Aluminium silicate (Kaolin)

Kaolin, formally known as aluminium silicate, is a naturally occurring white clay mineral composed primarily of kaolinite. In food applications it functions as an anti-caking agent in powdered products and as a surface treatment on some fresh fruits, preventing moisture uptake and maintaining free-flow during storage and distribution. It has a long history of use in ceramics, paper, and cosmetics, and its food-grade form is held to stricter purity standards.

JECFA reviewed kaolin as a food additive in 2006 and issued a "not allocated" ADI, indicating that the available toxicological data were insufficient to establish a numerical daily intake value. This outcome reflects a precautionary approach to aluminosilicate compounds in general, driven by concerns about total dietary aluminium intake rather than specific evidence of harm from kaolin at typical food use levels. Aluminium in kaolin is present as a structural mineral component and is less bioavailable than ionic aluminium, but regulatory agencies remain cautious about cumulative aluminium exposure.

Kaolin is approved in the EU as E559 for use in certain food categories at defined maximum levels. Some regulatory bodies classify it as a processing aid in specific applications, which can affect whether it appears on product labels. The EFSA has highlighted total dietary aluminium — from additives, natural food content, and packaging migration combined — as an area warranting ongoing consumer monitoring. Healthy adults efficiently excrete aluminium through the kidneys, but vulnerable groups including young children, pregnant women, and individuals with renal impairment may have reduced clearance capacity. Consumers who prefer to limit aluminium-containing additives can check labels for E559 alongside related codes E554–E556.