About Clay

Please note, the following information is intended to inform people about bentonite clay. It outlines the differences between clay types, how to pick the best bentonite clay and why a good clay will work as it does. It is not aimed to replace the advice of your doctor.

One of the most powerful and gentle detoxifiers in my experience would have to be Bentonite clay. I now use a lot of this in my clinic for both internal and external removal of chemicals, heavy metals, infections and the like. I have seen it improve or resolve many things including poor bowel function, chronic ulcers, joint pain, odema, cracked feet and hands, skin rashes caused by chemicals and skin infections. To acheive these results it is essential that the right type of clay be used as all clays are not equal.

All clay is volcanic ash. As the lava flows down the side of the volcanic cone, the ash is blown high, oftentimes miles, into the sky. Slowly it settles to the ground, sometimes nearby, sometimes hundreds of miles away, and in extreme cases it can circumvent the globe.

Volcanic ash, clay, falls into seven separate and distinct family groups. Within these seven families there are thousands of different types of mineral compositions, each unique and serving vastly different purposes in our world.

Kaolin clays are best known for their uses in anti-diarrheal products such as Kaopectate. While it absorbs toxins and bacteria to a limited extent as do most clays, Kaolin clay acts primarily as a bulking agent and can be useful in cases of diarrhoea, although Diatomite and Bentonite will often be more effective.

Illite clay is known for its commercial applications. It is a green mineral clay found in marine settings. Some cosmeceutical companies use this industrial clay in their “mud” formulations due to it’s high content of long dormant microbials and other sea life residue. They are generally a non-swelling clay and aside from commercial uses, are known for topical use. I would not recommend taking Illites internally. Taking Illite internally can cause lung related reactions within 12 hours of ingestion.

Chlorite clays are know for their abrasive and cleansing properties. Clorox cleansing, scrubbing powder is a typical product made from this clay. Never use this caustic, abrasive clay on your body or internally.

Vermiculite clays are used for making china, pottery and other like applications such as porcelain finishes on metals. While Vermiculite is not recommended for use on the body, there is one company selling a USP grade Vermiculite for internal use. This is not an adsorbent, swelling clay, and has both a positive and negative charge. It is not recommeded for use as a health product.

Mixed group clays occur when a volcano spews ash from several different internal plate formations. It is not uncommon to find mixed group clay formation at many mines or quarries.

Lath-formed clay is yet another mixed form and it is typically used for fired bricks for construction. It is not suitable for use on or in the body.

Smectite clays comprise 99% of all clays used for health purposes today. Smectites are unique in that they swell while absorbing and adsorbing positive charged ions. It is the favoured clay for health and dietary use as well as for many industrial applications.

Smectites are more complicated in their structure than the majority of other clays and have a higher exchange capacity than the other six family groups of clay. They have a unique ability to adsorb and absorb toxins at a greater rate than any other clay type.

Within the Smectite family there are hundreds of different types of clays, each consisting of between 8 and 145 minerals. The most common sub family is Montmorillonite. Further along the Montmorillonite family tree are the various Bentonites.

How Clay Works

Bentonite is a natural inert clay that was formed from volcanic activity during the Cretaceous period approximately 100 million years ago. Long periods of repeated eruptions laid ash into the sea where it was chemically altered and consolidated into layers of clay. Over time the ground folded and lifted thrusting up the clay and silt to form deposits such as those found in the Black Hills and Big Horn mountains of Wyoming, USA. The term bentonite is generally applied to colloidal clay associated with the Cretaceous Benton shale found near Fort Benton – hence its name. Bentonite mining first began in 1888.


The first recorded use of the mineral known as “the clay of a thousand uses” was for making cosmetics. It then became used as a foundry sand bond in the 1920s followed soon after as a drilling mud. The uses have continued to expand into the fields of bleaching clay, animal feeds, pharmaceuticals, colloidal fillers for paints and inks, ceramics and in the motor industry for spark plugs and catalytic converters.

Bentonite clays are generally classified as sodium and calcium bentonites. When bentonite comes into contact with water, the atoms and molecules dissolve and ions with negative charges develop. These negative charges cause a mutual repulsion and thus a swelling within the clay structure. Calcium bentonites are known as low swelling bentonite due to their swell capacity being only 3 times their own dry volume.

The three sheet structure of a particle of bentonite.

In sodium based bentonites the clay can absorb nearly 5-6 times its dry weight in water. At full saturation it can swell up to 16 times its own dry volume. This makes it the superior clay where absorption (for example, of toxins, metals or dead tissue) is required.

