“Carefully conducted studies by the U.S. government found clear-cut evidence that aloe vera extracts caused intestinal cancers in male and female laboratory rats. For that reason, the nonprofit Center for Science in the Public Interest is giving aloe vera an "avoid" rating in its Chemical Cuisine guide to food additives. Taken orally, aloe vera can cause cramps and diarrhea,” CSPI wrote.
Decolorized vs. nondecolorized
The International Aloe Science Council (IASC) responded by saying that products made to IASC standards, using ‘decolorized’ aloe are safe. Only those products that are nondecolorized, containing high levels of aloins, a family of known digestive irritants, are cause for concern.
"The powerful laxative effect from ingesting unpurified aloe vera products would make it obvious if that's what people were consuming," said IASC executive director Devon Powell. "Decolorized (or purified) whole leaf aloe vera juice is devoid of the toxic chemicals that have caused so much concern, yet CSPI seems willing to make uninformed and sensational comments that will only serve to confuse and frighten consumers despite the facts."
The International Agency for Research on Cancer (IARC) recently published aloe vera carcinogenicity information and determined that unpurified whole leaf aloe vera juice is possibly carcinogenic to humans due to its aloin content. The IARC report also noted that purification by decolorization removes the toxic latex constituents of concern.
CSPI’s recommendation appears to be based on a study conducted in 2012 that was criticized by IASC for not making clear what form of aloe is commonly offered in the marketplace.
Aloe juice in its base, “nondecolorized” form, contains a number of compounds such as latex anthrones and anthraquinones—together known as aloins—that are known to be intestinal irritants. The IASC specifies that materials in the marketplace intended for consumption as opposed to topical use should be very low in these compounds, which are removed in the decolorizing process.
The study, by researchers from the National Center for Toxicological Research at the Food and Drug Administration indicated that "Aloe vera whole-leaf extract" is an intestinal irritant in rats and mice and a carcinogen of the large intestine in rats.
Stephen Dentali, PhD, who was then the science adviser of IASC, wrote a letter to the editor of Toxicological Sciences, where the study appeared. "At issue for IASC is that the article "omits a vital test-material qualifier from the title and throughout the article," Dentali wrote. "The research was conducted on nondecolorized aloe vera whole leaf extract, and inclusion of the term nondecolorized in the description of the tested plant material is essential to ensure that it is accurately identified. ... Failure to disclose this important distinction in the identity of the tested ingredient is simply inaccurate and grossly misleading.
"Our concern is that while it may be technically correct to leave out 'non-decolorized' from the title of the research article, it's liable to mislead consumers without it," Dentali wrote.
The IASC created and manages a third-party certification program that ensures the content and purity of aloe vera products. Products in the program are analytically tested for aloin content to ensure compliance with a maximum limit of 10 parts per million. Consumers can look for the IASC seal to purchase IASC certified products.
Speaking on the IASC's third-party certification program for aloe vera products, Mr. Powell said, "The vast majority of certified aloevera products contain less than 1 ppm aloin. The IASC does not certify unpurified aloe vera products and discourages their use. Although unpurified products are not as widely available we encourage customer awareness and avoidance of them,” Powell said.