inorganic salts / trace elementsConcentration: Trace (magnesium, strontium, iron, aluminium)
Small amounts of calcium phosphate and trace metals accompany the carbonate matrix. These contribute to the mineral supplementation and the drying, nodule-softening functions attributed to the calcined shell.
Meretrix polysaccharides (MMP-2, MMP-3, MMPX-B2)
Polysaccharides (glucomannan / glucogalactan)Concentration: Isolated from the clam (soft tissue and organism)
Glucose/galactose-containing polysaccharides purified from Meretrix meretrix that stimulate macrophages to release cytokines and show immune-enhancing, antioxidant and antitumor activity in laboratory models. These reflect the broader medicinal value of the organism beyond the mineral shell.
Amino acids and peptides
Free amino acids / bioactive peptidesConcentration: Minor (associated with the organic matrix and soft tissue)
Free amino acids and small peptides characterized from M. meretrix contribute to reported antioxidant and detoxifying activities of the animal.
⚠ Drug Interactions
Tetracycline and fluoroquinolone antibiotics
The shell is essentially calcium carbonate. Divalent calcium chelates tetracyclines and fluoroquinolones in the gut, forming poorly absorbed complexes. This is well established for calcium carbonate and is extrapolated to the crude calcined shell used in decoction.
Clinical note: Separate ingestion from these antibiotics by at least 2-4 hours if the calcined shell is taken in substantial amounts.
Levothyroxine
Calcium carbonate can bind levothyroxine and reduce its gastrointestinal absorption. Because the shell is predominantly calcium carbonate, concurrent use could theoretically lower thyroxine levels.
Clinical note: Where the shell is used as a calcium-rich mineral drug, take levothyroxine at least 4 hours apart and monitor thyroid function.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6-15g | Daily | — | — | — |
Preparation Methods
Calcined shell powder (煅)
Parts: shell
The cleaned shell is calcined until brittle, then ground to a fine powder. Calcining enhances the astringent, acid-controlling and nodule-softening actions; the powder is taken in small doses or added to decoctions, often used for acid reflux, phlegm nodules and non-healing damp sores.
Decoction of crushed shell
Parts: shell
Crushed raw shell is decocted (typically pre-cooked/decocted longer than soft herbs because of its mineral nature) to clear Lung Heat, resolve Phlegm and dissipate nodules. It is combined with Phlegm-transforming and softening-hardness herbs.
Topical powder for sores
Parts: calcined shell
Finely powdered calcined shell is applied externally to weeping, damp sores and eczema to absorb Dampness and promote healing.
Clinical Studies
Structural and Immunological Activity Characterization of a Polysaccharide Isolated from Meretrix meretrix Linnaeus
A polysaccharide (MMPX-B2) composed of D-glucose and D-galactose (molar ratio ~3.5:1, ~510 kDa) was isolated from Meretrix meretrix. It stimulated murine macrophages to release cytokines in vitro, supporting an immune-enhancing mechanism for the clam's reputed tonic and detoxifying properties.
Historical Texts
Shen Nong Ben Cao Jing (Divine Farmer's Materia Medica)
Han dynasty (compiled c. 200 CE)Ben Cao Gang Mu (Compendium of Materia Medica), Li Shizhen
Ming dynasty, 1596References
- Li L, Li H, Qian J, He Y, Zheng J, Lu Z, Xu Z, Shi J. Structural and Immunological Activity Characterization of a Polysaccharide Isolated from Meretrix meretrix Linnaeus . Marine Drugs (2015) [DOI]
- Zhang Y, et al.. Structural elucidation and immune-enhancing activity of peculiar polysaccharides fractioned from marine clam Meretrix meretrix (Linnaeus) . International Journal of Biological Macromolecules (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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