California puts aloe vera extract and goldenseal on list of known carcinogens

California puts aloe vera extract and goldenseal on list of known carcinogens

California recently added aloe vera ("non-decolorized whole leaf extract") and goldenseal root powder to the list of "chemicals known to the State of California to cause cancer." Under California law, businesses have 12 months to either reformulate their products or provide a "clear and reasonable" warning before knowingly and intentionally exposing anyone to these substances." "Countless" dietary supplements and cosmetic products containing aloe vera and goldenseal will be affected.

The addition was brought about by the International Agency for Research on Cancer (IARC) listing these substances as "possibly carcinogenic to humans."  That determination is based on what the IARC deems sufficient evidence of carcinogenicity in experimental animals. The listing applies to all routes of exposure, such as oral ingestion and topical application.

According to the California Office of Environmental Health Hazard Assessment (OEHHA), once the IARC identifies a substance as carcinogenic, it must be added to state's list (known as the Proposition 65, or "Prop 65" list) under California law.Thus, while some public comments to OEHHA's action tried to argue with the scientific basis for the listing, OEHHA said its action was "ministerial" and not open to discussion.

Commenters included industry trade groups like the American Herbal Products Association and the euphemistically-named Council for Responsible Nutrition.  Other commenters were individuals associated with sellers of dietary supplements and "natural" cosmetics. Among their comments were the argument from antiquity ("used for thousands of years") and a sort of post hoc ergo propter hoc reasoning ("never heard of anybody getting cancer").

It is always interesting to see how quickly those who regularly sell products with health claims supported by flimsy evidence convert to aficionados of the scientific method when they feel it's in their best interest.  Commenters pointed out that the decision was based on rat, not human, studies, and that "the poison is in the dose."

This is not aloe's first run-in with the authorities. In 2002, the FDA required laxative manufacturers to remove aloe from its products because safety had not been adequately demonstrated. It is widely touted for its supposedly beneficial effects on digestive problems, such as constipation.

Ironically, one study found that, in the words of the journal article title: "Aloe vera non-decolorized whole leaf extract-induced large intestinal tumors in F344 rats share similar molecular pathways with human sporadic colorectal tumors." Apparently, its supposedly beneficial effects on the intestine might not be so beneficial after all.

Equally ironic is the fact that goldenseal is touted as effective against cancer, an unproven claim. For example, one "integrative oncology" website carries this tempting, but misleading, headline: "Get Metformin-like Anti-Cancer Activity without a Prescription (Berberine)." (Berberine is the active ingredient in goldenseal root.)

Listing two popular "natural" remedies as possibly carcinogenic is just the latest in a long list of nasty surprises precipitated by the laissez faire regulatory atmosphere enjoyed by the dietary supplement industry. Here, once again, a government agency is playing catch up in trying to curb the harm, both potential and real, brought about by the extremely lucrative trade in "natural" products. 

Points of Interest 12/13/15
Points of Interest 12/10/2015

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