Like Asian ginseng, American ginseng is a light tan, gnarled root that often looks like a human body with stringy shoots for arms and legs. Native Americans used the root as a stimulant and to treat headaches, fever, indigestion, and infertility. Ginseng remains one of the most popular herbs in the United States.
Ginseng is sometimes called an "adaptogen," an herb that helps the body deal with various kinds of stress, although there is no scientific evidence to prove the benefit of adaptogens.
Most studies have used Panax ginseng (Asian ginseng). There is some evidence that Panax ginseng may help boost the immune system, reduce risk of cancer, and improve mental performance and well being. Laboratory studies in animals have found that American ginseng is effective in boosting the immune system, and as an antioxidant. Other studies show that American ginseng might have therapeutic potential for inflammatory diseases. Research on American ginseng has focused on a number of conditions, some of which are described below.
Several human studies found that American ginseng lowered blood sugar levels in people with type 2 diabetes. The effect was seen both on fasting blood sugar and on postprandial (after eating) glucose levels. One study found that people with type 2 diabetes who took American ginseng before or together with a high sugar drink experienced less of an increase in blood glucose levels. However, more research is needed.
One study using mice found that the American ginseng berry was more effective at lowering blood sugar levels than the root.
American ginseng has been shown to inhibit tumor growth. In one laboratory study on colorectal cancer cells, researchers found that American ginseng possessed powerful anti-cancer properties.
Colds and flu
In two studies, people who took a specific product called Cold FX for 4 months got fewer colds than people who took a placebo, and those who got colds found their symptoms did not last as long compared to people who took a placebo.
Attention deficit hyperactivity disorder (ADHD)
One preliminary study suggests that American ginseng, in combination with ginkgo (Ginkgo biloba), may help treat ADHD. More research is needed.
Immune system enhancement
Some scientists believe American ginseng enhances the immune system. In theory, this improvement in immune function could help the body fight off infection and disease. Several clinical studies have shown that American ginseng does boost the performance of cells playing a role in immunity.