Ancient clay remedy ‘secret to modern gut health’

Researchers have found that a 2,500-year-old clay from the Greek island of Lemnos could boost the microbiome

An ancient medicinal clay could boost our modern-day gut health, researchers say.

Experts analysed Lemnian earth (LE), a grey-to-yellow or red clay obtained from the Greek island of Lemnos, to assess its benefits in contemporary medicine.

The clay may have been the precursor to the modern medicinal pill as early as the 1st millennium BCE, according to research by scientists from the University of Glasgow, the University of Strathclyde and the Technical University of Crete.

The Lemnian clay samples date from the 16th to the 18th centuries

ELIZABETH MCMEEKIN

Lemnian earth has been used for more than 2,500 years as a remedy for protecting against ingested or injected poisons and, during the post-medieval period, even against the plague. Historically, it was moulded into small pellets, stamped with a seal and consumed with liquids such as wine.

The research, published in the journal Plos One, suggests that the therapeutic properties of LE were likely to be due to a deliberate combination of specific clays and fungi. The study proposes that such combinations may produce compounds beneficial to gut bacteria, potentially aiding in maintaining a balanced gut microbiome, which is crucial for overall health.

“Regarding the LE, the precise recipe for its preparation remains, and is likely to remain, unclear, and further, it may have been modified over time. Investigating LE, and what has been known about it, has served as a springboard to investigate the modulation of the microbiome in a targeted fashion,” the paper says.

“Our data provide a potential mechanism by which fungus and clay co-cultures may be a valuable tool for manipulating the microbiota to prevent the progression of inflammatory diseases, and perhaps also limit intestinal infections: it therefore suggests avenues for the further development of ancient LE’s potential in a 21st-century context.”

Dr Effie Photos-Jones, an archaeological scientist from the University of Glasgow and the lead investigator of the project, said: “Our study began many years ago on the island of Lemnos in the northern Aegean, Greece. By examining historical LE samples [from the 16th-18th centuries] from Basel University’s Museum of Pharmacy we found that these samples contained specific types of fungi which were not present in the natural Lemnos clay.

“This led us to wonder if they were part of the original recipe. Ancient texts mention a ‘blessing’ ritual involving wheat and barley, suggesting that these grains — often infected during storage with certain fungi — might have been intentionally added. Speculating on this led, to our knowledge, to the first ever attempt to establish the presence and nature of microorganisms (bacteria, fungi) within ancient mineral therapeutics (DNA sequencing), following an approach developed by Dr Charles Knapp at Strathclyde University.”

After analysing historical LE samples from Basel University, the team cultivated their own fungus and clays (one a smectite-rich clay, and another using a kaolinite-rich clay) in a controlled environment to create bioactive compounds.

Simon Milling, professor of immunology at the University of Glasgow, added: “Our reconfigured 21st-century Lemnian earth shows that this ancient remedy has the potential to support good gut health for people living today.”

The researchers’ tests revealed that the combination of smectite clay and fungus showed broad antibacterial properties and uniquely positive effects on the gut microbiome.

Professor Danae Venieri from the Technical University of Crete said: “The results were very interesting. Testing against common pathogens showed that the combination of smectite clay and fungus had considerably better antibacterial activity compared to other clays and the control.”

Professor George E Christidis, also from the Technical University of Crete, said: “Clays which include iron and titanium compounds have been known to interact with micro-organisms (bacteria) but the role the clay minerals themselves play, which are the main constituents of clays, has not been previously considered important.”

Having healthy, diverse bacteria in the gut, also known as our microbiome, has been linked to many health benefits, including improving immune function and lowering the risk of heart disease.

Dr Umer Zeeshan Ijaz of the University of Glasgow’s James Watt School of Engineering added: “We are gaining increasing insight and confidence into how composition and function of the gut microbiome can be altered to improve health, leading to healthcare innovations and therapy development and allowing for disease management.”