Uploaded July 2024 | Updated September 2026, 2 weeks ago
“De Materia Medica,” written in the first century AD by Pedanius Dioscorides, a Greek physician in the Roman Army, would become the prime medical reference on which physicians would rely for some 15 centuries. It was a compendium of natural therapies such as the use of colchicum for gout, opium for pain and squill for heart problems, all of which would later prove to have scientific validity. Dioscorides also described small tablets made of clay from the Greek island of Lemnos, called “terra sigillata.” Mixed with the blood of a sacrificial goat these served as a “very powerful antidote against deadly poisons.” The sacrificial blood didn’t do anything as the Greeks themselves discovered. When the physician Galen visited the island a century later to witness how the tablets were prepared, blood had been replaced by wheat and barley, neither of which were likely to add to the efficacy.
And there likely was some efficacy. Clay is a complex mixture of various aluminum silicates that has the ability to absorb all sorts of substances, such as toxins produced by Shigella dysenteriae bacteria that cause the bloody diarrhea of dysentery. In the 16th century, physician Johannes Montanus in Silesia, now Poland, claimed to have discovered “Silesian terra sigillata” as a poison antidote. This was then widely promoted by Andreas Berthold, a former miner, who seized the idea as a business opportunity. Berthold was convinced of the clay’s wondrous properties and invited authorities to test it.
Wilhelm IV, prince of Hesse-Kassel, a state that was part of the Holy Roman Empire, took up the challenge and had his physicians conduct a trial with eight dogs that were given four different poisons. Unfortunately, the identity of these poisons was not recorded. Half the dogs were given the antidote and all survived, while the others died in agony. This can be regarded as an early example of a clinical trial! Wilhelm’s approval boosted the use of “Silesian terra sigillata” and it became a popular remedy against poison and diarrhea but fell out of favour when it proved to be ineffective against the bubonic plague.
Nevertheless, clay has continued to be used as a medicine, mostly against diarrhea, up to current times. Perhaps the best-known product is Kaopectate, originally made of a type of clay called kaolin and pectin, a soluble fiber that binds substances in the intestines and adds bulk to stool. When kaolin was found to have unacceptable amounts of arsenic and lead it was replaced by attapulgite, a different type of clay composed of magnesium aluminum silicate. Pectin was eliminated in favour of xanthan gum.
Recently another potential benefit of clay has emerged. Clay from Kisameet Bay in British Columbia, used for centuries by the Heiltsuk people as medicine, has proven to be effective against some drug-resistant bacteria. As more and more bacteria develop resistance to antibiotics, an ancient remedy may take on a new face.
“De Materia Medica,” written in the first century AD by Pedanius Dioscorides, a Greek physician in the Roman Army, would become the prime medical reference on which physicians would rely for some 15 centuries. It was a compendium of natural therapies such as the use of colchicum for gout, opium for pain and squill for heart problems, all of which would later prove to have scientific validity. Dioscorides also described small tablets made of clay from the Greek island of Lemnos, called “terra sigillata.” Mixed with the blood of a sacrificial goat these served as a “very powerful antidote against deadly poisons.” The sacrificial blood didn’t do anything as the Greeks themselves discovered. When the physician Galen visited the island a century later to witness how the tablets were prepared, blood had been replaced by wheat and barley, neither of which were likely to add to the efficacy.
And there likely was some efficacy. Clay is a complex mixture of various aluminum silicates that has the ability to absorb all sorts of substances, such as toxins produced by Shigella dysenteriae bacteria that cause the bloody diarrhea of dysentery. In the 16th century, physician Johannes Montanus in Silesia, now Poland, claimed to have discovered “Silesian terra sigillata” as a poison antidote. This was then widely promoted by Andreas Berthold, a former miner, who seized the idea as a business opportunity. Berthold was convinced of the clay’s wondrous properties and invited authorities to test it.
Wilhelm IV, prince of Hesse-Kassel, a state that was part of the Holy Roman Empire, took up the challenge and had his physicians conduct a trial with eight dogs that were given four different poisons. Unfortunately, the identity of these poisons was not recorded. Half the dogs were given the antidote and all survived, while the others died in agony. This can be regarded as an early example of a clinical trial! Wilhelm’s approval boosted the use of “Silesian terra sigillata” and it became a popular remedy against poison and diarrhea but fell out of favour when it proved to be ineffective against the bubonic plague.
Nevertheless, clay has continued to be used as a medicine, mostly against diarrhea, up to current times. Perhaps the best-known product is Kaopectate, originally made of a type of clay called kaolin and pectin, a soluble fiber that binds substances in the intestines and adds bulk to stool. When kaolin was found to have unacceptable amounts of arsenic and lead it was replaced by attapulgite, a different type of clay composed of magnesium aluminum silicate. Pectin was eliminated in favour of xanthan gum.
Recently another potential benefit of clay has emerged. Clay from Kisameet Bay in British Columbia, used for centuries by the Heiltsuk people as medicine, has proven to be effective against some drug-resistant bacteria. As more and more bacteria develop resistance to antibiotics, an ancient remedy may take on a new face.
