Geology Talk

Smectite clay – a dog’s best friend!

About 10 years ago I wrote a column for Quarry (April 2008) called “Food for Thought”. The theme of the article was about geophagia – the consumption of soil – which is a common behaviour of many birds and animals.

The article mentioned that researchers studying wild chimpanzees noticed some of the animals suffering from severe diarrhoea were eating soils rich in clays that bind the toxins. My column this month is an expansion of that topic, which describes how the clay helps cure diarrhoea.

Unfortunately, this column is based on personal experience. Our dog Keiki (pronounced “Kay Kee”) suffered through severe diarrhoea brought on by a serious case of pancreatitis. That is a disease in which the pancreas becomes inflamed and releases digestive enzymes that are activated before they enter into the small intestine. Those enzymes caused Keiki to vomit, and have diarrhoea, and most critically, they attacked her pancreas.

{{quote-A:R-W:300-Q:"The top and bottom of each layer of smectite has a negative ionic charge."}}One of the medications that our vet gave Keiki was bio-sponge – one capsule twice a day. It turns out that bio-sponge is not some complex laboratory-created drug but is a naturally occurring clay called smectite.

There are many applications for smectite including iron foundry, oil well drilling, de-colourising oils, wine clarification, iron ore and feed pelletising, cat litter, oil and grease absorbents, and a carrier for insecticides, to mention just a few.

So how can a tiny amount of clay used primarily in industrial applications help cure an ailing puppy? I am not a vet, but I learned that the bacteria, bacterial toxins, viruses, and many decay products associated with pancreatitis or diarrhoea are adsorbed by the smectite, thus preventing them from being fixed to the membrane receptors on the cells of the intestines.

The secret lies in the properties of smectite. It is made up of many layers. Each individual layer consists of three even thinner layers that are attached to one another at the atomic level. Picture, for example, a piece of plywood made up of three thin plies of wood glued together. The top and bottom ply are the same, and the middle is different. Then picture a stack of many layers of plywood. That is what smectite looks like.

To put things into perspective, the smectite layers are very thin – about two nanometres thick, including the interlayer between two adjacent “pieces of plywood”. For comparison, a human hair is about 100 nanometres in diameter.

{{image2-a:r-w:300}}Now imagine peeling apart all those layers of smectite and laying them on the tabletop. They would cover a huge surface area. If you had a cubic centimetre of smectite and pulled apart all the layers they would cover about 50m2 (500,000cm2). Whew!

The top and bottom of each layer of smectite has a negative ionic charge. The nasty bacteria and so forth associated with pancreatitis and diarrhoea have a positive charge. Because negative charges attract positive charges, the surfaces of the negatively charged smectite layers adsorb the toxic substances by hydrogen bonding – sort of like sandwiching the bad molecules between the layers of the stack of plywood.

The smectite is capable of expanding as the toxins are absorbed between the clay layers creating lots of room to capture the nasty things that were making Keiki ill.

There are a few other ways that smectite helped cure what was ailing Keiki. Thankfully the skill of our vet, the smectite and the other meds did their job.

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