The use of medicinal clay in folk medicine goes back to prehistoric times. Indigenous peoples around the world still use clay widely, which is related to 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.
- 1 Questions of nomenclature
- 2 Animal geophagy
- 3 Preparation of clay
- 4 Medicinal properties of clay in modern research
- 4.1 Antibacterial properties
- 4.2 Trace minerals
- 4.3 External use
- 4.4 Internal use
- 5 Common medicinal clays
- 6 See also
- 7 Notes
- 8 References
- 9 Further reading
- 10 External links
Questions of nomenclature
There are considerable problems with the exact nomenclature of various clays. No clay deposit is exactly the same and, typically, mineral clays are mixed in various proportions.
The overwhelming majority of clay mined commercially is for industrial uses, such as construction and oil drilling. Thus, the precise classification and chemical composition of these clays are somewhat secondary to their intended use. Bentonite clay, montmorillonite clay, and Fuller's earth are similar.
Sodium bentonite/calcium bentonite are the most commonly used medicinal clays today (sodium bentonite for external use, calcium bentonite for internal use), although there is no precise definition of what this term means. In fact, typically, "bentonite" refers to a wide spectrum of clays with a wide array of properties (such as a variety of colours). In alternative medicine, often this is used as more or less a catch-all term for medicinal clays.
Another such term is "montmorillonite", which is often interchangeable with "bentonite". Bentonite is included in the United States Pharmacopeia, and the USP-grade bentonite is widely used in various pharmaceutical and cosmetic preparations as a compounding and suspending agent. It is not entirely clear where the source of USP-grade bentonite is located; it may be a mixture of various bentonites.
Most of the nomenclature currently used is discussed in a 2005 World Health Organization report BENTONITE, KAOLIN, AND. SELECTED CLAY MINERALS, as well as an entire section of the USGS website Minerals Information: Clays
Animals both in the wild and domesticated consume different types of earth and clay. This type of geophagy has been documented in "many species of mammals, birds, reptiles, butterflies and isopods, especially among herbivores."
In particular, in Peru, Amazonian rainforest parrots of some 21 species gather at certain sites on cliff faces where bare soil is exposed, and eat the clayish soil. The soil they eat is specific, since they focus on a rather narrow band of exposed soil. What they eat is mostly clay that is less than 0.2 millimetre in particle diameter.
Some scholars believe that prehistoric ancestors such as Homo erectus and Homo neanderthalensis used ochres to cure wounds as well as paint caves. Ochres are a mixture of clay and iron hydroxides.
"The oldest evidence of geophagy practiced by humans comes from the prehistoric site at Kalambo Falls on the border between Zambia and Tanzania (Root-Bernstein & Root-Bernstein, 2000)." Here, a calcium-rich white clay was found alongside the bones of Homo habilis (the immediate predecessor of Homo sapiens).
Use by aboriginal peoples
Clay is used widely by indigenous peoples around the world, and is related to geophagy.
Ancient Egypt and Mesopotamia
The first recorded use of medicinal clay is on Mesopotamian clay tablets around 2500 B.C. 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.
The Ebers Papyrus of about 1550 BC (but containing the tradition going back many centuries earlier) is an important medical text from ancient Egypt. It describes the use of ochre for a wide variety of complaints, including for intestinal problems, as well as for various eye complaints.
This was a clay used in Classical Antiquity. It was mined on the island of Lemnos. Its use continued until the 19th century, as it was still listed in an important pharmacopoeia in 1848 (the deposits may have been exhausted by then).
if rubbed under the eyes, it moderates pain and watering from the same, and prevents the flow from the lachrymal ducts. In cases of haemorrhage it should be administered with vinegar. It is used against complaints of the spleen and kidneys, copious menstruation, also against poisons, and wounds caused by serpents.
Lemnian clay was shaped into tablets, or little cakes, and then distinctive seals were stamped into them, giving rise to its name terra sigillata—Latin for 'sealed earth'. Dioscorides also commented upon the use of terra sigillata.
