Americans are obsessed with herbal supplements. A national survey conducted in 2007 found that almost 18 percent of the population uses some kind of herbal supplement, making this once niche industry a billion dollar mainstay. But although we often place our confidence and our cash in these bottles, what we’re actually getting is anyone’s guess. Unlike prescription and over-the-counter medicines, supplements do not go through safety or efficacy trials before they go to market and the claims on the front are often without warrant. Some herbs have been found to contain high levels of heavy metals, including lead and mercury. And some herbs, like ephedra, are dangerous on their own.
Despite the risks, we still spend the money. But should we? I looked at some of the popular herbs on the market to see what science says about their efficacy.
Echinacea is a plant whose parts are used, either fresh or dried, in everything from teas to pills. It is usually claimed to treat or prevent colds, flues, and to help the immune system.
There are conflicting results regarding whether Echinacea does what it claims. One of the best types of studies—a randomized, double-blind, placebo-controlled trial—looked at dried, encapsulated whole plant Echinacea in treating the common cold. Compared to a placebo, the authors of the study found that unrefined Echinacea provided no detectable benefit (or harm) in adults who had the cold. However, a meta-analysis, which looked at fourteen studies of Echinacea in the treatment and prevention of colds, found that it did shorten duration and had some effect in cold prevention.
According to the National Center for Complimentary and Alternative Medicine (NCCAM), a research organization run by the National Institutes of Health, most studies to date show that Echinacea does not appear to prevent colds or other infections. Research is still being done to determine what, if any, effects Echinacea has on the immune system.
Although Echinacea appears to be safe, some people have experienced allergic reactions to it, especially if they are prone to allergies from plants in the daisy family. People with autoimmune disease may also want to avoid the herb.
Ginkgo has been claimed to be useful for a variety of conditions, but many people take it believing it will help with memory or age-related mental decline. However, most research proves no evidence of this benefit.
One study, called the Ginkgo Evaluation of Memory study, had 3000 elderly volunteers take 240 milligrams of Ginkgo daily. They were followed for about six years. The researchers found that Ginkgo was ineffective in lowering the incidence of Alzheimer’s and dementia in the elderly. Another study sponsored by the National Institute of Aging found that among 200 adults over sixty, Ginkgo did not improve memory.
The most comprehensive look at Ginkgo was done with a systematic review of the literature done by the Cochrane Database and published in 2009. By culling and analyzing the studies, the researchers concluded that the evidence showing Ginkgo as a preventative for dementia or cognitive impairment is inconsistent and unreliable.
Because of its anti-clotting effects, Ginkgo may be useful in preventing claudication (pain in legs due to lack of blood flow), but it could also increase the risk of bleeding.
St. John’s Wort
St. John’s Wort is a weed that some believe helps with depression and other mental disorders. Although many of the studies have used different herb dosings and preparations, the majority of them have been favorable.
A Cochrane Systematic Review found that the plant extract was effective in treating mild to moderate depressive disorders. Furthermore, they also found that there were fewer side effects with the herb than with traditional antidepressants.
St. John’s Wort does interact with a variety of medications (including other antidepressants, anticoagulants, and birth control pills) so it may not be for everyone. And because it’s unregulated, you aren’t quite sure what you’re getting when you buy it.
There are three types of ginseng and not all of them contain the same compounds. Likewise, ginseng formulations use different parts of the root, stem, or leaf. Ginseng is usually sold as an herb that increases energy, mood, athletic skills, and sometimes immunity; it is also sometimes taken for diabetes.
It’s tough to come to a conclusion of the benefits or drawbacks on ginseng because many of the studies using it were small and poorly designed. Only a few large clinical trials have been conducted and most of these have not substantiated the claims made for ginseng. There is some evidence showing that ginseng can boost the immune system and some evidence indicating that Asian ginseng may lower blood glucose. However, with the variety of products and formulations on the market, it’s tough to know which type does what.
The root and rhizome of kava is used in drinks, extracts, capsules, and pills. It is thought to help people fall asleep and has been used as an anesthesia and for anxiety.
Scientific research shows that kava is more effective than a placebo in relieving anxiety, but it has not been proven for other uses. However, the FDA has issued a warning that using kava can increase the risk of severe liver damage, including liver failure and hepatitis.
Because safety is only assessed after a product goes to market, taking herbal supplements does come with risks. Although the FDA is beginning to oversee the manufacturing of dietary supplements, the process isn’t complete, and they mainly do post-market safety surveillance, which doesn’t ensure that the contents in the bottle reflect what’s on the label. Since the formulations vary, it’s tough to know what dosage, plant part, or amount you’re getting. And although they are “natural,” they can still interact with other medications. The NCAAM recommends asking a health care provider before taking supplements and doing research on the herb before your buy. You can also look for the U.S. Pharmacopeia’s seal, which shows that the supplement has met certain standards. Although there might be great promise in some herbal treatments, for now, it’s buyer beware.