Sodium bentonite consists of at least 90% montmorillonite and 10% other minerals; the most abundant being feldspar, selenite, quartz, calcite and gypsum. Montmorillonite is a three sheet structured mineral formed from several layers of tetrahedron and octahedron sheets. These sheets are parallel orientated and on the surface of the sheets there are atoms and molecules. It is this structure that gives the clay its ability to absorb and adsorb.

The words adsorption and adsorbtion are similar but their differences are fundamental to understanding how Bentonite clay minerals function and how healing clay works.

Adsorption describes the process by which the positively charged particles of other substances combine with the negatively charged particles on the outer surface of the clay molecule. This process could be likened to things being stuck to the outside of the clay a bit like velcro.

To understand this from a more scientific perspective, imagine the structure of the clay molecule to be similar to a stack of playing cards with spaces in between the cards (like the diagram in Figure 2). When the clay is hydrated, the spaces between the cards fill up with water which creates a strong negative charge in the hydrated clay. The clay molecule has unsatisfied ionic bonds around its edges when activated by the water and naturally seeks to satisfy (fill) those bonds. For the clay’s unsatisfied bonds to become full, it must come into contact with another substance with unsatisfied bonds that carry the opposite electrical (ionic) charge to the clay. When the two oppositely charged substances meet, the ions held on the outer surface of the clay particle are exchanged with the ions held on the outside surface of the other substance.

Absorption is a slower and more complex process. This process could be likened to the clay acting as a sponge. The Bentonite clay particle will draw substances with the opposite charge to itself into its internal structure when the clay is in a liquid medium such as water. Toxins that have the opposite charge to the clay can be pulled into and held inside the clay structure. The more substances that are pulled into the clay’s inner structure, the more the clay expands and swells. This is the primary reason why absorptive clays are labeled as mobile layered or expandable clays. Once a substance is absorbed into the clay, it generally stays there.

All absorbent clays have a charge on their inner layers. This means that charged ions sit between the layers of the clay particle surrounded by water molecules. The clay expands as foreign substances are absorbed and fill the spaces between the clay particle’s stacked layers. Absorbent clay will absorb positively charged toxins, bacteria and impurities. Anything with a negative charge is not affected by the clay as a general rule, although it appears that the alkaline pH of the clay can have inhibitory effects on some fungi and negatively charge bacteria species.

Clay Quality

The cation exchange capacity (CEC) is the measure of a clay’s ability to absorb and the higher the CEC, the better the clay will be at drawing and holding waste. A good bentonite clay should have at least an 80-90 CEC. Purely Earth’s clay has a CEC that is significantly higher at 104 and it is unusual to find a clay with a CEC this high. To our knowledge, Purely Earth Clay has the highest CEC of all the clays available in New Zealand and possibly world-wide.

It is important that the clay is untreated. Many bentonite clays are acid leached, heated or tampered with in some way. If being used in or on the body, it is essential to use a food grade clay because this will have been tested for heavy metals and other contaminants. Sodium bentonite tends to be less drying to the skin than calcium bentonite, and because it has a higher absorption ability it tends to be a better “sink” for toxins.

A quality clay should be milled to a 44 micron particle size and should have a low contaminant level. There are a number of clays around that contain a significant amount of feld spar, quartz or other mineral compounds and contaminants. A quality bentonite clay should be over 90% pure bentonite and should meet food grade standards. Purely Earth Clay fits all of these specs.

Both food grade calcium and sodium bentonite may be used internally. Sodium bentonite is the more active of the two clay types. Improved bowel frequency, better stool formation and decreased gas and odour are some of the benefits experienced by most people who use our clay internally.

Generally, the higher the CEC rating, the finer the grade and the higher the swelling capacity of the clay is, the more effective it will be. Be wary of clays that do not have a high CEC rating, that are not food grade, are coarse or multi coloured, or where the supplier can’t give you the mineral composition, pH, particle size and CEC rating details.

Purely Earth’s Clay is one the best quality clays in the world. It meets Australian Food Safety Standards and carries a Food Chemical Codex IV certification.

History of Healing Clay

The names Bentonite and Montmorillonite are sometimes used interchangeably to refer to edible Bentonite clays belonging to the smectite family of clays. These clays were formed from volcanic activity millions of years ago and are principally volcanic ash.

Bentonite clays are sometimes referred to as “living clays” as they principally consist of minerals that contribute to the production of enzymes in all living organisms. They are the preferred clays to be ingested by humans, animals, and plants and for incorporating into soil.

Healing clay may be a new concept to some of us, but it has been used for thousands of years. Long before recorded history, humans have used healing clays externally and internally to cure illnesses, sustain life and promote general health. Ancient tribes of the high Andes, central Africa and the Aborigines of Australia used clay as a dietary staple, a supplement and for healing purposes.

