Click here for more from the Brains! special issue.
Remedies designed for the infirm seldom aid the healthy, too. Donning bifocals won't turn 20/20 eyesight into X-ray vision, and wearing a hearing aid can't endow a nonmusician with the gift of perfect pitch. It's a little baffling, then, that so many consumers assume ginkgo biloba will sharpen their memories.
Reputable medical researchers generally agree that ginkgo pills and powders, extracted from an ornamental tree whose seeds smell like rancid butter, show promise for treating Alzheimer's disease and other cases of age-related dementia. But scant scientific evidence supports the notion that ginkgo can also increase mental acuity among the young and fit. Even so, Nutrition Business Journal estimates that Americans spent $109 million on ginkgo in 2005, making it the nation's best-selling herbal brain booster, ahead of such rivals as gotu kola, Bacopa monnieri, and Siberian ginseng.
Native to East Asia, the ginkgo biloba tree likely existed during the Mesozoic Era; Charles Darwin referred to it as a "living fossil." Its seeds and leaves have been part of Chinese medicine for centuries, used to treat everything from coughs to bladder infections to unwanted freckling.
Though the ginkgo biloba tree has long been appreciated by American botanists, its medicinal properties were largely unheralded in the United States until the late 1980s. The same cannot be said of Europe, however, where German pharmaceutical company Dr. Willmar Schwabe GmbH & Co. launched its first ginkgo product, an extract formally called EGb 761, more than 30 years ago. Studies had shown that ginkgo was effective at increasing blood flow, so Schwabe marketed EGb 761, known commercially as Tebonin or Rokan, as a prescription medicine for the treatment of minor circulatory ailments. In 1988 alone, West German doctors wrote 5.24 million prescriptions for EGb 761 products.
As ginkgo's popularity increased throughout the 1980s, so, too, did the medical establishment's interest in its potential uses. Some practitioners of alternative medicine hailed ginkgo as an anti-aging remedy or as an antidote to kidney yang deficiency. Based on a study of 224 patients, one Berlin doctor pronounced ginkgo inhalations as the cure for the common cold. Dementia researchers, meanwhile, speculated that increased blood flow to the brain might help counter memory loss, a hypothesis lent credence by several small-scale West German and French studies.
Harvard University chemist Elias James Corey learned of ginkgo's promise in the late 1980s, and set his research team loose to synthesize ginkgo's active ingredient, ginkgolide B. They hoped the compound, once properly studied, could help treat toxic shock, asthma, and Alzheimer's disease. When Corey won the Nobel Prize in chemistry in 1990 for his work on organic synthesis, he name-checked ginkgolide B in his Nobel lecture, though nothing he said could be construed as an endorsement of its benefits.
Nevertheless, Corey's shout-out was a boon to Schwabe, which was just starting to market EGb 761 in the United States. Once relegated to obscure health-food stores, ginkgo broke mainstream. Schwabe first supplied EGb 761 to Nature's Way, an herbal products company based in Springville, Utah. (Utah is to supplements what Silicon Valley is to computers; Mormons are unusually keen on herbal remedies, thanks to Joseph Smith's doubts about conventional medicine.) Nature's Way sold EGb 761 as Ginkgold, the "World's #1 Selling Ginkgo." Though Ginkgold's packaging listed other benefits like its ability to reduce blood viscosity and protect against free radicals, the bold type first and foremost proclaimed it a mind sharpener. This marketing angle resonated with early 1990s health-food consumers, who were then obsessed with smart drinks and nootropics.
Virtually no peer-reviewed evidence supported Ginkgold's assertion that it could enhance memory in the otherwise healthy. But ginkgo's success in Europe, paired with Corey's inadvertent seal of approval, was enough to convince many consumers of the supplement's value. And since ginkgo was marketed as an over-the-counter supplement in the United States, the memory claim didn't need to be evaluated by the Food and Drug Administration. According to Nature's Way, Ginkgold would go on to outsell all other ginkgo biloba supplements combined in the United States. Schwabe was able to take a more direct roll in ginkgo's stateside sales starting in 1992, when it acquired a financial stake in Nature's Way; three years later, it obtained an American patent for EGb 761.
Meanwhile, clinical researchers (many funded by Schwabe) remained excited by ginkgo's potential in the fight against dementia. In 1997, a Schwabe-sponsored study published in the Journal of the American Medical Association concluded that EGb 761 "appears capable of stabilizing and, in a substantial number of cases, improving the cognitive performance and the social functioning of demented patients for 6 months to 1 year."
The 1997 JAMA study was manna for the herbal supplements industry. The active ingredient in Ginkgold had, as the product's packaging now states, been "clinically proven." But EGb 761 had not been shown to improve mental functioning in healthy adults—only in elderly "demented" adults. This significant detail was conveniently elided in Ginkgold's marketing materials, as well as those of its competitors (many of which use as little genuine ginkgo as possible).
A 1991 French study found some positive effects among healthy young females, but it involved only 12 test subjects. Other studies using more volunteers offered inconsistent results—sometimes ginkgo improved memory very slightly, but the effects inexplicably faded in and out. A British researcher noticed that rats developed more brain receptors after ingesting ginkgo, but his findings "failed to meet the mathematical test for statistical significance."
In 2002, a long-anticipated paper appeared in JAMA titled "Ginkgo for memory enhancement: a randomized controlled trial." This Williams College study, sponsored by the National Institute on Aging rather than Schwabe, examined the effects of ginkgo consumption on healthy volunteers older than 60. The conclusion, now cited in the National Institutes of Health's ginkgo fact sheet, said: "When taken following the manufacturer's instructions, ginkgo provides no measurable benefit in memory or related cognitive function to adults with healthy cognitive function."
The impact of this seemingly damning assessment, however, was ameliorated by the almost simultaneous publication of a Schwabe-sponsored study in the less prestigious Human Psychopharmacology. This rival study, conducted at Jerry Falwell's Liberty University, was rejected by JAMA, and came to a very different—if not exactly sweeping—conclusion: There was ample evidence to support "the potential efficacy of Ginkgo biloba EGb 761 in enhancing certain neuropsychological/memory processes of cognitively intact older adults, 60 years of age and over." The two studies canceled each other out in the court of public opinion; ginkgo sales remained strong.
Conflicting views of ginkgo's memory-enhacing properties are likely inevitable, since it's difficult to measure mental acuity: Every study must rely to some extent on volunteers' impressions as to whether their memories have improved. Analyze enough small sets of such subjective data and you're bound to find evidence to support either position. And if you come down a skeptic, be careful—Schwabe recently sued an Australian consumer watchdog to prevent it from publishing a report critical of EGb 761.
A large-scale, multicenter, multiyear study might clear things up, but no one appears interested in funding such a massive effort. The National Center for Complementary and Alternative Medicine is in the midst of a clinical trial involving 3,000 Alzheimer's patients, but this obviously has no bearing on whether ginkgo can help the healthy.
Regardless, herbal companies will continue to advertise their ginkgo supplements with such watery, asterisked statements as, "May help to support mental sharpness." Starbucks, of course, could reasonably make the same claim.
TODAY IN SLATE
More Than Scottish Pride
Scotland’s referendum isn’t about nationalism. It’s about a system that failed, and a new generation looking to take a chance on itself.
What Charles Barkley Gets Wrong About Corporal Punishment and Black Culture
Why Greenland’s “Dark Snow” Should Worry You
Three Talented Actresses in Three Terrible New Shows
Why Do Some People See the Virgin Mary in Grilled Cheese?
The science that explains the human need to find meaning in coincidences.
Happy Constitution Day!
Too bad it’s almost certainly unconstitutional.