Ha Ke
StarMeretrix meretrix L. / Cyclina sinensis Gmelin
☯ TCM Properties
Clears Lung Heat and Transforms Phlegm; Dissipates Nodules and Softens Hardness; Controls Acidity and Stops Pain; Promotes Urination and Reduces Edema; Absorbs Dampness and Heals Sores
Traditional Chinese Uses
Ha Ke (clam shell) is a cold, salty-tasting mineral substance that clears Lung Heat and transforms sticky phlegm, making it useful for productive coughs with thick yellow sputum, chest discomfort, and chronic respiratory conditions. It softens and disperses hardened lumps, including thyroid nodules and scrofula. When processed into calcined powder, it neutralizes stomach acid and helps stop abnormal leakage of body fluids.
Botanical Description
Ha Ke refers to the shells of marine bivalve mollusks in the family Veneridae, primarily Meretrix meretrix and Cyclina sinensis, harvested from coastal waters of eastern Asia. The shells are roughly triangular to oval, 3-7 cm across, with concentric growth ridges on the exterior; the outer surface ranges from cream and yellow-brown to grey or purplish, often with darker markings, while the interior is smooth and porcelain-white, sometimes with a violet tint near the margin. The shell is composed chiefly of calcium carbonate. For use in TCM, the empty shells are collected, cleaned, and either used raw, calcined, or ground to powder. As a substance it is classified as a salty, cold mineral-derived medicinal that clears heat, transforms phlegm, and softens hardness.
Active Constituents
Calcium carbonate (aragonite / calcite)
Inorganic carbonate salt (biomineral)Concentration: Approximately 90–99% of the shell
The dominant component of the clam shell; acts as an acid-neutralising (antacid) agent underlying the traditional actions of controlling acidity and stopping pain, and is a source of dietary calcium. On calcination (Duan) it converts partly to calcium oxide/hydroxide, increasing alkalinity and friability.
Elemental calcium
Mineral elementConcentration: More than 30% of the drug by weight
Bioavailable calcium liberated on dissolution; contributes to the antacid and astringent effects.
Conchiolin (shell matrix protein)
Structural glycoprotein matrixConcentration: Roughly 1–5% organic matrix
The organic framework binding the carbonate crystals; provides amino acids and, in the flesh-derived fractions of the mollusc, is linked to immunomodulatory bioactivity.
Chitin
Amino-polysaccharideConcentration: Minor component of the organic matrix
Component of the shell organic matrix contributing to its structural integrity.
Amino acids (glycine, aspartic acid, etc.)
Amino acids (from matrix protein)Concentration: Trace, from conchiolin
Released from the shell matrix protein; acidic amino acids such as aspartate participate in carbonate biomineralisation.
Trace elements (magnesium, strontium, iron, silicon)
Trace mineralsConcentration: Trace levels within the carbonate lattice
Trace minerals incorporated in the biomineral; of minor pharmacological but analytical significance for authentication of the shell drug.
⚠ Drug Interactions
Tetracycline and fluoroquinolone antibiotics
The high calcium-carbonate content chelates tetracyclines and fluoroquinolones in the gut, forming insoluble complexes that markedly reduce their absorption—a well-established calcium-antacid interaction.
Clinical note: Separate administration of the clam-shell preparation from these antibiotics by at least 2–4 hours.
Levothyroxine, oral bisphosphonates and oral iron
As a calcium-carbonate source it binds levothyroxine, bisphosphonates and iron salts in the gastrointestinal tract and raises gastric pH, decreasing their absorption.
Clinical note: Take these medications several hours apart from the clam-shell (calcium) preparation.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6-15g | Daily | — | — | — |
Preparation Methods
Decoction (raw shell, in cloth bag, decocted first)
Parts: Shell of Meretrix meretrix or Cyclina sinensis
Typically 6–15 g of the crushed shell wrapped in cloth and decocted before other herbs, used internally to clear Lung heat, transform phlegm and soften hardness/dissipate nodules.
Calcined shell powder (Duan Hai Ge Ke) for powders and pills
Parts: Calcined shell
The shell is calcined and ground to a fine powder (about 1–3 g taken internally, e.g., for hyperacidity), the calcined form being easier to pulverise. It is also applied externally to burns, eczema and weeping sores for its drying, absorbent action.
Clinical Studies
Structural and Compositional Changes in Two Marine Shell Traditional Chinese Medicines: A Comparative Analysis Pre- and Post-Calcination
Comparative analysis of marine-shell TCMs (including clam shell) before and after calcination, documenting the conversion of aragonite/calcite calcium carbonate and associated structural changes that underlie the different clinical uses of raw versus calcined (Duan) shell preparations.
Structural and Immunological Activity Characterization of a Polysaccharide Isolated from Meretrix meretrix Linnaeus
A water-soluble polysaccharide (MMPX-B2, ~510 kDa, glucose:galactose 3.51:1) from Meretrix meretrix stimulated murine macrophages to release cytokines in vitro. This concerns the clam soft tissue rather than the shell but documents bioactive components of the source mollusc.
Historical Texts
Shen Nong Ben Cao Jing (神农本草经, The Divine Farmer's Classic of Materia Medica)
Han dynasty (compiled c. 1st–2nd century CE)References
- Wu L, Liu C, Yao T, Shi Y, Shen J, Gao X, Qin K. Structural and Compositional Changes in Two Marine Shell Traditional Chinese Medicines: A Comparative Analysis Pre- and Post-Calcination . Journal of AOAC International, 107(4):704-713 (2024) [DOI]
- 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, 14(1):6 (2015) [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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