Why Do So Many People Overestimate the Benefits of Herbal Medicines?
There is no denying that many medicines have their beginnings in traditional medicines. Tales of the healing properties of Chinese herbal medicines or plant treatments used by Native American centuries ago abound. Hundreds of years ago, people knew that chewing the root of the bark of a willow tree relieved their pain. In the 1800s, salicylic was identified as the active component in willow bark and, in 1899, scientists at Bayer synthesized a new form of salicylic acid called acetylsalicylic acid, more commonly known today as aspirin. This is not an isolated example.
The modern drug industry may owe its roots to early traditional medicine and certainly the end goal is the same now as it was hundreds of years ago. But the continued grip of herbal medicines on the general population is astounding. Some weeks ago, Natalie Singer in The New York Times (August 28) reported that last year in the US sales of dietary supplements purported to be used for health benefits came to $28.1 billion, a jump from $21.3 billion in 2005. Consumers of these products are driven to them because of the expectation that natural products are inherently safer than medicines derived from drug companies. Furthermore, there is the belief that centuries of use ensure efficacy. However, studies are showing that this is not always true.
Ginkgo biloba is marketed as an herbal medicine that enhances memory, and it may be the most wideIy consumed herbal treatment used to prevent age-related cognitive decline. Its popularity is attested to by its US sales which exceed $250 million annually. In 2008, the Journal of the American Medical Association published the initial results of the Gingko Evaluation of Memory (GEM) trial (JAMA, 300, 2253 – 2262), a randomized, double-blind, placebo controlled clinical trial designed to test Ginkgo biloba for preventing dementia. GEM was conducted in five academic medical centers in the US between 2000 and 2008 with 3069 volunteers aged 75 or older with normal cognition or mild cognitive impairment. Half of this population received a standardized extract of Ginkgo biloba and half received a placebo; they were followed for an average of 6.1 years. At the end of this time, there was no statistical significance in the occurrence of either dementia or Alzheimer’s disease between the two groups. In other words, Ginkgo biloba had no beneficial effect.
Saw palmetto is extracted from the fruit of Serenoa repens. Native Americans use the saw palmetto berries to treat urinary problems and it has grown popular among older men as a treatment for benign prostatic hyperplasia (BPH). In 2006, the results of the Saw Palmetto Treatment for Enlarged Prostates (STEP) trial were published (New England Journal of Medicine, 354: 557 – 566). This was another multicenter double-blind, randomized, placebo controlled trial comparing 160 mg twice a day of saw palmetto vs. a placebo. Despite looking at a variety of parameters (prostate size, residual volume after voiding, PSA score or quality of life), after one year, there was no difference between the results of saw palmetto and placebo. If this wasn’t sufficient, the results of yet another trial, this one published recently in JAMA (306: 1344 – 1350, September 28, 2011), showed that doubling and then tripling the dose used in the STEP trial for two years also had no effect. Saw palmetto is no more effective than placebo in treating BPH.
One may ask: what’s the harm? These herbal extracts aren’t toxic, and so people should be free to take whatever they’d like. Maybe taking these herbal medicines gives them peace of mind. However, because herbal drugs aren’t nearly as well studied as prescription drugs, there could be issues with them that are unrecognized. For example, does taking either Ginkgo biloba or saw palmetto interfere with the disposition of other medications that one is taking? This idea isn’t farfetched. It is known, for example, that St. John’s wort, a controversial herbal medicine taken by people to treat their depression, limits the effectiveness of a variety of medications, including antiviral agents, birth control pills and some anticancer medications.
If a person wants to take herbal medications, that’s his or her personal choice. But patients should be aware that these medications haven’t been subjected to the rigorous FDA scrutiny that all prescription medicines must receive. Buyer beware.