Home
[an error occurred while processing this directive]
Quality survey Health benefits Safety Reading labels Ask the supplier Standards & regulations



Editorials





Testing news
Search
Links
Glossary
Glossary
Ask the expert
Bookstore
Sponsorship
Contact us
Disclaimer
Privacy policy
Sponsorship
 

Research news

Leading Herbal Experts Urge Perspective on Ginkgo
Washington DC, 20 August 2002

Concerned that reports about an article examining the use of ginkgo in healthy subjects will cause consumers to avoid or abandon the use of this beneficial herb, two of the natural products industry's leading trade groups, the American Herbal Products Association (AHPA) and the National Nutritional Foods Association (NNFA) urge reporters and consumers to put this new study in context with the total body of positive research on this therapeutic botanical. The study, which was published in the recent edition of the Journal of the American Medical Association, was conducted by researchers at Williams College from 1996-1998.*

"While this study shows that ginkgo did not have an effect on elderly adults with unimpaired mental function, there are more current well-designed studies** that have also analyzed people with normal mental function that arrive at directly contradictory conclusions," said Phil Harvey, PhD, NNFA's director of science and quality assurance. "These more current studies report significant improvement in the study subjects' memory, attention and cognitive clarity due to the use of ginkgo."

The authors of the new study acknowledge that their "study has limitations" and that higher doses of ginkgo over a longer period of time may yield different results.

"What's important to remember is that it's difficult to increase cognitive ability in healthy adults to a significant or even measurable degree. To do so would likely require a longer trial, with doses of ginkgo titrated to a higher level over time," reiterated Harvey.

"Let's not forget that over a half a century of controlled trials on ginkgo have clearly demonstrated that those with even mild to moderate memory problems and poor concentration -- symptoms often associated with the onset of Alzheimer's and other dementias -- are helped by taking ginkgo," said Steven Dentali, PhD, AHPA's vice president for scientific and technical affairs. "This study should not be the last word on ginkgo's effectiveness. Previous well-designed and executed studies have indicated ginkgo's significant benefits in improving circulation and mental function and should be taken seriously as a totality of scientific evidence about ginkgo."

One of the most clinically studied botanicals, ginkgo has been examined mainly for its potential to increase circulation to the extremities as well as the brain, especially in the elderly. It has also been studied for the treatment of ringing in the ears (tinnitus), male impotence, degenerative nerve conditions such as multiple sclerosis, and other conditions.

The first large-scale American clinical study on ginkgo was published in 1997, also in JAMA,*** focusing on ginkgo's effect on improving the short-term memory of early diagnosed Alzheimer's disease. The researchers concluded that the herb is safe and stabilizing, and that, in a significant number of patients, it improves cognitive performance and social functioning.

Founded in 1983, the American Herbal Products Association (AHPA) represents the finest manufacturers, growers, suppliers and retailers of herbal supplement products. AHPA serves its members by promoting the responsible manufacture and sale of products that contain herbs.

The National Nutritional Foods Association (NNFA) is the nation's largest and oldest non-profit organization dedicated to the natural products industry. NNFA represents more than 4,000 retailers, manufacturers, wholesalers and distributors of natural products, including foods, dietary supplements, and health and beauty aids.

* Solomon PR, Adams F, Silver A, Zimmer J, Deveaux R. "Ginkgo for Memory Enhancement: A randomized controlled trial." Journal of the American Medical Association, 2002;288(7):835-40.

** Mix, JA., Crew WD. "A double-blind, placebo controlled randomized trial of Ginkgo Biloba extract EGb761 in a sample of cognitively intact older adults: neuropsycological findings." Human Psycophamracology Clin Exp 2002; 17:267-77.

*** Lebars PL, et. al. "Ginkgo Biloba for dementia." Journal of the American Medical Association, 1997;278:1327-1332.

Source

American Herbal Products Association & National Nutritional Foods.end-of-story


Herb Science Group Clarifies Clinically-Documented Benefits of Ginkgo Extract
Austin TX, 20 August 2002

Impressive evidence in the scientific and clinical literature supports the benefits and safety of the popular herb ginkgo, according to the nonprofit American Botanical Council (ABC). The information from ABC comes at the same time as a new study published in the Journal of the American Medical Association (JAMA) in which ginkgo extract did not increase mental function in normal, healthy older patients.* The six-week randomized study tested healthy adults for learning, memory, attention, concentration, and verbal fluency using the standard dose of 120 mg ginkgo extract per day. The study was conducted by researchers at Williams College in Williamstown, Massachusetts.

"The value of ginkgo or any dietary supplement cannot be determined on the basis of one study alone," said Mark Blumenthal, founder and executive director of ABC. "There are more than 125 clinical trials published on ginkgo extract over the past two decades, with most of them supporting numerous important benefits related to improved circulation and mental function."

