Ark shell, also called cockle shell or Wa Leng Zi in mandarin, is a Chinese herb that is known by very few people since it is less commonly used in folk medicine. Its first record as a drug was found in Ming Yi Bie Lu (the Informal Records of Eminent Physicians), which was compiled by Tao Hongjing around 520 A.D. And it is usually rated as a low-grade herb. Today it is basically used for the treatment of stomach pain caused by phlegm accumulation or excess acidity, gastric and duodenal ulcers, tuberculosis, scrofula, rickets in children, and the like. Based on different needs, ark shells can be used calcined or processed with rice vinegar and salt accordingly to take advantage of its best health benefits.
What is ark shell?
From the standpoint of Chinese herbal medicine, it basically refers to the shells of arcidae species, in particular Arca subcrenata Lischke, Arca granosa Linnaeus, or Arca inflata Reeve. In China it is produced around the coastal areas and captured all year round for medicinal purpose. And the subsequent steps are to clean, slightly boil in boiling water, remove the meat, and finally dried in sun. Medicinally it is used broken and raw or calcined.
Arca subcrenata Lischke is slightly triangular or fan-shaped, 4 to 5cm long, and 3 to 4cm high. The outer shell is ridgy, with existing or off brown hair; the top is prominent and curled inward; from the top to the ventral side there are 30 to 34 shell radial ribs. Inner shell surface is smooth and white; the edge is with the depression corresponding to the ridge of the outer side. The hinge has a row of toothlets. It is hard, odorless, and tasteless. The shell contains large amounts of calcium carbonate and small amounts of calcium phosphate, magnesium, iron, silicates, sulfates, chlorides and organic matter. The total calcium accounts for more than 93% if calculated by calcium carbonate.
Arca granosa Linnaeus is 2.5 to 4cm in length and 2 to 3cm in height. Outer side is with no brown hair. Radial ribs are 18 to 21 and with protruding granules. Its shells contain more than 90% calcium carbonate and approximately 1.69% organic matter. In addition, it still contains small amounts of magnesium, iron, silicates, sulfates, phosphates and chloride. After calcined, calcium carbonate is decomposed and gets calcium chloride while the organic matter is destroyed.
Arca inflata Reeve is 7 to 9cm long and 6 to 8cm high. There are 42 to 48 radial ribs outside. Its shell contains a large amount of calcium carbonate and a small amount of calcium phosphate. Besides, it also contains aluminum silicate and inorganic elements, such as chlorine, chromium, copper, iron, potassium, manganese, sodium, nickel, phosphorus, sulfur, silicon, strontium, and zinc. And it has a specific enrichment capacity of nuclide manganese.
Ark shell health benefits
Modern pharmacology reveals that its ability of reducing gastric ulcer pain comes from calcium carbonate, which can neutralize stomach acid.
Ark shell, clam shells (Hai Ge Ke), and pumice (Fu Hai Shi) have quite similar medicinal uses in traditional Chinese medicine. However, it doesn’t mean that they are interchangeable. On the contrary, they need to be well distinguished clinically for proper uses.
All of the three are of salty in flavor and have the common function of eliminating phlegm, softening hardness and dissipating binds. As a result, all of them can be used to treat phlegm-fire stagnation induced scrofula, subcutaneous nodule, goiter and tumor; clam shell and pumice stone can also treat cough and asthma accompanied with thick yellow sputum that is caused by lung heat and phlegm-fire since both of them is capable of clearing lung and eliminating phlegm; clam shell and ark shell are also good at treating stomach discomfort and acid reflux since they can neutralize acidity and relieve pain.
And they do have their own advantage respectively on healing properties. Clam shell is still capable of inducing diuresis to alleviate edema. So it is often used for the treatment of edema and difficult urination; pumice stone can treat bloody stranguria and urolithiasis by inducing diuresis; ark shell removes blood stasis and disperses phlegm. Hence, it treats mass in the abdomen and hepatosplenomegaly.
Sample ark shell recipes on herbal remedies
The Chinese Pharmacopoeia says that it is salty in flavor and neutral in nature. It covers meridians of lung, stomach, and liver. Crucial functions are dissolving phlegm, dispersing blood stasis, resolving hard lump, relieving hyperacidity, and stopping pain. Prime ark shell uses and indications include substantial amounts of lingering phlegm, difficulty coughing up thick, sticky mucus, goiter and tumor, scrofula, abdominal mass, stomachache, and acid regurgitation. Recommended dosage is from 9 to 15 grams in decoction. And please keep in mind to decoct it before other ingredients.
1) Han Hua Wan from Zheng Zhi Zhun Sheng (The Level-line of Patterns and Treatment). It is formulated with Hai Zao (Sargassum Seaweed), Kun Bu (Kombu), etc. to treat scrofula, goiter and tumor;
2) Wa Long Zi Wan from Wan Shi Jia Chao Fang (Wan’s Heirloom Prescriptions). It is fried, processed with vinegar, and used alone to cure abdominal mass and eliminate phlegm;
3) Wa Leng Zi Wan from Nu Ke Zhi Zhang (Full Knowledge of Gynecology). It is formulated with Xiang Fu (Cyperus), Tao Ren (Peach Seed), Mu Dan Pi (Tree Peony), Chuan Xiong (lovage), Da Huang (rhubarb), and Hong Hua (Safflower) to heal pain and no blood flow during menstruation. Lower abdomen is hard and full when pressed and it is kind of excess pain.
Clinical research of ark shells
50 cases of burns and scalds, including second degree, have been treated with the combination of ark shell and vegetable oil at the ratio of 1:1. The oil was directly applied to the wounds and wall of them were cured. – Si Chuan Yi Xue (Sichuan Medicine), 1982; 1:44.
Ark shell side effects and contraindications
Generally ark shell causes no adverse reaction when it is used in the treatments a variety of diseases like gastric and duodenal ulcers. But there were individual cases reported with facial swelling, blood in the urine, cloudy urine, recurrent urinary tract infections and others. Ben Cao Yong Fa Yan Jiu (Studies of The Uses of Drugs in Chinese Materia Medica) says that it shouldn’t be used in the patients with no blood stasis and sputum retention.