American Ginseng (Panax Quinquefolius)
The American ginseng plant, Panax quinquefolius, is similar in appearance and is in the same botanic genus as Asian ginseng (panax ginseng). First described in the early 18th century in Eastern Canada, P. quinquefolius was primarily harvested for export to China. American ginseng is also referred to as North American, Canadian, or Wisconsin ginseng, referring to primary areas of harvest or cultivation, although it is now grown in many areas of the world. The root is used medicinally.
Uses and Benefits
Ginsengs are marketed in the U.S. to boost energy, relieve stress, improve concentration, and enhance physical or cognitive performance. Most ginsengs are believed to act as general restoratives, tonics, or adaptogens, which have nonspecific strengthening properties to restore the body's balance, enhance stamina, and increase resistance to stress and disease.
In traditional Chinese medicine (TCM), Asian and American ginsengs are used to restore vital energy in the body. However, American ginseng is considered to have more cooling or calming qualities, as opposed to Asian ginseng's more heating or stimulating properties. According to TCM theory, American ginseng is used to calm the ailing respiratory or digestive systems and as therapy for diabetes or "thirsty" syndromes, and may be preferred in warmer climates.
Native Americans traditionally employed American ginseng to help with childbirth and fertility and to strengthen mental powers, and for a variety of ailments such as respiratory disorders, headaches, and fevers.
There are few controlled clinical trials using American ginseng products. In one randomized, double-blind, placebo-controlled crossover study of eight athletic volunteers, a noncommercial American ginseng extract in a daily dose of 8 - 16 mg/kg for 7 days failed to enhance physical performance as measured by a cycle ergometer. There were no significant differences compared to placebo in any of the outcome measures, which included oxygen uptake, heart rate, time to exhaustion, lactate and glucose concentrations, and rating of perceived exertion.
In a series of randomized, single-blind, placebo-controlled studies by the same investigators, a single dose of American ginseng was found to reduce post-prandial glycemia by about 10-20%. Effects were not found to be dose dependent. In healthy subjects, 1-3 g doses reduced glycemia when given at least 40 minutes before a glucose load. In type-II diabetics, 3-9 g doses were tested and found to reduce glycemia when given with, or up to 2 hours prior to, a glucose load.
No significant adverse effects have been reported in the few clinical trials, and there are no case reports of clinical toxicities. Due to similar chemical constituents, American ginseng has the potential to cause any of the side effects possible with Asian ginseng, which appear to be uncommon and idiosyncratic.
Side Effects and Interactions: No drug interactions are recognized.
One American ginseng product has been shown to mildly blunt the hyperglycemic effect of food; this may theoretically be detrimental in a tightly controlled or labile diabetic. Unlike Asian ginseng products, adulteration or contamination of American ginseng has not yet been reported. Safety has not been established during pregnancy or breast feeding.
Preparations & Doses:
American ginseng is available in multiple forms, from whole root products to a variety of more concentrated formulations and extracts in capsules, tablets, liquids, teas, and foods. The crude root is usually taken in doses of 1-2 g/day, but up to 9 g or more is used in traditional Chinese medicine. Many formulations contain concentrated extracts or preparations standardized to ginsenosides, usually as 100-200 mg of extract per dose.
American ginseng, like Asian and Siberian ginseng, is traditionally used as a tonic or adaptogen to enhance health and combat stress or disease. Few clinical trials have been conducted. In one well-designed study, American ginseng did not enhance physical performance. In another series of studies, single doses of one product mildly attenuated post-prandial glycemia; whether this effect is reproducible and beneficial for diabetics awaits chronic dosing trials. There are no well-documented adverse effects of American ginseng.