Geophagy is (or was) common, from the equator to northern Europe. Although pica comes in many forms, most examples of geophagy ("earth eating") involve consumption of clay soils. This article suggests an adaptive explanation:
The gist is that clay stops the absorption of antinuntrients. In times of scarcity the behavior permits the eating of otherwise unpalatable foods. Could a clay supplement "shore up" a damaged gut in much the same way?
there is lavos heilerde sold in germany for such issues. ultrafine, ultrafine its for binding cholesterol, and then there is fine and normal. one for the skin and the other one for digestive problems, flushy pooh and gasses and also digestion problems. there is also green clay in german health food store. there is another clay supplement sold in usa. i remeber its this superchargend vegan supplement from this rawvegan bodybuilder.