Another physician famous in antiquity, Galen, recorded numerous cases of the internal and external uses of this clay in his treatise on clay therapy.
Galen... used as one of his means for curing injuries, festering wounds, and inflammations terra sigillata, a medicinal red clay compressed into round cakes and stamped with the image of the goddess Diana. This clay, which came from the island of Lemnos, was known throughout the classical world.
Other clays used in classical times
The other types of clay that were famous in antiquity were as follows.
- Terra chia, Terra cymolia (Cimolean earth): these were both white earths and considered of great value.
- Samian earth: Pliny in c. 50 AD (Nat. Hist.) details two distinct varieties, colyrium - an eye salve, and aster, which was used as a soap as well as in medicines.
- Terra sigillata strigoniensis (Strigian earth, derived from Silesia) - this clay, yellow in colour, appears to have been famous later in medieval times.
All the above seem to have been bentonitic clays.
- The earth which did not stain the hands was known as rubrica.
In medieval Persia, Avicenna (980-1037 CE), the 'Prince of Doctors', wrote about clay therapy in his numerous treatises.
- the terra sigillata,
- Egyptian earth,
- Samian earth,
- earth of Chios,
- Cimolean earth or pure clay (cimolite), soft earth, called al-hurr, green in color like verdigris, is smoked together with almond bark to serve as food when it will turn red and assume a good flavor; it is but rarely eaten without being smoked—also called 'Argentiera',
- earth of vines called ampelitis (Pliny XXXV, 56) or pharmakitis from Seleucia in Syria,
- Armenian earth (also known as the Armenian bole), salutary in cases of bubonic plague, being administered both externally and internally,
- earth of Nishapur.
A French naturalist Pierre Belon (1517–1564) was interested in investigating the mystery of the Lemnian clay. In 1543, he visited Constantinople where, after making enquiries, he encountered 18 types of different products marketed as Lemnian Earth (he was concerned about possible counterfeits).
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 (on 6 August) under the supervision of Christian monks and Turkish officials.
Preparation of clay
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 micro-organisms
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. On the other hand, certain clays are typically heated or cooked before use.
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.
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."
Medicinal properties of clay in modern research
"...exhibits bactericidal activity against E. coli, ESBL [Extended-Spectrum Beta-Lactamases] E. coli, S. enterica serovar Typhimurium, P. aeruginosa, and M. marinum, and significantly reduces growth of S. aureus, PRSA, MRSA, and nonpathogenic M. smegmatis approximately 1,000-fold compared to cultures grown without added mineral products."
Falkinham et al. studied the antibiotic and antimicrobial activity of red clays from the Kingdom of Jordan (Jordan's Red Soil). The authors conclude that the antibiotic activity of Jordan's red clays is likely due to the proliferation of antibiotic-producing bacteria, that is induced by the clay.
Clays contain large amounts of trace minerals. It is common to see as many as 75 different trace minerals in Montmorillonite clays. 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 well below 1%, and up to 10%.
Mud baths are perhaps the most common use of clay and are commonly used at all health spas.
Many types of skin conditions have been treated by the application of medicinal clay. Montmorillonite has shown its effectiveness in this area. It has also been used as a base ingredient for tissue engineering. Clay is used in many dermatological over-the-counter remedies, such as in acne treatments (this information may not be mentioned on the label specifically).
Use in bandages
In April 2008, the Naval Medical Research Center announced the successful use of an updated Kaolinite-derived aluminosilicate nanoparticles infusion in traditional gauze known commercially as "QuikClot Combat Gauze". The earlier formulation had significant problems with heat generation in the wounds.
There are many over the counter remedies for internal use that contained clay before discontinuation. Examples include 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. However, since April 2003, attapulgite medication was discontinued due to lack of evidence according to the U.S. Foods and Drugs Administration.