Blumenthal added that several recent articles reviewing the medical literature have supported the cognitive (mental) benefits of ginkgo in patients with early stages of dementia, and a one-year study published in JAMA in 1997 supported the benefits of using ginkgo to retard the progression of symptoms in early stages of Alzheimer's disease. Several recent studies have also shown cognitive benefits of ginkgo in healthy older adults, he added. In one study recently published in Human Psychopharmacology using a similar design with a higher dosage (180 mg per day), researchers observed clinically significant cognitive benefits in healthy individuals.**

There are dozens of positive clinical studies for ginkgo for cognitive disorders published in the scientific literature. Thirty-four clinical trials on ginkgo are summarized in an extensive monograph (technical paper) for healthcare practitioners in ABC's forthcoming new book, The ABC Clinical Guide to Herbs. All but two show positive benefits for memory and other mental functions, and for peripheral arterial occlusive disease, a condition characterized by pain in leg muscles during walking affecting many older adults. Other potential benefits suggested by several clinical studies include improved performance of hikers susceptible to lack of oxygen in high altitudes (mountain sickness), and male and female sexual dysfunction.

In 1994 the respected Commission E, the agency that approves the safety and efficacy of herbal medicines in Germany, considered the scientific and clinical information on ginkgo to be strong enough to approve ginkgo extract as safe and beneficial in treating certain cognitive and circulatory disorders, according to Blumenthal, who is also the senior editor of an English translation of the Commission E's monographs.

One potential question about the new study is the important research protocol of "blinding" the samples, so that neither the patients nor the researchers are able to distinguish test substances from placebos. The paper in JAMA noted that the placebo or dummy pills were made of gelatin capsules, while the actual ginkgo product is a small, coated tablet. Whether this made any significant difference in maintaining the blinding necessary to be classed a "double-blind" trial is not yet determinable, said Blumenthal.

A rational perspective on the significance of the new study is provided by psychopharmacologist Jerry Cott, PhD, an expert on dietary supplements and drugs that affect the mind and nervous systems: "It is very difficult to improve cognition in a normal person; it's much easier to improve in an impaired person. That is, normal functioning in a healthy person is like an upper limit; a person is already doing as well as can be expected. It is therefore very difficult to measure improved mental performance without a precise objective measurement scale."

Hyla Cass, MD, a psychiatrist and author in Los Angeles who successfully uses ginkgo in her clinical practice, expressed concern about the impact of the publicity that may be generated on the new clinical trial. "Heavy promotion of the outcomes of this study may result in a disservice to the public. It can turn people away from a safe, well-researched product that previous research has proven can improve their quality of life," she explained. Dr. Cass has also found ginkgo to be helpful in treating male sexual dysfunction that has declined with age (often due to impaired circulation), a well as sexual problems associated with the use of certain types of antidepressant drugs.

Ginkgo preparations are made from the leaf of the ginkgo tree (Latin name Ginkgo biloba), the world's oldest living tree, dating back 250 million years. Ginkgo trees were found living in China and northern Japan, and are now grown for commercial cultivation in the US and other countries. Extracts from ginkgo leaves are pharmaceutically concentrated and standardized to some of ginkgo's unique biologically active chemical compounds. The leading most well-researched ginkgo extract from Germany is licensed as a medicine in many countries worldwide. Ginkgo is also the top-selling herbal dietary supplement in the US for the past five years, according to information in ABC's peer-reviewed journal, HerbalGram.

The American Botanical Council (ABC) is the nation's leading nonprofit organization addressing research and educational issues regarding herbs and medicinal plants. The 13-year-old organization occupies a 2.5 acre site in Austin, Texas where it publishes HerbalGram, a peer-reviewed journal on herbal medicine, and will publish a forthcoming book and continuing education course for healthcare professionals, The ABC Clinical Guide to Herbs, containing an extensive science-based monograph on the safety and efficacy of ginkgo.

*Solomon PR, Adams F, Silver A, Zimmer J, DeVeaux R. "Ginkgo for memory enhancement: A randomized controlled trial." Journal of the American Medical Association, 2002;288(7):835-40.

** Mix JA, Crews WD. "A double-blind, placebo-controlled, randomized trial of Ginkgo biloba extract EGb 761 in a sample of cognitively intact older adults: neuropsychological findings." Human Psychopharmacol Clin Exp 2002;17:267-77.

Source

American Botanical Council.end-of-story

 

 

   
[an error occurred while processing this directive]
Health benefits Safety Reading labels Ask the supplier Standards & regulations Contact us

(c) Copyright 1999-2003 Dietary Supplement Quality Initiative. For permission to reprint, please contact our editor.