For many people, oyster shells, also known as Concha Ostreae in Latin and Mu Li in mandarin, are just something worthless that is to be disposed of. What they care about is the oyster meat since this is a seafood delicacy with tons of health benefits on digestion improvement, calcium intake, detox function, liver care, beauty, skin care, yin nourishing, sex drive and libido boost, etc. However, don’t simply trash its shell either. The reason for doing so is twofold: oyster shell recycling is crucial to marine ecosystems, plus it is of high medicinal value. Medicinally it is commonly used in combination with Long Gu (Dragon Bones) for the treatment of anxiety, insomnia, epilepsy, migraine, stroke, palpitations, night emission, and so on. As you can see now, oyster shell has comparable or better medicinal uses.
What are oyster shells medicinally?
As the name suggested, it mainly refers to the shells of Ostrea gigas Thunberg, Ostrea talienwhanensis Crosse, or Ostrea rivularis Gould. All of them are in the family Ostreidae and distributed along China’s coastal area. It can be collected all year round. And the following steps are to remove flesh, keep the shell, wash, and dry in the sun. And it is normally used crushed and raw/calcined.
Crassostrea gigas is in the shape of elongated flake, 10 to 50cm long, and 4 to 15cm wide. Dorsal seam and ventral seam are nearly parallel. Right shell is smaller and with thick scales arranged in layered or lamellar order. Lilac, white or brown outer surface is flat or with a few dents; porcelain white inner surface has no small teeth on sides of shell top. Left shell is sunken deep, and with thicker scales and small attachment surface on top. It is hard, white, odorless, slightly salty, and with layered cross sections.
Ostrea talienwhanensis is triangle and with splayed dorsiventral edges. Right shell is yellow outside and white inside and with loose wavy concentric scales. Left shell is with thick concentric scales, a couple of radial ribs from the top of the shell, recessed box-shaped inner surface, and small hinge surface.
Ostrea rivularis is round, oval, triangular, etc. Right shell is slightly uneven outside, with gray, purple, brown, yellow and other colors and concentric scales arranged in rings. Scales in young ones are thin and brittle. And they stack into layers after years of growing, with white inner surface and lavender edge in some.
80 to 95 % of chemical composition is calcium carbonate, calcium phosphate and calcium sulfate. Besides, they still contain magnesium, aluminum, silicon, and iron oxide. And another report says that ostrea talienwhanensis contains more than 90% calcium carbonate, 1.72% organic matter, and a small amount of magnesium, iron, silicates, sulfates, phosphates and chlorides. After the calcination, carbonate decomposes and produces calcium oxide and others while organic matter is destroyed.
Oyster shell health benefits
Modern medicine tends to believe that oysters contain a variety of nutrients that is necessary to the body. Clinically it is often combined with dragon bone since they has similar functions – tranquilization and liver-calming if used raw and astringency in the calcined form. More importantly, they supplement each other since oysters can also resolve hard lump while dragon bone has a better sedative action.
To better illustrate how it works, here we take its insomnia-healing property as an example. So, what is the difference between this herb and sleeping pills since both of them can help sleep disorder? To begin with, the former is a concept from traditional Chinese medicine while the latter comes from western medicine. And it doesn’t make any sense to compare them; then, they act at different mechanism – the source of the former’s healing power is its heavy nature, which traditionally is believed to calm agitated heart and spirit and get rid of timidity. And sleeping pills directly act on the nerve center to help sleep; furthermore, mineral and shell drugs have a wider range of application. But sleep pill only applies to temporary insomnia caused by cute psychological stress and physical illness or sleep disorders due to severe mental illness; finally, shell drugs work slowly and steadily, with no apparent side effects or addictive qualities. It can be tailored according to the needs of the individuals. Generally it is used as an assistance drug. Sleeping pills have definite and immediate curative effect. However, it has obvious side effects like dizziness, dry mouth, stomach discomfort, etc. And long-term use would lead to drug dependence and rebound phenomenon.
Modern pharmacological actions of oysters
1. Its flour showed astringency, sedation, detoxification, and anticonvulsant effects. Besides, it has significant analgesic effect in animal experiments;
2. Calcined oyster can significantly improve the resistance to experimental gastric ulcer;
3. Polysaccharides contained have hypolipidemic, anticoagulant, and antithrombotic effect;
4. Its acid extract in vivo has inhibition on poliovirus and thus lower mortality rate of the infected mice.
Sample oyster shell herbal remedies
According to the Chinese Materia Medica, it is salty in flavor and slightly cold in nature. And it acts on the meridians of liver and kidney. Basic functions are to calm the liver and suppress yang, tranquilize with its heavy nature, soften hardness to dissipate stagnation, and induce astringency. Main oyster shells uses and indications include vertigo, tinnitus, palpitation, insomnia, scrofula, goiter and tumor, abdominal mass, spontaneous sweating, night sweat, emission, uterine bleeding, and abnormal vaginal discharge. Recommended dosage is from 15 to 30 grams in decoction, pills or powder. And decocting before the rest herbs is required.
1. Gui Zhi Gan Cao Long Gu Mu Li Tang from Shang Han Lun (On Cold Damage). It is combined with Gui Zhi (Ramulus Cinnamomi), Gan Cao (Licorice Root), and dragon bones to treat fidget, palpitation, insomnia, dreaminess, etc.
2. Zhen Gan Xi Feng Tang from Yi Xue Zhong Zhong Can Xi Lu (Records of Heart-Felt Experiences in Medicine with Reference to the West). It is designed with dragon bone, Gui Ban (Fresh Water Turtle Shell), Bai Shao (White Peony Root), etc., to cure dizziness, irritability, and tinnitus.
3. Da Ding Feng Zhu from Wen Bing Tiao Bian (Detailed Analysis of Warm Diseases). It is formulated with Sheng Di Huang (Rehmannia), Gui Jia (tortoise shell), Bie Jia (Soft Turtle Shell), etc. to heal burning out of yin, deficient wind agitation, and limbs twitching due to chronic febrile diseases.
4. Xiao Luo Wan from Yi Xue Xin Wu (Medical Revelations). It is coupled with Zhe Bei Mu (Fritillaria Bulb), Xuan Shen (Scrophularia), etc. to cure subcutaneous nodule, scrofula, goiter and tumor, etc.
5. Mu Li San from Tai Ping Hui Min He Ji Ju Fang (Formulas of the Peaceful Benevolent Dispensary). It is used along with Ma Huang Gen (Ephedra root), Fu Xiao Mai (Triticum Aestivum L.), etc. to heal spontaneous perspiration and night sweats.
6. Jin Suo Gu Jing Wan from Yi Fang Ji Jie (Wang Ang and his Variorum of medical recipes). It is matched with Sha Yuan Zi (Flatstem Milkvetch Seed), Dragon bones, Qian Shi (Euryale Seed), etc. to treat nocturnal emission.
Oyster shell side effects and contraindications
Clinically no adverse reactions on oyster shells have been reported. But it is easy to cause constipation and indigestion in long-term use and high doses. According to Ben Cao Jing Ji Zhu (Explanation of Canon of Materia Medica), it loathes ephedra, Wu Zhu Yu (Evodia Fruit), and Xin Yi (Magnolia Flower). And according to the Shen Nong Ben Cao Jing Shu (Commentary on ‘Shen Nong’s Classic of the Materia Medica), oyster shell shouldn’t be used in the cases of deficient cold and spermatorrhea due to cold instead of fire caused by kidney deficiency.