U.S. Food and Drug Administration. Kaolin was also used to treat cholera around the start of the 20th century. An early proponent was German physician Julius Stumpf. Heavy metal chelation It has been used as a scientifically unsupported chelation treatment for heart disease and autism. Aflatoxicosis Bentonite has the ability to reduce the adverse effects of aflatoxicosis. Side effects of ingestion Substances discontinued such as kaolin and attapulgite were formerly considered gastric demulcents and diarrhea medication, until official studies by the USFDA disproved these views. Clays are classified as excipients and their main side-effects are that of neutral excipients, which is to impair and slow down absorption of antibiotics, hormones and heart medication amongst others by coating the digestive tract and this slowed down absorption can lead to increased toxicity of some medication (e.g. citrate salts) which can become toxic if not metabolized quickly enough, which is one contraindication of attapulgite. Usual mild side-effects are nausea, slowed down absorption of nutrients from food (in excess dosage of medicinal clay) and constipation. It has been found that prolonged exposure to bentonite in humans can actually have harmful effects. Common medicinal clays Bentonite-type clay has been used to treat infections, indigestion, and other medical problems by both applying wet clay topically to the skin as a poultice, and by ingesting it. Bentonite has been prescribed as a bulk laxative, and it is also used as a base for many dermatologic formulas. Dermatologically, it is used as part of a treatment for pruritus. Bentonite itself is not classified as a carcinogen, but some bentonite may contain variable amounts of respirable crystalline silica, a human carcinogen. Montmorillonite is the main constituent of bentonite and Heilerde loess. A medical preparation is called diosmectite. Palygorskite or attapulgite is a very absorbent clay, somewhat similar to bentonite. When used in medicine, it physically binds to acids and toxic substances in the stomach and digestive tract. For this reason, it has been used in several anti-diarrheal medications, but studies of such have since been rejected by the U.S. Food and Drug Administration as insufficient. Kaolin is not as absorbent as most clays used medicinally (it has a low shrink-swell capacity). Also, it has a low cation exchange capacity. This clay is also known as 'white cosmetic clay'. Clay, in the form of kaolin, was a common ingredient in western medicines such as Kaopectate, Rolaids and Maalox, but is