Numerous medicines also use Kaolinite clay, which has long been a traditional remedy to soothe an upset stomach. Also, Kaolin is or has been used as the active substance in liquid anti-diarrhea medicines such as Kaomagma. Such medicines were changed away from aluminium substances due to a scare over Alzheimer's disease, but have since changed back to compounds containing aluminum as they are most effective.
Clays have been effective against the Candida albicans (in vitro), a yeast which is a causal agent of opportunistic oral and genital infections and rarely more serious infections. The influence of bentonite clay on the growth of Candida lipolytica has been studied. An unfavorable effect of bentonite on Candida lipolytica growth in vitro was observed. According to a 2009 study, bentonite clay acts very strongly against Candida.
Heavy metal chelation
Oyanedel-Craver and Smith have studied sorption of four heavy metals (Pb, Cd, Zn and Hg) to 3 kinds of bentonite clay. The overall conclusion of the study was that the organoclays studied have considerable capacity for heavy metal sorption.
Irritable bowel syndrome
"[B]eidellitic montmorillonite is efficient for C-IBS patients (suffering from constipation-predominant irritable bowel syndrome)..."
Aflatoxins are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus. Aflatoxins are toxic and among the most carcinogenic substances known. They cause Aflatoxicosis, which can afflict both animals and humans.
Bentonite clay has proven to show a very strong protective effect against Aflatoxicosis.
"The addition of bentonite or HSCAS [hydrated sodium calcium aluminosilicate] to the AF-contaminated diet diminished most of the deleterious effects of the aflatoxin. Pathological examinations of liver and kidney proved that both bentonite and HSCAS were hepatonephroprotective agents against aflatoxicosis."
Also, regarding chickens:
"The addition of sodium bentonite was significantly effective in ameliorating the negative effect of aflatoxicosis on the percentage and mean of phagocytosis."
Conversely, it has been found that prolonged exposure to bentonite in humans can actually have harmful effects.
Use by the NASA space program
The effects of weightlessness on human body were studied by NASA in the 1960s. Experiments demonstrated that weightlessness leads to a rapid bone depletion, so various remedies were sought to counter that. A number of pharmaceutical companies were asked to develop calcium supplements, but apparently none of them were as effective as clay. The special clay that was used in this case was Terramin, a reddish clay found in California. Dr. Benjamin Ershoff of the California Polytechnic Institute demonstrated that the consumption of clay counters the effects of weightlessness. He reported that "the calcium in clay ...is absorbed more efficiently ... [clay] contains some factor or factors other than calcium which promotes improved calcium utilization and/or bone formation." He added, "Little or no benefit was noted when calcium alone was added to the diet."
Side effects and USFDA disproval of oral intake effectiveness
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  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. Usual mild side-effects are nausea, slowed down absorption of nutrients from food (in excess dosage of medicinal clay) and constipation.
Common medicinal clays
- Bentonite-type clay has been used to treat infections, indigestion, and other medical problems by both applying wet clay topically to the skin as a poultice, and by ingesting it. Bentonite has been prescribed as a bulk laxative, and it is also used as a base for many dermatologic formulas. Dermatologically, it is used as part of a treatment for pruritis. Also, bentonite can be used as a therapeutic face pack for the treatment of acne/oily skin. Clearasil, an acne cream, uses bentonite as an agent to absorb excess sebum, clearing pores.
- Montmorillonite is the main constituent of bentonite.
- Attapulgite or palygorskite is a very absorbent clay, somewhat similar to bentonite. When used in medicine, it physically binds to acids and toxic substances in the stomach and digestive tract. For this reason, it has been used in several anti-diarrheal medications.
- Kaolin is not as absorbent as most clays used medicinally (it has a low shrink-swell capacity). Also, it has a low cation exchange capacity. This clay is also known as 'white cosmetic clay'. Clay, in the form of kaolin, was a common ingredient in western medicines such as Kaopectate Rolaids and Maalox, but is no longer present in them nor in similar preparations, as it is considered ineffective by the USFDA.
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