The use of medicinal clay in folk medicine goes back to prehistoric times. Indigenous peoples around the world still use clay widely. Such uses include external application to the skin and geophagy. The first recorded use of medicinal clay goes back to ancient Mesopotamia.
A wide variety of clays are used for medicinal purposes—primarily for external applications, such as the clay baths in health spas (mud therapy). Among the clays most commonly used are kaolin and the smectite clays such as bentonite, montmorillonite, and Fuller's earth. However, their use is declining, and modern evidence-based medicine has ended the use of many types.
The first recorded use of medicinal clay is on Mesopotamian clay tablets around 2500 BC. Also, ancient Egyptians used clay. The Pharaohs’ physicians used the material as anti-inflammatory agents and antiseptics. It was used as a preservative for making mummies and is also reported that Cleopatra used clays to preserve her complexion. [1] [2]
The Ebers Papyrus of about 1550 BC is an important medical text from ancient Egypt which contains traditional advice going back many centuries earlier. It describes the use of ochre for a wide variety of ailments, including for intestinal problems. [3]
Lemnian Earth was extracted on the island of Lemnos starting from classical antiquity and continued to be in use until the 19th century, and was still listed in an important pharmacopoeia in 1848. [4] The clay was shaped into tablets with distinctive seals stamped into them, giving rise to its name terra sigillata —Latin for 'sealed earth'. The earliest mention of its application as a medicine appears in Dioscorides’ De Materia Medica, dated to approximately 50–70. [5] Many other classical authors, including Pliny and Galen, recommend Lemnian Earth for the treatment of poisonings, open wounds and other illnesses. [6] [7]
The other types of clay that were famous in antiquity were as follows.
All the above seem to have been bentonitic clays.
In medieval Persia, Avicenna (980–1037 CE), the 'Prince of Doctors', wrote about clay therapy in his numerous treatises.
Ibn al-Baitar (1197–1248), a Muslim scholar born at Malaga, Spain, and author of a famous work on pharmacology, discusses eight kinds of medicinal earth. [notes 1] The eight kinds are:
A French naturalist Pierre Belon (1517–1564) was interested in investigating Lemnian Earth. In 1543, he visited Constantinople where, after making enquiries, he encountered 18 types of different products marketed as Lemnian Earth. He then made a special journey to Lemnos, where he continued his investigation, and tried to find the source of the clay. He discovered that it was extracted only once a year under the supervision of Christian monks and Turkish officials.
In 1588 the English ethnographer and translator Thomas Harriot wrote in A Briefe and True Report of the New Found Land of Virginia that Algonquians of the mid–Atlantic region of North America treated various sores and wounds with wapeih, "very like to terra sigillata" that English surgeons and physicians found to be of the same kind "of vertue and more effectuall" than the contemporary European sort. [9]
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Clay gathered from its original source deposit is refined and processed in various ways by manufacturers. This can include heating or baking the clay, since the raw clay tends to contain a variety of microorganisms. [notes 2]
Too much processing, likewise, may reduce the clay's therapeutic potential. In particular, Mascolo et al. studied 'pharmaceutical grade clay' versus 'the natural and the commercial herbalist clay', and found an appreciable depletion of trace elements in the pharmaceutical grade clay. [11] On the other hand, certain clays are typically heated or cooked before use. [notes 3]
Medicinal clay is typically available in health food stores as a dry powder, or in jars in its liquid hydrated state – which is convenient for internal use. For external use, the clay may be added to the bath, or prepared in wet packs or poultices for application to specific parts of the body.
Often, warm packs are prepared; the heat opens up the pores of the skin, and helps the interaction of the clay with the body. [notes 4]
In the European health spas, the clay is prepared for use in a multitude of ways – depending on the traditions of a particular spa; typically it is mixed with peat and matured in special pools for a few months or even up to two years.
"The majority of spas … use artificial ponds where the natural ("virgin") clay is mixed with mineral, thermo-mineral, or sea water that issues in the vicinity of the spas or inside the spa buildings." [13]
Clays contain large amounts of trace minerals. It is common to see as many as 75 different trace minerals in Montmorillonite clays. [14] Specific trace minerals that various clays possess vary very widely. Also, the amount of any particular trace mineral in any specific clay varies a lot among clays from different locations. For example, the amount of iron in various bentonite clays can vary from 2.5 to 3%. [15]
Many skin conditions have been treated by the application of medicinal clay. Montmorillonite has shown its effectiveness in this area. [16] [17] [18] [19] It has also been used as a base ingredient for tissue engineering. [20] Clay is used in many dermatological over-the-counter remedies, such as in acne treatments though this information may not be specifically mentioned on the label.
There are many over-the-counter remedies for internal (oral) use that contained clay before discontinuation. Examples included Kaopectate (Upjohn), Rheaban (Leeming Div., Pfizer), and Diar-Aid (Thompson Medical Co.). The labels on all of these showed the active ingredient to be Attapulgite, each tablet containing 600 (or 750 mg) of this component along with inert materials or adjuvants. [21] However, since April 2003, attapulgite medication was discontinued due to lack of evidence according to the U.S. Food and Drug Administration. [22]
Kaolin was also used to treat cholera around the start of the 20th century. An early proponent was German physician Julius Stumpf. [23]
It has been used as a scientifically unsupported chelation treatment for heart disease and autism. [24] [25]
Bentonite has the ability to reduce the adverse effects of aflatoxicosis. [26]
Substances discontinued such as kaolin and attapulgite were formerly considered gastric demulcents and diarrhea medication, until official studies by the USFDA disproved these views. Clays are classified as excipients and their main side-effects are that of neutral excipients, which is to impair and slow down absorption of antibiotics, hormones and heart medication amongst others by coating the digestive tract [27] and this slowed down absorption can lead to increased toxicity of some medication (e.g. citrate salts) which can become toxic if not metabolized quickly enough, which is one contraindication of attapulgite. [28] Usual mild side-effects are nausea, slowed down absorption of nutrients from food (in excess dosage of medicinal clay) and constipation. It has been found that prolonged exposure to bentonite in humans can actually have harmful effects. [29]
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