Ancient people knew that some kinds of clay have healing qualities. They rubbed clay on their skin to cover wounds. They also used the natural rock or soil material to treat stomach problems.

Now, American researchers have discovered how different clays work as medicine. They are researching the effectiveness of clays against antibiotic-resistant infections.

Blue and green clays are found in volcanic areas of the world. Around volcanoes, native peoples used the clays to improve their health. It seems they knew what they were doing.

Blue and green clay might be able to kill MRSA (Methicillin-resistant Staphylococcus aureus). MRSA is an antibiotic resistant bacteria, sometimes called a superbug. (REUTERS)

Lynda Williams is a clay and mineral scientist. She works at Arizona State University's School of Earth and Space Exploration in Tempe. She and her research team have been studying the Aboriginal people of Australia.

"There is evidence of Aboriginals using clays for treating wounds and they eat it. Many cultures eat clays to settle their stomach."

Williams and her team found the clay was effective against some pathogens. Pathogens are bacteria and viruses that cause disease. They examined bacteria that have developed resistance to other antibiotics.

In laboratory tests, they saw how a blue-colored clay is effective against the drug-resistant Staphylococcus aureus, known as MRSA. MRSA is a dangerous and sometimes deadly skin infection.

The clay was also effective in treating Buruli ulcer, a skin disease found in the Ivory Coast.

Here is how the blue clay works. Iron is one of the chemicals found in the clay. The bacteria need the iron to survive.

Some of these same clays also contain aluminum. The minerals work together. Lynda Williams says aluminum lets iron flood into harmful bacteria. The iron oxidizes and then kills the bacteria.

"In the end, what we found is that aluminum is attacking the proteins in the cell wall of the bacterium and allowing pores to open so that iron, reduced iron 2, goes into the interior of the bacterium, (and) has reactions with the protein inside. It becomes oxidized and it destroys the biomolecules inside the cell, killing the bacteria."Williams says she hopes the study will interest drug companies that want to explore the healing properties of blue and green clays.

The National Science Foundation provided financial support for the study. Williams and her colleagues reported their findings in the journal Nature Scientific Reports.

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Words in This Story

pathogen – n. something such as bacteria or a virus that causes disease

oxidize – v. to change (a compound) by increasing the proportion of the electronegative part or change (an element or ion) from a lower to a higher positive valence; remove one or more electrons from (an atom, ion, or molecule)

antibiotic – n. a drug that is used to kill harmful bacteria and to cure infections

pore – n. a small opening, especially in an animal or plant, on by which matter passes through a membrane