Ginko Biloba Leaves(AUSTIN, Texas, April 30, 2013) The New York Times (NYT) today ran an article [1] in its weekly “Science Times” section on the subject of the National Toxicology Program’s (NTP) recent toxicology report on a Chinese ginkgo (Ginkgo biloba) leaf extract. [2]

The NYT article was written by Roni Caryn Rabin, a freelance writer who frequently contributes to the Times. The article is under “The Consumer” header, and was titled, “New Doubts About Ginkgo Biloba.”

The initial four paragraphs of the article read as follows:

“Millions of Americans take ginkgo biloba supplements to boost memory and prevent dementia. Studies have never found any solid evidence that ginkgo does any such thing, but it did not seem to be doing much harm.“But last month, scientists released the first government toxicology study of ginkgo biloba, which found that the extract — one of the top-sellingherbal supplements in the country — caused cancer in lab animals, including an excessive number of liver and thyroid cancers, as well as nasal tumors.“The findings were somewhat surprising because ginkgo biloba has had a long and apparently benign history of human use. Although it has been associated with bleeding and cerebral hemorrhages in the elderly, there have generally been few reports of serious side effects.

“The results of the study do not confirm that ginkgo biloba is dangerous to humans, but it is disturbing that the laboratory animals all tended to suffer the same sorts of injuries, said Cynthia Rider of the

National Toxicology Program and the lead scientist of the ginkgo biloba study.”

Among several experts Ms. Rabin interviewed for this article was Mark Blumenthal, founder and executive director of the American Botanical Council (ABC), and Steven Dentali, PhD, chief science officer of the American Herbal Products Association (AHPA). Both organizations are named in the article as having “sharply criticized the study, saying that the ginkgo extract used had a different chemical composition than the extract typically sold in the United States.” Dr. Dentali was also quoted as having stated that, “This says nothing about toxicity in people, or what would be a safe dose in people. It’s just a crude tool toxicologists have to determine if something is harmful. If it hurts the animals, maybe it hurts people.”

On April 18, both ABC and AHPA issued statements referring to various limitations, concerns, and criticisms of the NTP report. [3,4] Both organizations had filed public comments in early 2012 with the NTP elaborating concerns in the draft NTP report that had been issued for public comment. (Access to the 2012 ABC and AHPA comments are provided.)

Of particular interest is the fact that even by the NTP’s own language in the report, the results of the report are not to be interpreted as being related to human health. According to the authors, “The actual determination of risk to humans from chemicals found to be carcinogenic in laboratory animals requires a wider analysis that extends beyond the purview of these studies.” [2]

ABC emphasized that the Shanghai Chinese ginkgo extract used in the two-year NTP study was not consistent with clinically tested ginkgo extracts or those standards for ginkgo extract that have been published in official compendial standards, such as national pharmacopeias. AHPA also noted that the Chinese extract was not consistent with those sold in the US market.

According to ABC’s Blumenthal, “Coverage of this subject in the New York Times will presumably result in more media outlets’ picking up this story and spreading to consumers and health professionals, creating what are probably unwarranted concerns about the long-term safety of appropriately manufactured ginkgo extracts.”

In addition, added Blumenthal, the Times’ statement that “Studies have never found any solid evidence that ginkgo [provides any benefit to ‘boost memory’ and ‘prevent dementia’]” is misleading. Blumenthal noted, as he had discussed with the reporter, that there is an impressive body of clinical evidence that the use of the leading German ginkgo extract does provide cognitive benefits to persons with mild dementia, among other noted benefits for patients with age-related cognitive impairment, including increases in quality of life.

John Shaw CEO of  The Natural Products Association (NPA),  the leading representative of the dietary supplement industry with more than 2,000 members, including suppliers and retailers of vitamins and other dietary supplements had this to say:

“On a daily basis, millions of consumers across the country turn to dietary supplements to improve their health and quality of life. Ginkgo biloba is one supplement that Americans have safely used for many years to support cognitive function. I’m disappointed that The New York Times chose to highlight a study that challenges the safety of ginkgo biloba.

NPA believes there are three major issues with the study from the National Toxicology Program. First, the study tested the effects of gingko biloba in animals, and these results cannot be directly translated to humans.

Second, the lab animals in this study were given quantities of ginkgo biloba that were much higher than humans would consume. The New York Times story even points this out, noting that “doses used in toxicology studies tend to be very high.” Mice received up to 2,000 milligrams per kilogram of body weight five times a week in this study; consumers take up to about 120 milligrams a day.

Finally, it has been found that the ginkgo extract used in the NTP study was not the same high-quality type that has been used in clinical trials establishing the benefits and safety of ginkgo biloba. NPA echoes the American Botanical Council stating “it is highly unfortunate that NTP chose to use this ginkgo extract as it means that the results of the NTP’s studies are not applicable to the standard-setting ginkgo extracts.”

The NTP study and the accompanying story from The New York Times should not deter consumers from taking ginkgo biloba. We encourage those interested in taking a new dietary supplement to consult their health care professional.

For more on the benefits of dietary supplements and other natural products, visit

Natural Products Association

The Natural Products Association (NPA), founded in 1936, is the largest and oldest nonprofit organization dedicated to the natural products industry. NPA represents over 2,000 members accounting for more than 10,000 locations of retailers, manufacturers, wholesalers and distributors of natural products, including foods, dietary supplements, and health/beauty aids. As the leading voice of the natural products industry, the NPA’s mission is to advocate for the rights of consumers to have access to products that will maintain and improve their health, and for the rights of retailers and suppliers to sell these products. Visit


1. Rabin RC. New doubts about ginkgo biloba. New York Times. April 29, 2013. Available at: Accessed April 30, 2013.

2. National Toxicology Program. NTP technical report on the toxicology and carcinogenesis studies of gingko biloba extract. Research Triangle Park, NC: National Toxicology Program. March 2013. Accessed April 30, 2013.

3. Many ginkgo extracts safe, says herbal science group [press release]. Austin, TX: American Botanical Council; April 18, 2013. Accessed April 30, 2013.

4. AHPA disputes the relevance of NTP report finding ginkgo causes cancer in mice [press release]. Silver Spring, MD: American Herbal Products Association; April 18, 2013. Accessed April 30, 2013.

5. Wang B-S, Wang H, Song Y-Y, et al. Effectiveness of standardized Ginkgo biloba extract on cognitive symptoms of dementia with a six-month treatment: a bivariate random effect meta-analysis. Pharmacopsychiatry. May 2010;43(3):86-91.