Ginseng has been used as a cure-all since ancient times (the botanical name, Panax, means "all healing" in Greek). According to ancient and medieval herbal folklore, plants that resemble human body parts have healing effects on those parts. And since ginseng's root resembles a human figure, it's said to have benefits for the whole body.
Proponents claim that ginseng acts as an "adaptogen," boosting the body's resistance to physical and mental stress, increasing energy and enhancing general well-being.
The herb is said to help prevent or treat everything from colds, diabetes, digestive problems, and menopause symptoms to poor circulation, asthma, memory problems, and even HIV infection and cancer. It's also touted as an aphrodisiac.
There are several types of ginseng. Asian ginseng (Panax ginseng C.A. Meyer)—often sold as Korean, Chinese or Panax ginseng—is grown in eastern Asia. American ginseng (Panax quinquefolius) is native to North America. Ginseng also comes as red or white ginseng, depending on how it's processed. Siberian ginseng (Eleutherococcus senticosus) is often said to have the same effects as Panax ginseng, but it is not a true ginseng. It and other similar plants may be used in products as a cheaper substitute.
Ginseng is one of the most researched herbs. It contains many active ingredients, including more than 40 different ginsenosides, thought to be the plant's main active ingredients. Studies have shown that these compounds have anti-inflammatory, antioxidant, anti-cancer and immune-modulating properties. They may also relax blood vessels, help protect the nervous system, affect hormones and improve blood sugar, among other effects.
Still, ginseng's medicinal effects remain unclear. One problem is its variability. Different types of ginseng have different compounds and biological properties, and different parts of the plant (roots, leaves, stems) also contain varying chemicals. How ginseng is processed affects its biological activity as well. Most studies on ginseng have been small or poorly designed and have used different formulations and doses of ginseng, making them hard to compare. Moreover, it's difficult to study the many vague claims. How, for instance, do you measure increased "well-being" or "vitality"?
Diabetes: Several small but well-designed studies have found that ginseng can help control blood sugar, possibly by increasing insulin production, among other mechanisms. The Natural Standard, which evaluates alternative and complementary therapies, gives ginseng a B rating (good evidence) for its effect on blood sugar in people with type 2 diabetes—but notes that its long-term effectiveness and safety are unclear. In a small new study in the journal Diabetes, however, overweight people with diabetes or poor blood sugar control did not benefit from taking Korean ginseng for 30 days.
Immunity. There's also B-grade evidence that ginseng boosts the immune system, according to the Natural Standard: A small Canadian study in 2008, for example, found that North American ginseng increased various immune markers in sedentary men who did a short bout of cycling. It's not clear, however, what practical significance this has. Preliminary studies suggest that Cold-fX, a standardized extract of North American ginseng, may help reduce the frequency, severity and duration of cold and flu symptoms—though this patented extract is different from other ginseng supplements.
Brain health: A 2008 study from South Korea found some improvement on cognitive tests in people with Alzheimer's disease who took Korean white ginseng for 12 weeks. Though some review articles also cite potential benefits on cognition, they note that there is a scarcity of good-quality data. In 2010 the Cochrane Collaboration concluded that there is "no convincing evidence of a cognitive enhancing effect of Panax ginseng" in either healthy people or those with memory problems or dementia. The Natural Standard gives ginseng a C rating (conflicting or unclear evidence) for Alzheimer's disease.
Other ginseng uses. Preliminary research, including a Brazilian study in 2007, suggests that Korean red ginseng may improve erectile dysfunction; other forms may not have this effect. Some athletes use ginseng, but studies have generally found no effect on performance. There's no convincing evidence ginseng can treat or prevent fatigue, high blood pressure, cancer or any other condition it's also touted for.
In a way, it's hard to evaluate ginseng. How it's typically studied and used in the West (as a single herb in a purified extract) is not how it's traditionally used (in its whole form and often in combination with other herbs).
Still, we can't recommend ginseng, since all we have to go on are the studies, which, overall, don't show clear or conclusive benefits. The best evidence is for its effect on blood sugar, but if you have diabetes you should not use ginseng in place of proven therapies.
In addition, ginseng may interact with anti-clotting medication as well as drugs taken to control blood sugar (such as insulin) and certain antidepressants. It should be used with caution in people with high blood pressure or those taking medications that affect blood pressure. And there can be side effects from long-term use, including anxiety, loss of appetite and insomnia.
Unless you buy the whole root, which is very expensive, you may not even be getting real ginseng. A 2010 analysis by ConsumerLab.com found that several supplements didn't have the full amount of ginseng listed on the label, and there was also great variability in ginsenosides among the products. Plus, some products were contaminated with lead and pesticides. Be aware that even if ginseng does have some "adaptogenic" or tonic-like effects, the amount in bottled beverages and other "energy" products is probably too small to make a difference.