Aloe vera has become a popular ingredient in various health and cosmetic products. As its use has grown, so too have questions regarding its safety, particularly concerning a potential link to cancer.
Clarifying the Link: Aloe Vera and Cancer Risk
Concerns about aloe vera and cancer stem from animal studies by the National Toxicology Program (NTP). These studies linked orally administered non-decolorized whole leaf aloe vera extract to increased intestinal tumors in rats and mice. The responsible compound is aloin, a yellowish-brown substance found in the latex, the bitter sap located just beneath the outer skin of the aloe leaf. Aloin is a type of anthraquinone, known for its laxative effects.
The International Agency for Research on Cancer (IARC) classifies the whole leaf extract of aloe vera, specifically the non-decolorized form, as a possible carcinogen to humans (Group 2B). However, commercial aloe vera products are typically processed to remove aloin and are considered safe. The concentrations of aloin used in the animal studies were significantly higher than those present in properly processed aloe vera products available to consumers.
Distinguishing Aloe Vera Forms
The processing of aloe vera components fundamentally impacts their safety. The whole leaf includes the outer rind, the inner clear gel, and the yellow latex layer situated between them. This latex layer is where aloin is concentrated, with natural levels potentially reaching 10,000 parts per million (ppm). Unprocessed, non-decolorized whole leaf extract, retaining high levels of aloin, was the subject of the cancer concerns.
To mitigate the risks associated with aloin, commercial manufacturers employ a purification process known as decolorization. This process removes the aloin and other anthraquinones from the whole leaf extract. The resulting decolorized whole leaf extract is considered safe for consumption, with aloin content typically reduced to below 10 ppm for oral products, a level deemed safe by industry standards. Alternatively, aloe vera gel, also known as inner leaf fillet, is extracted solely from the clear, mucilaginous substance inside the leaf, deliberately excluding the outer leaf and the aloin-rich latex. This inner gel is naturally very low in aloin, making it suitable for topical and internal uses.
Guidelines for Safe Aloe Vera Use
For internal consumption, select aloe vera products labeled “decolorized,” “purified,” or “aloin-free.” These products are processed to reduce the aloin content to safe levels, typically under 10 ppm for drinkable products. Consumers should avoid consuming raw, unprocessed whole leaf aloe vera or homemade preparations that do not guarantee the removal of the aloin-containing latex. Ingesting products with high aloin content can lead to gastrointestinal discomfort, including cramps and diarrhea.
For topical use, such as for skin soothing, aloe vera gel is generally safe for most individuals. It is advisable to perform a patch test on a small area of skin first to check for any sensitivities or allergic reactions, although these are uncommon. Individuals who are pregnant, breastfeeding, or taking any medications should consult a healthcare professional before using oral aloe vera products, as potential interactions with certain drugs or health conditions have been noted.