Medicinal clay

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.

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.

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