The Aloe genus comprises approximately 250 species of succulent dry climate plants (xerophytes). The best known species is Aloe barbadensis (syn. Aloe vera), the inner leaf pulp of which has many uses in the food and cosmetics sector as Aloe vera gel. 

In addition to Aloe barbadensis, however, other Aloe species are used for many different purposes. Inter alia, the sap of the pressed, whole, unpeeled leaves of Aloe arborescens (krantz aloe, candelabra aloe) is marketed in the form of food supplements. The German Federal Institute for Risk Assessment (BfR) has assessed the possible health risks of such food supplements. The outer layers of the leaves of Aloe arborescens are of toxicological relevance. As with all Aloe species, these layers contain plant-based anthranoids which have long been suspected of having a genotoxic and carcinogenic effect. In addition to data on the pure substances, tests have also been conducted in the meantime on anthranoid-containing preparations made from Aloe leaves. The results of these long-term studies also confirm the suspicion of carcinogenicity, but there are data gaps which should be closed with regard to the details and mechanisms of cancer development.