Clay minerals and their beneficial effects upon human health. A review

Abstract

This work examines the beneficial effects for human health of clay minerals, describing their use in pharmaceutical formulations, spas and aesthetic medicine. Their therapeutic action as active principles in pharmaceutical formulations orally administered (gastrointestinal protectors, laxatives, antidiarrhoeaics) or for topical applications (dermatological protectors and cosmetics) is described. Their use as excipients and their influence in the bioavailability of the organic active principle is also described, both in the liberation process and in its possible degradation effect. Among their uses in spas, clay minerals therapeutic activity, in geotherapy, pelotherapy and paramuds is commented upon. Moreover, the applications of the clay minerals in aesthetic medicine (to clean and moisturise the skin and to combat compact lipodystrophies, acne and cellulite) are also described.

Introduction

The use of minerals for medicinal purposes is almost as old as mankind itself. Minerals have been used for curative ends since Prehistory. There are indications that Homo Erectus and H. Neanderthalensis used ochres mixed with water and different types of muds in order to cure wounds, soothe irritations, as a method of cleansing the skin, etc. This might have been due to their mimicking animals, many of which instinctively use minerals for the above purposes. The use of medicinal earths in Mesopotamia and Ancient Egypt has also been proven. The use of Nubian earth as an anti-inflammatory or the use of mud materials for mummification of cadavers can be cited as examples Bech, 1987, Robertson, 1996, Veniale, 1997. In the Ancient Greek period, mud materials (Lemnos Earth) were used as antiseptic cataplasms to cure skin afflictions, as cicatrisers or as a cure for snake bites. Both Hippocrates and Aristotle, among others, produced classifications of medicinal earths. Most of these materials are clays, given different names depending on their origins or on the differences in their mineralogical composition and properties. For example, Terra Samia, T. Sigillata, T. Lemnia, T. Cimolia, T. Sonóptica, T. Eretria, T. Negra, etc. Bech, 1996, Giammatteo et al., 1997. Furthermore, Cleopatra, Queen of Egypt, used muds from the Dead Sea for cosmetic purposes and Marco Polo describes how in his travels he saw Muslim pilgrims cure fevers by the ingestion of “pink earth” (Veniale, 1996).

The first written reference known to exist upon the use of “stones” and a description of their curative powers dates from Roman times, 60 BC, and is in Dioscorides' “De Materia Medica”. This book also has a final section dealing with minerals and chemical substances used in Pharmacy. Moreover, in his “Natural History” Pliny the Elder describes the use of clays, especially those to be found around Naples (volcanic muds) for stomach and intestinal ailments. During the Middle Ages Avicena and Averroes in the 9th and 10th Centuries classified and encouraged the use of medicinal muds, and Galeno, Arabic doctor, used clays for the malaria, Bech, 1987, Veniale, 1999. Later, “Lapidarios”, works which partially dealt with the use of minerals from a therapeutic perspective, would appear, among which figures the famous “Lapidarios” of the Spanish King, Alfonso the Wise (1250). The first “Lapidario”, which has been completely kept, is a translation into Spanish by Yhuda Mosca and Garci Pérez from the Abolays' arabic book which Abolays himself had previously translated from Chaldean into Arabic although its original source is not known (Brey Mariño, 1982).

During the Renaissance Pharmacopoeia appeared. These were texts, which classify, among other drugs, the different minerals for medicinal uses and regulations upon the same, such as official codes, which had to be obligatorily followed in order to produce medicines. Their appearance coincided with the first mineralogical classifications. In the 17th Century, the first Scientific Academies were founded and one aspect of their work was to document the advances of Mineralogy with respect to medico-pharmaceutical matters, thus producing various entries in the pharmacopoeias. The development of Crystallography and Mineralogy in the 18th and early 19th Centuries was of great importance in increasing the knowledge of the raw mineral materials used in pharmacy and cosmetics. However, the development of the Chemistry in the early 20th Century, which enabled numerous minerals to be obtained through synthesis, had a negative effect upon the use of minerals for therapeutic uses, due to the use of “synthetic mineral-like” Bech, 1987, Galán et al., 1985.

At present, the minerals which are used for therapeutic purposes are basically clay minerals, given the difficulty and the cost involved in synthesising them industrially. An exception is a synthetic equivalent of hectorite named “Laponite S” provided by Laporte (NL) which is used as a gelifying material in cosmetic. Clay minerals are used in pharmaceutical formulations (as active principles or excipients), in spas and in aesthetic medicine.