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July 2001; Volume 4;77-80
By Dónal P. O’Mathúna, PhD
Sports supplements sales amounted to $1.4 billion in the United States in 1999, or about 10% of the dietary supplement market.1 Of all the herbal remedies used by athletes, more clinical research has examined ginseng, consistently the second most popular herbal remedy sold in the United States.2 Traditional Chinese medicine (TCM) uses ginseng as an adaptogen—a substance that helps the body adapt to stressful situations and promotes general well-being.3 Ginseng is popularly believed to boost one’s energy levels, which makes it attractive to athletes hoping to improve their performances. Unfortunately, the science doesn’t live up to the sales, with studies consistently showing that ginseng does not enhance sports performance among athletes.
Ginseng exemplifies some of the complexities and difficulties surrounding herbal remedies. The term "ginseng" applies to several plant species. The ginseng of TCM is Asian, Chinese, or Korean ginseng (Panax ginseng), with American ginseng being the closely related Panax quinquefolius. Several other Panax species are used in Japanese, Vietnamese, San-chi, and Tien-chan ginseng.4 Siberian ginseng (Eleutherococcus senticosus) is related distantly to the Panax species, and Brazilian ginseng is botanically unrelated (Pfaffia paniculata).5
The active ingredients in Asian and American ginseng are a group of about 30 steroidal glycosides called ginsenosides.4 However, the ginsenoside levels vary according to species, season harvested, age of the plant, soil, and part of the root used; in 20 American ginseng plants harvested from a 1 square-meter area, the ginsenoside content varied more than twofold.6 Traditionally, Asian ginseng is harvested after at least five years of growth, at which time the roots typically contain 1-2% ginsenosides.3 Siberian ginseng contains no ginsenosides, but instead contains other steroidal glycosides called eleutherocides.
Mechanism of Action
Several mechanisms of action have been proposed for ginseng. In TCM, ginseng is believed to restore a balanced flow of Qi, or life energy. Animal studies have shown that isolated ginsenosides can stimulate or depress the central nervous system; increase production of corticotrophin and cortisol; stimulate synthesis of DNA, RNA, and protein; and act as immunostimulants or antioxidants.3 No consensus exists concerning whether any or all of these actions contribute to ginseng’s effects on athletes.
Asian and Siberian ginseng are most commonly promoted as beneficial for athletes. Asian ginseng has been examined in clinical trials with athletes since the early 1970s. In the early 1980s, Dr. Imre Forgo published five small studies in Germany with elite athletes.7 Those taking two 100 mg capsules daily of a standardized product, G115® (Ginsana®, Pharmaton), had improved oxygen absorption, reduced blood lactate levels, reduced heart rates, and improved subjective feelings of physical fitness.8 However, some of these studies did not use control or placebo groups, and used indirect measures of oxygen consumption and submaximal workloads.9
Since 1990, several better-designed trials have been published,10 but nearly all report small numbers and test healthy adults of various fitness levels.
Studies conducted during the 1990s on the ergogenic effects of ginseng
|Van Schepdael11||randomized, double-blind, crossover||43 female triathletes||400 mg/d G115||10 weeks||Reduced blood lactate during second 10-week period|
|Cherdrungsi12||randomized, double- blind, four groups||41 students||150 mg bid standardized extract||8 weeks||"No clear synergistic action" between exercise and ginseng|
|Engels9||randomized, double-blind||19 healthy adult females||200 mg/d G115||8 weeks||No significant ergogenic effects|
|Engels5||randomized, double-blind||36 healthy adult males||200 or 400 mg/d G115||8 weeks||No significant ergogenic effects|
|Kolokouri13||randomized, double-blind||24 healthy adult females||400 mg/d||8 weeks||No significant ergogenic effects standardized extract|
|Engels14||randomized, double-blind||12 aerobically fit young adults||1 g/d ginseng root||60 days||No significant ergogenic effects|
|Lifton15||randomized, double- blind, crossover||11 well-trained amateur cyclists||3 g/d ginseng||13 days||No significant ergogenic effects|
|Allen16||randomized, double- blind, crossover||28 moderately fit adults||200 mg/d 7% ginsenoside standardized extract||21 days||No significant ergogenic effects|
Studies using ginseng in combination with other supplements will not be considered here. Two studies of Asian ginseng alone showed some ergogenic effects from ginseng, though neither were clearly beneficial. A randomized, double-blind, crossover study involving 43 female triathletes used 400 mg/d G115.11 Ginseng provided no exercise advantage during the first 10-week period. During the second 10-week period, those taking ginseng had significantly lower blood lactate during exercise but no performance advantage. The researcher concluded that ginseng may delay end-of-season tiredness, but cautioned that a carryover effect from the first period may have contributed to this finding. This hypothesis was not tested in this study.
