While we agree it is important to look critically at the claims made by the nutraceutical industry, we must not lose sight of the need to hold herbal studies to the same evidence-based standards to which we hold all medical research. Therefore, we were troubled by Lazar’s conclusions (“Gingko is not a smart pill,” J Fam Pract 2002; 51:912) that “gingko is not a smart pill,” and “if you do not currently recommend gingko supplements to older patients who are worried about memory loss, do not start now.”
The purpose of the original paper by Solomon et al was to evaluate gingko in healthy elderly volunteers using standardized tests.1 Nowhere in their report did they explicate whether the intervention itself was standardized. Without this crucial information about the quality of the herbal product that is being tested, the internal validity of any botanical research cannot be judged, nor can any conclusive inferences be made.
One unfortunate result of the 1994 Dietary Supplement and Health Education Act is that what is on the label may not be what is in the bottle.2 The potency of herbal products can vary from manufacturer to manufacturer and from lot to lot, in part because of nonstandard processing and manufacturing methods, and in part due to the variability of cultivation conditions.3 Therefore, a distinction must always be made between a brand (eg, Ginkoba) and a plant (eg, Gingko biloba). Saying that something is just “gingko,” as if all gingko products are the same, is not enough.
Examples of the rigorous level of inquiry and analysis needed to conduct meaningful botanical research exist even in the case of G biloba. Interestingly enough, in the very same month that the paper by Solomon et al was published, Mix and Crews reported on a study with an identical goal.4 However, unlike the Solomon study, they used a G biloba extract known as EGb 761 that is standardized to contain 24% flavone glycosides, 6% terpene lactones, and less than 5 ppm gingkolic acids. Using 180 mg of this extract daily for 6 weeks resulted in enhancing certain neuropsychological and memory processes of cognitively intact older adults, aged 60 years and over.
So is gingko a smart pill? We would let the readers decide. What we do know is that smart conclusions depend on critical appraisal and appropriate interpretation of all the evidence available. We conclude that the question of whether to recommend gingko supplements to older patients who are worried about memory loss remains open.
Opher Caspi, MD, MA, and
Anastasia Rowland-Seymour, MD,
Program in Integrative Medicine, College of Medicine,
University of Arizona, Tucson.
E-mail: ocaspi@ahsc.arizona.edu.
Dr Lazar responds:
Ginkoba is not effective in improving memory in nondemented older adults who are worried about their memory. Other ginkgo products not studied here may have benefit.