On June 3, the Center for Science in the Public Interest (CSPI) sent a letter to the US Food and Drug Administration (FDA) and issued a press release both “urging the FDA to take actions to protect consumers from” Ginkgo biloba leaf extracts, which, CSPI purported “[cause] cancer in animals and presumably in people.”

These developments come after the publication of a March 2013 National Toxicology Program (NTP) report linking the two-year force-feeding of an atypical Ginkgo biloba extract (GBE) to certain cancers in laboratory mice and rats. One month after the report, CSPI downgraded the herb’s Chemical Cuisine safety rating to “avoid” from its previous rating of “safe.”

CSPI asked the FDA to give companies a “reasonable time” to recall from the marketplace any Ginkgo biloba-containing products, such as dietary supplements, after which point the group suggested FDA should seize any products remaining on the shelves.

Despite CSPI’s sense of urgency on this issue, the American Botanical Council (ABC) has made clear in a recent member advisory, news release, and an article in the May issue of HerbalEGram that animal toxicology studies have questionable relevance to humans. As the NTP report notes in the foreword, “Extrapolation of these results to other species, including characterization of hazards and risks to humans, requires analyses beyond the intent of these reports.” [Emphasis added]

ABC has identified three main areas of concern, including, but not limited to the following:

(1) the application of toxicology and carcinogenicity studies in rodent models has questionable and debated relevance to actual human use;

(2) the extract used in the studies does not appear to conform to the GBEs listed in internationally recognized pharmacopoeias or other compendia; and

(3) such GBEs have been the subject of numerous preclinical studies and dozens of human clinical trials and have a reasonably long history of safe use and known benefits.

These points were first mentioned in ABC comments filed with the FDA in early 2012, when a draft version of the report was open to public comment.

Although CSPI has begun to make its case to the FDA, the final decision rests with the Administration. As reported in an article from The New York Daily News, FDA Spokesperson Tamara N. Ward hinted that more evidence might be needed for the Agency to take any drastic action.

“While FDA is concerned about the findings of the studies, and will consider the implications it may have for the safety of dietary supplements containing gingko biloba [sic], it is not scientifically valid to conclude with certainty that dietary supplement products containing gingko biloba are unsafe based solely on data from the new NTP study,” Ward was quoted as saying in the Daily News article. [Emphasis added] “In the study, rats and mice were fed amounts of gingko biloba extracts (by body weight) that may be considerably greater from those which a consumer would normally ingest from a dietary supplement product containing gingko biloba. In addition, there may be differences in the extract used in these studies in contrast to what is available on the market for gingko biloba dietary supplements.”