On Thursday, The Center for Science in the Public Interest (CSPI) advised consumers to avoid Ginkgo biloba, based on a new government study that showed evidence of the extract causing liver cancer in mice and thyroid cancer in rats. On its Chemical Cuisine guide to food additives, CSPI downgraded ginkgo from “safe” to “avoid.”

While extracts from the leaves of the Ginkgo biloba tree are legally used as an herbal remedy to improve memory and brain function, the Food and Drug Administration has sent warning labels to companies using Gingko in energy drinks, such as Rockstar, stating that the extract is not generally recognized as safe as a food product.

“Ginkgo has been used in recent years to let companies pretend that supplements or energy drinks or supplements with it confer some sort of benefit for memory or concentration,” said CSPI executive director Michael F. Jacobson.  “The evidence for those claims has been dubious, at best.  The pretend benefits are now outweighed by the real risk of harm.”

“I always prescribe Chinese herbs exclusively in the manner in which they have been used safely and traditionally for over 3,000 years,” Lisl Meredith Huebner, Dipl.CH, RH, a nationally board certified Chinese Herbalist and Registered Clinical Herbalist in the Greater Hartford area, said in an interview on Thursday. “I wish that the Western mind would take heed of the tried and true methodology.”

The government’s National Toxicology Program (NTP) used a special formulation of a Chinese Ginkgo extract given to certain strains of rats and mice five times a week for two years in a series of animal toxicology studies.

The NTP researchers stated, “We conclude that Ginkgo biloba extract caused cancers of the thyroid gland in male and female rats and male mice and cancers of the liver in male and female mice.”

According to the nonprofit American Botanical Council (ABC), clinically tested Ginkgo extracts sold as dietary supplements in the United States are safe for most consumers.

“The ginkgo extract used in this study is different from the high-quality ginkgo extracts used in published clinical trials showing safety and various beneficial activities of ginkgo,” said Mark Blumenthal, founder and executive director of ABC, in a statement released on Thursday. “That is, the Shanghai ginkgo extract used by NTP does not represent the quality of German ginkgo extract that is the world standard for ginkgo. 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.”

Additionally, the NTP studies contain dosage levels equivalent to 50 to 100 times higher than what would normally be ingested by consumers, ABC’s consulting toxicologist calculated.

“Almost anything will create cancer in rats and mice when it’s fed to them at high doses for two years,” said Bill J. Gurley, PhD, professor of pharmaceutical sciences in the College of Pharmacy at the University of Arkansas School for Medical Sciences, Little Rock.

“Even the reviewers voiced adamant proclamations that the results in this animal research were not intended for direct extrapolation to humans,” said Rick Kingston, PharmD, president of regulatory and scientific affairs at SafetyCall International in Minneapolis, MN, and professor of pharmacy at the University of Minnesota College of Pharmacy.

While Ginkgo has gained recent popularity as a treatment for dementia and Alzheimer’s, China (and later Japan and Korea) has long recognized the more extensive medicinal benefits of Gingko. According to Huebner, its leaves of contain a unique, allergy-controlling compound, a Platelet Activating Factor, which inhibits blood cells from sticking to each other, improving circulation. Improved micro-circulation and circulation to the head not only increases cognition, memory, senility and focus; it also affects hearing, mood and eye disease.

Huebner writes that various studies have shown that the increased blood flow effect of Gingko leaves improve the conditions of peripheral blood circulation, varicose veins, arthritis and rheumatism, as well as disperse clots and increase coronary and capillary circulation. It helps lower cholesterol, treat arteriosclerosis (hardening of the arteries) and relieve chest pressure and pain. Gingko is also a powerful antioxidant.

“The ginkgo nut has been used medicinally in China for thousands of years for the treatment of lung disorders and “Damp” conditions (as classified in Traditional Chinese Medicine),” wrote Huebner.  Used as an expectorant, Ginkgo can dilate the bronchia and blood vessels to treat coughs, asthma and wheezing. Damp conditions include urinary problems, such as incontinence.

Huebner wrote, “Ginkgo nuts are antifungal and antibacterial, considered to be somewhat astringent, slightly sedative and are a frequent addition to TCM formulas treating urinary and bronchial ailments as well as diseases of the reproductive organs.”