Panax Ginseng
DAVID KIEFER, M.D., and
TRACI PANTUSO, B.S.
University of Arizona College of Medicine, Tucson, Arizona
The herbal remedies referred to as "ginseng" are
derived from the roots of several plants. One of the most commonly used and
researched of the ginsengs is Panax ginseng, also
called Asian or Korean ginseng. The main active components of Panax ginseng are ginsenosides,
which have been shown to have a variety of beneficial effects, including
anti-inflammatory, antioxidant, and anticancer effects. Results of clinical
research studies demonstrate that Panax ginseng may
improve psychologic function, immune function, and
conditions associated with diabetes. Overall, Panax
ginseng appears to be well tolerated, although caution is advised about concomitant
use with some pharmaceuticals, such as warfarin, oral
hypoglycemic agents, insulin, and phenelzine. Panax ginseng does not appear to enhance physical
performance. Products with a standardized ginsenoside
concentration are available. (Am Fam Physician 2003;68:1539-42. Copyright© 2003 American
Herbal remedies known as "ginseng" are based
on the roots of several distinct species of plants, mainly Korean or Asian
ginseng (Panax ginseng), Siberian ginseng (Eleutherococcus senticosus), and
American ginseng (Panax quinquefolius).
All of these species are in the Araliaceae plant
family, but each has its own specific effects on the body.
Ginseng products are popularly referred to as
"tonics," a term that has been replaced by "adaptogens"
in much of the alternative medicine literature. The term "adaptogen" connotes an agent that purportedly
"increases resistance to physical, chemical, and biological stress and
builds up general vitality, including the physical and mental capacity for
work." 1(p236) Over-the-counter Panax
ginseng products include Celestial Seasonings Ginseng, Centrum Herbals Ginseng,
Korean Ginseng Extract from Nature's Way, Nature Made's Chinese Red Panax Ginseng,
Pharmaton's Ginsana, and PhytoPharmica's Ginseng Phytosome.
Panax ginseng is one of the most commonly used and highly
researched species of ginseng. This species, which is native to China, Korea,
and Russia, has been an important herbal remedy in traditional Chinese medicine
for thousands of years, where it has been used primarily as a treatment for
weakness and fatigue. 2
Pharmacology
The main active agents in Panax
ginseng are ginsenosides, which are triterpene saponins. The majority
of published research on the medicinal activity of Panax
ginseng has focused on ginsenosides. 3 These are
the compounds to which some ginseng products are now standardized.
Research reviews 2,4 postulate that extracts of Panax
ginseng affect the hypothalamus-pituitary-adrenal axis and the immune system,
which could account for many of the documented effects. Animal models and in
vitro studies mentioned in these reviews 2,4 indicate that Panax ginseng enhances phagocytosis,
natural killer cell activity, and the production of interferon; improves
physical and mental performance in mice and rats; causes vasodilation;
increases resistance to exogenous stress factors; and affects hypoglycemic
activity.
Efficacy
Panax ginseng is used primarily to improve psychologic function, exercise performance, immune
function, and conditions associated with diabetes (Table 1)
. Traditional Chinese
medicine and many current research studies 5-8 often use products that
combine ginseng with other herbal medicines or vitamins. Because of the use of
combination products and the limitations of some studies on ginseng (e.g., poor
methodologic quality, research focusing on healthy
volunteers, small sample size, unstandardized ginseng
preparations, varying doses), it is difficult to draw conclusions about some of
the clinical effects of ginseng. Many research trials have been performed on
the standardized Panax ginseng extract Ginsana (G115).
EFFECTS ON PSYCHOLOGIC FUNCTION
Trials investigating the effects of Panax ginseng on various psychologic
parameters have shown positive effects, no effects, or both. In one study 9 of 112
healthy volunteers older than 40 years, the administration of 400 mg per day of
the standardized ginseng product Gerimax for eight
weeks resulted in better and faster simple reactions and abstract thinking, but
no change in concentration, memory, or subjective experience.
The results of two small studies, 10,11 each
including about 30 young, healthy volunteers who received 200 mg of G115 daily
for eight weeks, showed improvement in certain psychomotor functions (i.e.,
better attention, processing, and auditory reaction time), social functioning,
and mental health. However, some of the effects present at the fourth week
disappeared by the eighth week. 11
A study of 384 postmenopausal women who were
randomized to receive placebo or ginseng for 16 weeks showed improvements in
three subsets of a Psychological General Well-Being index. 12 [Evidence
level A, randomized controlled trial (RCT)] In addition, a small study 7 of 20
healthy young volunteers who received a single 400-mg dose of ginseng found
improvement in cognitive performance, secondary memory performance, speed of
performing memory tasks, and accuracy of attentional
tasks. However, another study 13 showed no effect on positive affect, negative affect,
or total mood disturbance in 83 young healthy volunteers who took 200 to 400 mg
per day of G115 for eight weeks.
