Kaolin (Chi Shi Zhi)

HalloysiteIf you have ever seen pink kaolin clay, also known as Chi Shi Zhi in China, probably you would be interested in its look, right? Widely as it is used in many Chinese herbal remedies, it is not an herb at all. On the contrary, it is a block-shaped edible clay mineral. Because of its pink skin, kaolin looks pretty attractive. However, as an herbalist what really matters is its benefits rather than how it looks, nicely or uglily.

What is kaolin?

Also known as Halloysite, Kaolinite, or China clay, it refers to a layered hydrous aluminum silicate. It is named because initially it was introduced from Gaoling (Kao-ling), a small town close to Jingdezhen, Jiangxi province, China. Besides, white kaolin clay is also found in some places in Africa and the United States, like Georgia.

The impurities need to be removed after excavation in the medicinal kaolin. It is a kind of dioctahedral phyllosilicate clay, in irregular lumps and in colors of pink, red to fuchsia, and sometimes with red/white patterns. It is soft, fragile, absorbent, tasteless, earthy, and with wax-like luster on the cross section. In addition, there is no sandy feeling at all when eating kaolin clay.

What is kaolin used for?

TCM regards kaolin as sweet, astringent, acid, warm, and non-toxic in nature. And it covers four meridians, such as spleen, stomach, heart, and large intestine. Its dominating functions are to astringe intestine to stop diarrhea, stop bleeding, astringe dampness, and promote tissue regeneration. Prime kaolin uses and indications are chronic diarrhea, lingering dysentery, proctoptosis due to prolonged dysentery, having blood in stool, nocturnal emission, metrorrhagia and metrostaxis, leucorrhea, chronic unhealing ulceration, eczema, and traumatic bleeding. Usual dosage is from 9 to 12 grams, normally in decoction, powder, or pills. And in the case of external use, appropriate amount of kaolin clay powder will be just fine.

Chemical composition

Its main component is hydrated aluminum silicate, and it also comes with considerable substances such as iron oxide, which is composed of 42.93% silicon, 36.58% aluminum, 4.85% iron oxide and manganese, 0.94% magnesium and calcium, and 14.75% water.

Pharmacologic action

Antidiarrheal effect. Kaolin contains large amounts of hydrated aluminum silicate, which can absorb toxins in the digestive tracts, such as phosphorus, mercury, bacterial toxins, abnormal fermentation products, and inflammatory exudate. What’s more, it is able to cover the intestinal mucosa in order to reduce the stimulation to gastrointestinal tract, which thus presents adsorptive antidiarrheal effect.

Hemostasis. Experiments showed that kaolin mixture can shorten clotting time and bleeding time significantly, which creates a significant difference (P <0.001) compared to rhubarb and saline control groups.

Chinese herbal formulas containing kaolin

Chi Shi Zhi is a common herbal ingredient in Chinese herbal remedies, especially for diarrhea treatments. The following are the typical ones for your reference.

Tao Hua Tang

Tao Hua Tang comes from Shang Han Lun (On Cold Damage). It is the classic formula for treating bloody purulent stool in shaoyin disease. Other main herbs include Gan Jiang (Dried Ginger Root) and Jing Mi (non-glutinous rice).

Chi Shi Zhi Yu Yu Liang Tang

This formula also comes from Shang Han Lun (On Cold Damage). It is exclusively formulated for unceasing diarrhea due to deficiency in the lower energizer. The other herb is Yu Yu Liang (Limonitum).

Chi Shi Zhi San

From Xiao Er Yao Zheng Zhi Jue (Key to Syndrome Identification and Treatment of Diseases in Infants), this prescription is mainly for treatment of rectal prolapse after infantile diarrhea. The other herb is Fu Long Gan (Terra Flava).

Chi Shi Zhi Wan

From Jin Gui Yao Lue (Essential Prescriptions of theGolden Coffer), this recipe is chest pain radiating to the back or back pain radiating to the chest. Other primary herbs include Shu Jiao (Hua Jiao, Pericarpium Zanthoxyli), Wu Tou (Radix Aconiti Carmichaeli), Fu Zi (Prepared Aconite Root), and Gan Jiang (Dried Ginger Root).

Zi Xue Tang

Zi Xue Tang comes from Tai Ping Hui Min He Ji Ju Fang (Formulas of the Peaceful Benevolent Dispensary). It is primarily used for women of internal lesion caused by overexertion, failure of regulating menstruation due to Chong-Ren debility, and profuse uterine bleeding, in fresh blood or in blood stasis.

Potential kaolin side effects and contraindications

Non-toxic as Kaolin (Chi Shi Zhi) is in TCM theory, it should not be used in a few special occasions, especially in those with syndrome of damp-heat. What’s more, please use with extra care in cases of pregnant woman too.

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