Aloe vera, a succulent plant, has been widely recognized and utilized for centuries due to its perceived benefits in health and beauty applications. Despite its popularity, concerns have emerged regarding its safety, particularly a potential link to cancer. This article explores the scientific evidence on whether aloe vera is carcinogenic.
Understanding Aloe Vera Preparations
The term “aloe vera” does not refer to a single, uniform product; instead, it encompasses various preparations derived from different parts of the plant. Each form contains varying concentrations of compounds, which is important for understanding its safety profile. The outer green rind of the aloe leaf, along with the yellow latex layer just beneath it, contributes to what is known as whole leaf extract. This extract includes compounds called anthraquinones, such as aloin.
Aloe vera latex is the bitter, yellowish fluid that seeps from the plant when a leaf is cut. This latex is particularly rich in anthraquinones like aloin, known for their strong laxative effects. In contrast, aloe vera gel is the clear, mucilaginous substance found in the innermost part of the leaf, often referred to as the inner leaf fillet. This gel is typically processed to remove the aloin-containing latex, resulting in a product distinct from whole leaf extracts or latex. The presence and concentration of these compounds, especially aloin, differ significantly across these preparations, influencing their potential effects.
Scientific Research on Carcinogenicity
Scientific investigations have addressed the potential carcinogenicity of certain aloe vera preparations, with significant findings from animal studies. The National Toxicology Program (NTP) conducted a two-year study, published in 2013, which found clear evidence of carcinogenic activity in rats. This study involved oral administration of non-decolorized whole-leaf aloe vera extract in drinking water, identifying anthraquinone compounds, particularly aloin, as the substances of concern. The aloin content in the whole leaf extract used in this NTP study was notably high, ranging from 10,000 to 13,000 mg/L.
It is important to distinguish between the non-decolorized whole-leaf extract used in the NTP study and the decolorized or purified aloe vera gel commonly found in oral supplements and beverages. Purified aloe vera gel products are processed to remove aloin and other anthraquinones. While human studies on aloe vera and cancer are limited and often inconclusive, the mechanism of action observed in animal models, such as DNA damage, raises concerns. These animal findings do not always directly translate to humans, but they provide a basis for caution regarding specific types of aloe vera preparations.
Official Warnings and Safe Consumption
Regulatory bodies and scientific organizations have issued classifications and warnings regarding certain aloe vera preparations based on available research. The International Agency for Research on Cancer (IARC) classifies whole-leaf extract of Aloe vera as “possibly carcinogenic to humans” (Group 2B).
For safe consumption, it is advised to avoid oral products made from whole-leaf aloe vera extract or those containing aloe latex, due to their aloin content. Products labeled as “decolorized,” “purified,” or “aloin-free,” which typically refer to the inner leaf gel, are generally considered safer for oral consumption. This is because the potentially problematic compounds have been significantly reduced or removed. The International Aloe Science Council (IASC) recommends that oral aloe products contain less than 10 parts per million (ppm) of aloin.
Topical use of aloe vera gel, for instance, for skin irritation, is widely considered safe, as the problematic compounds are poorly absorbed through the skin. Consumers should carefully check product labels for “aloin-free” or “decolorized whole leaf” and consult a healthcare professional before internal use.