EFFECTS ON PHYSICAL PERFORMANCE
Most of the clinical studies investigating
the value of Panax ginseng in enhancing physical
performance have shown no clinical effect. 14 One study 15 on the
use of 200 mg per day of G115 in 19 healthy adult women showed no change in
physical work performance, energy metabolic responses, or oxygen uptake.
Similarly, a study of 31 healthy men who took
200 or 400 mg of G115 daily for eight weeks found no change in physiologic or psychologic responses to submaximal
or maximal exercise. 16 [Evidence level B, lower quality RCT] In another
study, 17 a different product standardized to 7 percent ginsenosides and administered at 200 mg per day was given
to 28 healthy young adults for 21 days. No ergogenic
effects were demonstrated, including no change in
maximal oxygen consumption, exercise time, workload, plasma lactate level, hematocrit, or heart rate.
EFFECTS ON IMMUNE SYSTEM
A study 18 of 227 healthy volunteers
demonstrated that daily administration of 100 mg of G115 for 12 weeks enhanced
the efficacy of polyvalent influenza vaccine. The patients who received ginseng
had a lower incidence of influenza and colds, higher antibody titers, and
higher natural killer cell activity levels. Another study 19 in 60
healthy volunteers showed enhanced chemotaxis, phagocytosis, increased total lymphocyte count, and
increased numbers of T helper cells in those who received G115 in a dosage of
100 mg twice daily for eight weeks. In a study of
75 patients with acute exacerbation of chronic bronchitis who
were treated with antibiotics or antibiotics plus ginseng, those in the ginseng
group showed faster bacterial clearance. 20
EFFECTS ON DIABETES
The effects of Panax
ginseng, given in a dosage of 100 or 200 mg per day for eight weeks, were
studied in 36 patients with newly diagnosed non-insulin-dependent diabetes. 21 The
study showed improved fasting blood glucose levels, elevated mood, and improved
psychophysical performance on a numbered diagram test. The 200-mg dose also
resulted in improved hemoglobin A 1C values.
ADDITIONAL USES
In 45 patients with erectile dysfunction, use
of ginseng improved erectile function, sexual desire, and intercourse satisfaction.
22
Panax ginseng also appears to have anti-cancer effects. In
a prospective cohort study 23 of 4,364 persons older than 40 years, the risk of
cancer was shown to be lower in those who used ginseng (relative risk: 0.40).
Adverse Effects, Drug Interactions, and Contraindications
Interpretation of documented adverse effects
and drug interactions can be difficult because of the variety of available
ginseng formulations, and because the exact amount of ginseng in these products
may not be identified.
Panax ginseng generally is well tolerated, and its adverse
effects are mild and reversible. 24 Associated adverse effects include nausea, diarrhea,
euphoria, insomnia, headaches, hypertension, hypotension, mastalgia,
and vaginal bleeding. 4,24,25
Panax ginseng may interact with caffeine to cause
hypertension, and it may lower blood alcohol concentrations. It also may
decrease the effectiveness of warfarin (Coumadin). Concomitant use of Panax
ginseng and the monoamine oxidase inhibitor phenelzine (Nardil) may result in
manic-like symptoms. 4,23
Contraindications to the use of Panax ginseng include high blood pressure, acute asthma,
acute infections, and nose bleeds or excessive menstruation. These effects
appear to occur primarily with high dosages or prolonged use. 26
Ginseng also causes hypoglycemic activity,
and caution should be exercised in using ginseng products in patients with
diabetes because of possible interactions with oral hypoglycemic agents and
insulin. One source 2 recommends
avoiding the use of ginseng products in children and in women who are pregnant
or lactating, until more rigorous studies prove safety in these groups.
Dosage
Most published research studies have used a
standardized Panax ginseng extract in a dosage of 200
mg per day. Other sources 2,23,27 recommend
0.5 to 2 g of dry root per day on a short-term basis, with the ginseng taken in
tea form or chewed. Capsule formulas are generally given in a dosage of 100 to
600 mg per day, usually in divided doses.
Standardization is to the ginsenoside
content, which is usually recommended to be 1.5 to 7 percent. 2 According
to one source, 28 4 percent is an important standard level.
Ginseng is commonly taken for long periods. 1,29 One source 1(p239)
recommends a two-week ginseng-free
period every two to three weeks for some persons.
The authors indicate that they do not have any conflicts of interests. Sources of funding: none reported.
The Authors
DAVID KIEFER, M.D., is a fellow in the Program in Integrative
Medicine at the University of Arizona College of
Medicine,
TRACI PANTUSO, B.S., is a volunteer at the Program in Integrative
Medicine. She graduated from