Herbal Preparations: Ginseng

Ginseng

Panax ginseng describes the root from two species of plants, Asian ginseng (Panax ginseng) and American gin-seng (Panax quinquefolius), popularly used for improv-ing stamina and providing a sense of well-being. The terms red and white ginseng refer to how the root is processed, not the species of origin. Red ginseng roots are steam-cured prior to drying, while white ginseng is bleached and dried. Panax ginsengs contain triterpenoid saponins called ginsenosides (also called panaxosides), of which up to 18 types are recognized as having differing and sometimes opposing pharmacological properties.

Siberian ginseng (Eleutherococcus senticosus) should not be confused with Panax ginseng. Although it belongs to the same plant family (Araliaceae), it is a much larger, more abundant, and consequently less ex-pensive plant. Like Panax ginseng, however, it is used as a tonic and adaptogen, a nonmedical term meaning that it helps the body adapt to stress in a variety of ways. Siberian ginseng does contain saponins (eleutherosides) but no ginsenosides. To date, in spite of its popularity, there is little conclusive evidence of clinical efficacy.

Mechanism of Action

Ginsenosides are thought to be the active principles in Panax ginseng root. The various subtypes can have op-posing pharmacological actions: Rg1 stimulates the cen-tral nervous system (CNS) and elevates blood pressure, while Rb1 does just the opposite. Somehow these mul-tiple ginsenoside constituents are thought to act in con-cert to provide increased stamina. In addition, these compounds have antiplatelet aggregation effects and antioxidant properties, and they may stimulate the im-mune system.

Indications

Despite the long popularity of ginseng and its evident mild stimulatory effect, there is less conclusive evidence for its clinical effectiveness than for many of the other herbs. In regard to improving cognitive function, most studies have failed to prove a consistent benefit. A recent investigation of ginseng’s effect on physical stamina found that an 8-week course of therapy failed to improve aerobic work capacity. Ginseng has been studied as a diabetic agent, with re-duced hemoglobin A1c levels and improved glucose control being documented in a small trial. Although there is some intriguing work with ginseng as a cancer preventive, there is not enough evidence to suggest its clinical use at this time.

Adverse Reactions, Contraindications, and Interactions

Ginseng is generally considered safe for nonpregnant healthy adults; however, at sufficient doses, ginseng may elevate blood pressure and cause insomnia, palpita-tions, nervousness, and tremor in susceptible individu-als. These effects are increased if caffeine or other stim-ulants are taken concurrently. Both Panax and Siberian ginsengs should definitely be avoided in any patient with poorly controlled hypertension. Dizziness, headache, diarrhea, and nausea have also been re-ported. A controversial ginseng abuse syndrome con-sisting of tremor, elevated blood pressure, insomnia, and anxiety may also occur.

Diabetic patients have had hypoglycemia on ginseng, so sugars must be monitored, and insulin or other hypo-glycemic medication dosages may have to be reduced. The use of ginseng with anticoagulants (e.g., warfarin) and antiplatelet drugs is to be avoided because of the theoret-ical risk of increased bleeding. Also, coadministration of ginseng with digoxin and MAOIs should be avoided.

Dose

Capsules of powdered root (100, 250, and 500 mg) are available, and doses range from 200 to 600 mg per day. Ginseng may also be taken as a tea or extract. A 3-month maximum treatment course followed by a 2-week break between courses has been recommended. A major concern is that many commercial preparations do not contain the quantity of herb stated on the label. In one assessment of 54 tested ginseng products, 60% showed subtherapeutic amounts of active ingredients, and 25% showed no evidence of any ginseng at all.

Conclusion

Ginseng has been popular for more than 2000 years as a tonic for improved stamina and sense of well-being, particularly in the elderly. Although subjective quality of life reports substantiate this tradition, objective evi-dence of improved cognitive function and physical stamina remains incomplete or lacking. Further studies of standardized ginseng preparations will be necessary to clarify its use in fatigue and diabetes.