A flawed study published in the August 21, 2002 issue of JAMA claims that ginkgo doesn’t enhance memory or intelligence in healthy elderly adults. But don’t worry. We’ll show you where the researchers went wrong, and why you can still trust high-bilobolide, low ginkgolic acid ginkgo biloba supplements to:
- Boost brain power
- Protect cells from free radical damage Improve blood circulation
- Strengthen and protect your veins and arteries
- Increase your odds of living longer
The study: JAMA. 2002;288:835-840
Ginkgo for Memory Enhancement: A Randomized Controlled Trial
(Paul R. Solomon, PhD; Felicity Adams, BA; Amanda Silver, BA; Jill Zimmer, BA; Richard DeVeaux, PhD)
The objective:
To evaluate whether ginkgo, an over-the-counter agent marketed as enhancing memory, improves memory in elderly adults as measured by objective neuropsychological tests and subjective ratings.
Who participated?
230 participants (98 men and 132 women), between the ages of 60 and 82, who were in generally good health, had Mini-Mental State Examination scores greater than 26, and enrolled over a 26-month period from July 1996 to September 1998.
Comment:
These people replied to a newspaper ad asking for community members to participate in a study investigating a new drug for improving memory. It’s very likely that many of them were motivated by subclinical memory problems to begin with. Also curious is why this just published six-week study started six years ago.
Design:
Six-week randomized, double-blind, placebo-controlled, parallel-group trial.
Dosage:
The dosage for ginkgo was determined by following the manufacturer’s label instructions: 1 tablet (40 mg) 3 times a day, with meals. The placebo group took lactose-filled, gelatin capsules of similar appearance and on the same schedule as the ginkgo group.
Comment:
Ginkgo is 1 “tablet” 3 times a day, and the placebo is a lactose-filled gelatin “capsule” of similar appearance. Since when does a lactose-filled, gelatin capsule (white) look like a tablet (brown)? And the people that gave the patients the pills/capsules, and also counted untaken pills/capsules to measure compliance, were the evaluators. A double-blind test means that neither the participants nor the examiners should be able to tell the active compound from the placebo.
Wonder how hard it is to tell a white capsule from a brown tablet?
Also, 120 mg. of ginkgo is a very low dosage, which would usually take more than six weeks to produce any dramatic effect.
Numerous studies have already shown that ginkgo requires much higher doses than 120 mg a day to provide significant benefits within days or weeks.
The study subjects should have been given higher doses for a longer period of time.
The thing we wonder most about is why the researchers didn’t obtain the ginkgo directly from the manufacturer. They had grants funding this research. Did they ask the ginkgo manufacturer (Boehringer Ingelheim Pharmaceuticals) for the tablets and they refused? If not, why didn’t they get it from them? Did the researchers just go to the supermarket and buy the ginkgo off the shelf? The study utilized a lot of ginkgo, which means it would have cost a lot of money; where did they get the product? Also BI Pharm could have supplied them with real placebo tablets identical to the ginkgo. It seems that they didn’t ask and instead used capsules as a placebo in a study using tablets. Seems unbelievable.
Quality control:
In the exact words of the JAMA article: “The issue of quality control has also been raised as a potential source of variance in studies using over-the-counter compounds. One limitation of the present study is that we did not analyze the content of the ginkgo used in this study. However, the manufacturer claims that ginkgo “is processed under strict guidelines . . . ensured through extensive quality control.” ”
Comment:
This is the most unscientific part of the article. They should have, of course, named lot numbers of the product they used, and independently confirmed the certificates of analysis they obtained from the manufacturer for active ingredients. Can you imagine going through all the trouble of designing, funding, and carrying out this study…all the time knowing of quality control problems with over-the-counter supplements…and then not assuring the quality of the product??
Lastly, the product is a tablet. Maybe it was made wrong and has poor dissolution? A tablet that doesn’t dissolve quickly won’t be of any benefit, and research has already shown that many ginkgo products not only don’t contain the stated levels of active ingredients, but also don’t dissolve properly. Just this quality-control paragraph alone makes the study worthless. Did JAMA really print this?
Outcome:
There were no significant differences between the ginkgo and placebo groups for any outcome measure. “The results of this 6-week study indicate that ginkgo, marketed over-the-counter as a memory enhancer, did not enhance performance on standard neuropsychological tests of learning, memory, naming and verbal fluency, or attention and concentration. Moreover, there were no differences between ginkgo participants and placebo controls on subjective self-report of memory function or on global rating by spouses, friends, and relatives. These data suggest that when taken following the manufacturer’s instructions, this compound provides no measurable benefit in cognitive function to elderly adults with intact cognitive function.”
Comment:
Another flaw of the study is that both groups improved, most likely due to taking the tests only twice, once at the beginning of the study and one more time at the conclusion. If there is a drug or supplement that is stronger than experience the second time you do something, we wish we knew what it was!
With so many problems inherent in the studies design, one has to wonder why this particular study has received so much attention, both from JAMA and the media. Strangely absent in the study is any discussion of the newest research on ginkgo, which shows that ginkgo can upregulate important genes associated with stress resistance and antioxidant protection in cells. Although ginkgo is routinely touted as a “memory supplement,” its real benefits are much more far reaching. Ginkgo has shown itself to be a true “anti-aging” strategy, having the ability to increase the activity of important protective gene systems in cells, prevent mitochondrial degeneration (thought to be a major cause of aging) and extend lifespan in animals. To throw out decades of impressive research on ginkgo biloba extract because of one poorly designed study would certainly not be smart. Ginkgo may not make you a genius in 6 weeks, but to say it is worthless is not only wrong, it is intellectually dishonest and contrary to the facts.