Geophagia



The ancient practice known as geophagia or geophagy (the practice of eating dirt or clay) has popped up numerous times in history and has of course been incorporated into diet woo.

Sketchy "health" stores tend to sell jars of clay, and the cable channel "Animal Planet" was happy to advertise for them when their oddity show was talking about macaws. Macaws, unlike humans, actually have a digestive system designed for eating clay.

One of the more recent incarnations of geophagia, the Clay Cleanse Diet (CCD) is an alternative medicine fad diet that claims that ingesting clay can reduce weight and remove toxins and surfaced around 2014 as a potential weight loss method.

All of this is a terrible idea and you shouldn't do it.

That being said, there is a nugget of truth in geophagia as a detoxification method. It has been demonstrated that geophagia in association with potato eating, particularly the more toxic wild potatoes in times of famine, has a detoxification effect. Detoxification has also been suggested as an adaptive function in non-human primates but as not been shown experimentally. Geophagia is further linked to to plant domestication, at least in the case of potatoes.

Weight loss
CCD itself is probably effective at weight loss. The clay does expand in the stomach, and will make people feel significantly more constipated less hungry. Users of the diet claim to have lost 10 pounds over 10 days. If you wish to lose weight with a quick time scale but comparable health risks, you might consider removing unnecessary limbs or deliberately losing blood.

Cleansing
As a cleanser clay removes absolutely nothing "toxins" from the body by doing stuff. The users of this diet fail to present any scientific evidence that it removes "toxins" from the body, or what those toxins are, as is typical for "cleansing" claims. Kaolinite and montmorillonite clays have been shown to adsorb heavy metals in vitro, not in humans specifically.

Safety
CCD itself is not safe and should be avoided. It can potentially contain high levels of heavy metals, soil-based pathogens (nematodes and microbes), can block your colon, and can damage your stomach and intestines. Geophagia has been associated with hyperkalemia (excessive potassium in the blood), resulting in cardiac arrest and paralysis in five patients with chronic renal failure.

Other Geophagia
Sandersville, Georgia is the "Kaolin Capital of the World", and likely also the epicenter of geophagia in the United States.

Pica
is a condition characterized by an urge to eat soil (among other non-nutritive things, such as sand and utensils) due to chemical imbalance, neurological response to iron deficiency, etc. It is particularly common among small children, pregnant women, and those with developmental disabilities.

Basic sustenance in poverty
Poor (dirt-poor?) Haitians sometimes eat a yellow dirt with added salt and vegetable shortening because they cannot afford rice. This way starving to death is less of a painful experience, and takes a long enough time that someone might notice their plight.

Other animals
Many animals eat dirt, primarily to get missing nutrients (especially salt). Confined farm animals are especially prone to geophagia, and goats are reported to suffer from gastro-intestinal lesions from geophagia.