There are currently 11 known varieties of ginseng and two main types: Korean or Asian ginseng (Panax ginseng) and American ginseng (P. quinquefolius). The use of Asian ginseng in traditional Chinese medicine is well-documented. According to an ancient text, Asian ginseng has properties that boost longevity, enlighten the mind, and increase wisdom. The ancient Chinese valued the herb more than gold and reserved its use for treating royalty.
The existence of an American variety was not discovered until the early 1700s, when a Jesuit priest found that it grows wild in America and is used by native Americans for medicine. By the end of the 19th century, the herb was formally introduced in the West, and it has since grown in popularity as an alternative medicine. In terms of potency, however, Asian ginseng is considered to be more stimulating than American ginseng.
Today, ginseng is not only (still) widely used, it is also extensively studied. Numerous studies have linked various benefits to different varieties of ginseng. These health benefits include:
Ginseng has also been recently linked to the improvement of liver functions and the treatment of liver disorders, such as acute or chronic liver toxicity, hepatitis, liver fibrosis and cirrhosis, and hepatocellular carcinoma or liver cancer.
The biological activities and therapeutic benefits of ginseng are attributed mainly to a class of plant compounds known as saponins. Saponins are active phytochemicals often found in vegetables like peas and soybeans, as well as in various herbs. Saponins are known to have antioxidant properties, reduce bone loss and blood cholesterol, lower the risk of cancer, and boost immunity.
Ginseng saponins are commonly known as ginsenosides. To date, more than 40 different ginsenosides have been isolated from the roots of ginseng plants. The six major saponins found in ginseng, namely ginsenosides Rb1, Rb2, Rc, Rd, Re, and Rg1, account for more than 90 percent of the total ginsenoside content of Asian ginseng root and more than 70 percent of the total ginsenoside content of American ginseng root. These compounds are often used to determine the quality of ginseng medications and products. (Related: Ginseng phytonutrient Ginsenoside Rg3 effective against hepatocellular carcinoma.)
According to a study, ginsenoside Rd has an inhibitory effect on liver cancer cells. In particular, ginsenoside Rd has been shown to prevent tumor invasion and metastasis of human hepatocellular carcinoma (HepG2). Researchers discovered that ginsenoside Rd exerts its effects by reducing the expression of metalloproteinases, which are enzymes that promote cancer cell metastasis by degrading the extracellular matrix. This degradation facilitates angiogenesis -- the formation of new blood vessels -- and tumor invasion. Ginsenoside Rd also blocks important signaling pathways that are necessary for cancer cell migration and proliferation in new sites.
Because of these activities, researchers believe that ginsenoside Rd from both American and Asian ginseng may be useful for the development of novel and natural chemotherapeutic agents that can treat malignant cancers.