In the second century A.D., Galen, the famous Greek philosopher and physician, was the first to record the use of clay by sick or injured animals. He later recorded numerous cases of the internal and external uses of clay in his treatise on clay therapy. In ancient Arabia, Avicena, the “Prince of Doctors”, taught hundreds of his students about clay therapy.

Dioscorides, a Greek who was considered the engineer of medicine for the Roman Empire, attributed “God-like Intelligence” to the properties exhibited by clay used for therapeutic purposes.

The Essenes (authors of the dead Sea Scrolls) used clay for the natural healing of a wide variety of illnesses and injuries, and there are numerous Biblical references to the healing powers of clay.

The many benefits of clay were recognized by the Amargosians (who preceded the Aztecs) and the natives of Mexico and South America. North American Indians used clay for food, body purification, healing, in ceremonial events and for trading with other tribes.

Early French cultures used clay for nutrition and medicinal purposes and also as a trading medium. They touted the clay’s healing effect on gum diseases, ulcers, rashes, dysentery, hemorrhoids, infected wounds and bites.

The 19th century German naturopath, Sebastian Kneipp, and fellow naturalist Adolph Just, accorded clay therapy a prominent position in their arsenal of holistic medicine due to the tremendous results they achieved using it.

Early in the 20th century, Julius Stump, a renowned Berlin Physician, successfully used clay therapy to treat Asiatic cholera. A contemporary, Dr. Meyer Camberg, used green clay to neutralize arsenic poisoning. During the 1st World War, German physicians offered clay therapy as a solution to the food poisoning, dysentery, diarrhea, and wound infection that was rampant among troops on both sides, greatly reducing mortality rates.

During the First World War, the Russian soldiers received 200 grams of clay along with their rations and it was added to mustard in several French regiments, who remained free of the dysentery which ravaged nearby regiments.

Modern man is also beginning to appreciate the miraculous healing properties of Bentonite clay. Russian scientists used clay to protect their bodies from radiation when working with nuclear material. Because it adsorbs radiation so well, Bentonite clay was the material chosen to dump into the Chernobyl reactors after the nuclear meltdown there. Today, osteopaths, and other health professionals that include alternative medicine as a part of their practice, are increasingly recommending Bentonite clay to their patients for detoxification and to address other illnesses and injuries.

Debunking Erroneous Beliefs About Bentonite Clay

Before healing clays became so popular, there was very little information on the internet regarding these all-natural, drug-free, alternative healing modalities. Since the popularity of Bentonite clays has increased, misconceptions about how they work have become rampant. Here are some answers to some common questions:

  1. Does taking clay internally absorb nutrients, vitamins and minerals from daily supplements and foods you eat? Bentonite clay cleanses the colon by pulling out old putrefied fecal matter and mucoid plaque buildup that is blocking the absorption of vitamins, minerals, supplements and nutrition from the foods we eat. In this way, it generally improves the uptake of nutrients. Energy levels have been known to increase in 1-3 days, depending on the state of the individual. As a safe guard it is advised to avoid taking clay within 2 hours of consuming medications and food because there is some chance that it may absorb positively charged components from these.
  2. Does Bentonite clay absorb all the good flora bacteria in the digestive tract? According to Raymond Dextreit, the author of Earth Cures, “Clay is incomparable for maintaining or reestablishing a good normal flora, for it favors the development of useful ferments, while opposing the growth of pathogenic bacilli.” In our experience, the clay helps to clean up bio-films in the gut that contain pathogenic bacteria and in doing so creates a better space for the good bugs to grow.
  3. Is the aluminum in clay dangerous? Aluminum is part of the structural make up of all clays. It is partly the way the aluminium is built into the clay structure that gives the clay its high negative charge. The aluminum in Bentonite clay is in a safe silicate form, not the form used in foils, windows, cookware, cosmetics and the like. The many trace minerals in Bentonite clay are fused together into a super compound structure known as a clay particle, most of which cannot be broken down or absorbed by your body. We have done many mineral tests for people taking the clay and have not seen aluminium levels increase as a result of clay use.
  4. Is clay a dietary supplement, like a vitamin? Though very small amounts of the dominant minerals (i.e. calcium, magnesium, sodium and potassium) in clays might be exchanged in the adsorption ionic exchange layer, they are not sufficient to meet daily supplement requirements.

Resources: Raymond Dextreit, Earth Cures (Citadel, 2000); Michel Abehsera, The Healing Clay (Lyle Stuart, 1986); Ran Knishinsky, The Clay Cure (Healing Arts Press, 1998) ; Perry A, Living Clay.

© Self Heal Clinic and Purely Earth Ltd. This document may be copied and used as a patient handout in its entirety but is not to be replicated on any other websites or publishing media either in full or part without our permission.