Ginkgo Biloba Not a Wonder Drug, After All
A well-designed study shows that the popular Chinese herb does not protect against Alzheimer’s. Will anyone listen?
Ask anyone knows who’s ever taken echinacea for a cold, had their chakras balanced by a Reiki healer, put their herbalist on speed dial, or watched the Man burn on the Playa: ginkgo biloba is as good as brain food.
Proponents in the United States and Europe, where ginkgo is massively popular, have long argued that the herb improves circulation, combats dementia, and protects cells with its antioxidants. Even the Mayo Clinic’s online reference cites “promising early evidence” of ginkgo’s efficacy against everything from altitude sickness and PMS to macular degeneration.
The Chinese herb is derived from one of the oldest tree species in the world—a “living fossil,” to borrow Darwin’s term—and has been used in traditional medicine for thousands of years. A 17th century German botanist discovered the plant growing in Japanese monasteries and introduced it to the West. Goethe wrote a poem to his ginkgo tree, and Frank Lloyd Wright had one planted in his front yard. It’s said that a ginkgo tree sprouted from the ashes at Hiroshima.
Beautiful and resilient, then, is ginkgo—but not efficacious. According to a study by French researchers that appears this month in The Lancet, the popular alternative medicine does nothing to prevent Alzheimer’s disease in the elderly.
Clinical evidence has been mounting for several years, indicating that claims for the herb’s astounding health benefits are over-hyped. A 2008 study supported by the NIH’s National Center for Complementary and Alternative Medicine followed 3,000 patients over the age of 75. Half took 240 milligrams of ginkgo daily, while their peers took a placebo. After six years, the groups had identical rates of dementia and cognitive decline—in short, the herbal supplement offered no protection. Nor was it shown to lower blood pressure, prevent heart attacks or strokes, or ward off cancer.
The recent Lancet study draws much the same conclusion. Utilizing a randomized, placebo-controlled, double-blind experimental design—often described as the gold standard of scientific research—the authors followed 2,800 elderly participants who had gone to their doctors with memory complaints. (That is, instead of openly recruiting volunteers, the researchers only enrolled those patients who self-reported some kind of cognitive decline.) Half of the subjects received 120 milligrams of ginkgo twice daily, and half were given a placebo. After five years of close follow-up, the incidence of Alzheimer’s disease between the two groups was not statistically different. Conclusion: among old folks with mild memory complaints, ginkgo does not slow the onset or progression of dementia.
Such science won’t do much to sway ginkgo’s true-believers. According to a 2008 NIH report (pdf), 11 percent of Americans use the herb, making it one of the best-selling natural products in the country. The placebo effect (“I’m taking this pill that is good for me, and I feel better as a result”) is a powerful one, as is confirmation bias: when we’re standing in the supplement aisle at Whole Foods, we’re more likely to remember what our best friend said (“My mother is 92 and sharp as a tack thanks to ginkgo”) than what a bunch of French scientists concluded. So be it. But don’t let mom stop going to the doctor just yet. And caveat emptor.