Medicinal clay

Renaissance period, and up to the present

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 inquiries, 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 the 6th of August) under the supervision of Christian monks and Turkish officials.

Modern investigation has shown that this was a clay similar to the modern ‘bentonite and/or Calcium Montmorillonite’.

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. Some practitioners insist that raw clay (as close to its original state as possible) has the best therapeutic effect.  This is because the raw clay also tends to contain a variety of micro-organisms that may contribute to healing.  Heating the clay may destroy those 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

Absorptive and adsorptive properties of clays


Clay demonstrates its absorptive properties by acting like a sponge; it draws various toxic substances into its internal multi-layered structure. The clay expands as the absorbed substance fills the spaces between its stacked silicate layers.


The clay’s mineral surfaces are negatively charged (i.e. they possess negative electrical charges), which attracts the positively charged toxins, such as the heavy metal ions. An exchange reaction then occurs; the clay swaps its ions for the heavy metal ions.

Detoxifying properties

The above processes contribute to the detoxifying properties that the medicinal clays exhibit. Also, see below.

Antibacterial properties

In a recent article in The Journal of Antimicrobial Chemotherapy, Haydel et al. studied iron-rich smectite and illite clay (Montmorillonite/Bentonite type of clay), and found that it was effective in killing bacteria in vitro. Authors report that the clay mineral,

“…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.”

In a more recent study funded by the National Institutes of Health, Williams, Haydel, et al. collected more than 20 different clay samples from around the world, including the bentonite-type clays, to investigate their antibacterial activities. The authors report that they have achieved promising results against MRSA superbug infections and disease. Also, see below.

Trace minerals

Clays contain massive amounts of trace minerals, necessary for good health. (It is common to see 60 different trace minerals and more in various clays.) This may explain many of the healing properties of clay. 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 different clays. For example, the amount of iron in various bentonite clays can vary from well below 1%, and up to 10%.

External Uses

Mud baths

This is perhaps the most common use of clay. Just about all health spas around the world use clay on a daily basis, and report many health benefits for bathers.

Skin infections

Many types of skin infections have been healed by the application of medicinal clay. Clay is used in many over the counter medicines for this purpose.

Buruli ulcer

This flesh-eating bacterial disease is found primarily in central and western Africa.

The World Health Organization (WHO) has described Buruli ulcer as “an emerging public health threat”. The disease is caused by the bacterium Mycobacterium ulcerans – which is related to the micro-organisms that also cause leprosy and tuberculosis. This bacterium produces a powerful toxin that causes necrotic lesions, and destroys the fatty tissues under the skin.

The toxin produced by the bacteria suppresses the immune system, so patients feel no pain, and there is no response from the body to the infection. The disease is quite similar to leprosy. The commonly accepted treatments, which include antibiotics and surgical intervention, have not been very effective.

(Antibiotics currently play little part in the treatment of this disease. Surgical excision can be effective if undertaken early, yet it leaves scars, and can be dangerous. Advanced disease may require prolonged treatment with extensive skin grafting. Thus, such treatment is expensive, and may be difficult to obtain in conditions where surgical doctors are a rare commodity.)

Two French medicinal clays have shown some remarkable results against this disease. Dr Lynda Williams and Dr Shelley Haydel of Arizona State University have been studying the effectiveness of these French green clays, which are mostly composed of minerals called smectite and illite. These clays exhibit significant antibacterial properties.

Use in bandages

In April 2008, the Naval Medical Research Center announced the successful use of a Kaolinite-derived aluminosilicate nanoparticle infusion in traditional gauze known commercially as “QuikClot Combat Gauze”.

Internal use

According to one theory,

“In the stomach, the negative electrical charges of tiny clay particles attract positively charged toxins from stomach fluids. This clumping prevents very small particles, such as toxic molecules, from passing through the walls of the intestines and entering the bloodstream.

The author notes further that, together with the clay, the toxins are then eliminated harmlessly out of the body through the kidneys or bowel.

There are many over the counter remedies for internal use that contain clay. The examples are the tablets such as 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.

Anti-diarrheal properties

In addition to the above clays, also Diosmectite clay is valued in medicine for its anti-diarrheal effects. Diosmectite is a type of a smectite aka Calcium Montmorillonite clay. It is described as a natural silicate of aluminium and magnesium, so it is magnesium-rich. It has strong adsorbent properties, so it’s used as an intestinal adsorbent in the treatment of several gastrointestinal diseases, including diarrhea. Basically, this seems to be another trade name for Bentonite-type clay.

According to a recent review article,

“Diosmectite reduces inflammation, modifies mucus rheologic properties, inhibits mucolysis, and adsorbs bacteria, bacterial enterotoxins, viruses and other potentially diarrheogenic substances.”

The same authors cite a number of studies showing that diosmectite is effective against diarrhea in children with mild-to-moderate acute symptoms. It reduces the duration of illness, and decreases the frequency of bowel motions after 2 days of treatment. No serious adverse effects have been observed.

In 2001, an Italian study examined the anti-diarrheal effects of a clay described as ‘smectite’, and also found positive results. The authors conclude that “smectite reduces the duration of diarrhea and prevents a prolonged course.” They also note that smectite clay increases intestinal barrier function.


Clays have proven to be effective against the Candida albicans infections. This is a type of a fungus (or yeast), which is a causal agent of opportunistic oral and genital infections. This type of infection, known as Candidiasis, also may enter the bloodstream, and become a systemic Candida infection.

In 1971, the influence of bentonite clay on the growth of Candida lipolytica has been studied by Maignan and Pareilleux. A clearly unfavorable effect of bentonite on Candida lipolytica growth was observed

Later on, the same authors have concluded that,

“The respiration of Candida lipolytica on n-tetradecane is decreased in the presence of bentonite.”

According to a 2009 study by Ghiaci et al., bentonite clays acts very strongly against Candida:

“The modified bentonite and Calcium Montmorillonite (Excelerite) with monolayer surfactant (BMS), was the best support, for immobilization.”

Heavy metal chelation

Chelation (purging) of heavy metals from the body has been a very effective way to treat many illnesses. Chelation therapy is the use of chelating agents to detoxify poisonous metal agents such as mercury, arsenic, and lead by converting them to a chemically inert form that can be excreted without further interaction with the body, and has been approved by the U.S. Food and Drug Administration in 1991.

Clay has proven to be a very effective chelating agent.

Oyanedel-Craver and Smith have studied absorption of four heavy metals (Pb, Cd, Zn and Hg) to 3 kinds of  clay. The overall conclusion of the study was that the organoclays studied have considerable capacity for heavy metal absorption.

Irritable bowel syndrome

“Beidellitic 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 and Calcium Montmorillonite clay have proven to show a very strong protective effect against Aflatoxicosis.

“The addition of bentonite or Calcium Montmorillonite (Excelerite) 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 hepato-nephroprotective agents against aflatoxicosis.”


“The addition of bentonite or Calcium Montmorillonite (Excelerite) was significantly effective in ameliorating the negative effect of aflatoxicosis on the percentage and mean of phagocytosis.”

Use by the NASA Space Program

The effects of weightlessness on human body were studied by NASA back 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.  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.”