BENTONITE CLAY – Benefits and mechanism of action
Healing practices of ancient cultures, as well as modern society, have depended on clay minerals with powerful adsorptive and absorptive properties to treat a variety of topical maladies.
Most of the healing clays described in the literature are bentonites. However, bentonite is not a mineral but is a generic term for rocks derived from ‘altered volcanic ash beds’. The ash is a layered sedimentary deposit that accumulates during volcanic eruptions. This ash produces mostly disordered solids but glassy particles formed by rapid quenching (cooling) of magma when the liquid material is thrown into the atmosphere.
Most uses and research emphasis on healing clays has focused on the physical characteristics of clay minerals that benefit digestion or protect and cleanse the skin.
Adsorption is the process of attraction, binding, and accumulation of molecules or particles to a solid surface in a condensed layer.
Absorption results when a substance diffuses or penetrates into a liquid or solid forming a transition zone or layer, often with a new composition, adjacent the substrate.
The high adsorption and absorption capacities, cation exchange capacity, as well as the extremely fine particle size of certain clays, e.g. smectites (expandable clay minerals) and kaolin group minerals are important reasons why these minerals are used to remove oils, secretions, toxins, and contaminants from the skin. By adsorbing and absorbing moisture and impurities from the skin, the clays also serve to cleanse and refresh the skin surface and to aid in the healing of topical blemishes, the major selling point for many cosmetics.
The ingestion of dried clay minerals or a clay suspension is commonly used as a source of dietary elements, as a detoxifying agent, and as an allopathic treatment of gastrointestinal illnesses and acute and chronic diarrhea. For example in Ghana, the iron, copper, calcium, zinc, and manganese consumed in clays were in the range of 2 to 15 percent of recommended dietary allowances and it was concluded that moderate ingestion of clays lacking high cation-exchange capacities could serve as a nutritional supplement for these essential elements.
In the acidic environment of the stomach, the clay minerals could bind to positively charged toxins and serve as detoxifying agents to reduce bioavailability interfering with gastrointestinal absorption of the toxin .
Over-the-counter pharmaceuticals that originally contained kaolinite, attapulgite, or clay-like substances (i.e. Kaopectate®) represent classic examples of the use of clay minerals by human populations to treat diarrhea and intestinal illnesses and soothe gastrointestinal ailments. Kaolinite has many medically beneficial attributes primarily related to its ability to adsorb lipids, proteins, bacteria, and and viruses.
Clay minerals are ubiquitous in nature and their adsorptive and absorptive capabilities have been exploited in a variety of cosmetics and pharmaceutical formulations. Traditionally, clay minerals are mixed with water for various periods of time (days to years) to form clay gels or pastes that can be applied externally for cosmetic or skin protective purposes.
The adsorptive and absorptive properties of clay minerals have historically been the driving force behind the traditional use of healing and therapeutic clays. Initially, negatively-charged interlayer sites of clays will absorb positively-charged substances to their extensive surface area. Over time, many clay minerals may absorb substances in between the stacked silicate layers of the mineral, allowing for expansion and swelling or contraction. While the physical adsorption of water and organic matter is the most common attribute of healing clays, the geochemical mechanisms controlling antibacterial properties of clays have received significantly less attention.