In a small study of strength and fitness, 41 students were randomly assigned to four groups.12 Group 1 took a standardized ginseng extract (150 mg bid) and rode an exercise bicycle for 30 min three times a week. Group 2 exercised the same way and took a placebo. Group 3 took ginseng without exercising, and Group 4 took a placebo without exercising. After eight weeks, Group 1 had greater leg strength compared to Group 2 (P < 0.05), but nonsignificant differences in 10 measures of physiological fitness. Comparing Groups 3 and 4 (neither exercising), those taking ginseng showed significant improvements in maximal oxygen uptake, resting heart rate, and leg strength. The authors concluded there was "no clear synergistic action" between exercise and ginseng.
A number of other well-performed, similarly designed, double-blind studies confirm these conclusions and have found no significant differences between the two groups in maximum heart rate, maximum oxygen consumption, respiratory exchange rate, or total workload.5,9,13-15 For example, a randomized, double-blind, crossover trial used 28 moderately fit adults taking 200 mg of a 7% ginsenoside standardized extract.16 Subjects took ginseng or placebo for 21 days and before and afterward performed a graded exercise test on an ergometer. No significant differences were observed for VO2, exercise time, workload, heart rate, rate of perceived exertion, or blood lactate and hematocrit.
Some suggest ginseng may enhance physical performance via improved concentration, alertness, and arousal. A randomized, double-blind trial of ginseng’s psychological effects used 400 mg/d standardized ginseng extract with 112 adults (mean, 51 years).17 After eight to nine weeks, those taking ginseng had slightly faster reaction times, though statistically significant only for the 10th percentile scores and not for mean scores. Abstract thinking was significantly improved, but not memory, concentration, or well-being. Ginseng has not been beneficial in some psychological studies.18
One crossover study examined the ergogenic effect of American ginseng using an extract made for the study.19 Eight subjects of varying fitness levels were randomly assigned to either 8 mg/kg or 16 mg/kg of ginseng or placebo. After seven days subjects completed a time-to-exhaustion test on a cycle ergometer. The two ginseng groups showed no differences, so their results were combined. Time to exhaustion, oxygen consumption, respiratory exchange rate, and blood levels of lactate, free fatty acids, and glucose showed no significant differences between ginseng and placebo.
The ergogenic effects of Siberian ginseng have been studied in two controlled trials since 1990. The first randomly assigned 20 highly trained distance runners as matched pairs to 3.4 mL of an alcoholic solution of ginseng or placebo.20 Exercise tests were conducted every two weeks on a treadmill where athletes ran for 10 min at 10 km race-pace and then to exhaustion. No significant differences were found in several respiratory measurements, time to exhaustion, heart rate, or blood lactate levels.
The second Siberian ginseng study used a randomized, double-blind, crossover design with 10 highly trained male cyclists.21 Subjects took 1,200 mg Siberian ginseng or placebo for seven days prior to conducting a 120 min cycle at 60% VO2max followed by a 10 km time trial. No significant differences were found at any point between ginseng and placebo in oxygen consumption, respiratory exchange ratio, heart rate, rating of perceived exertion, or plasma lactate and glucose levels.
Adverse effects of ginseng were not reported in the clinical trials with athletes, but have been reported occasionally with other users. Adverse effects have not been reported with American ginseng, and very rarely are they reported for Siberian ginseng. However, Asian ginseng has been reported to occasionally cause mastalgia, vaginal bleeding, amenorrhea, tachycardia, edema, hypotension, palpitations, mania, decreased appetite, hyperpyrexia, pruritus, rose spots, headache, vertigo, euphoria, and neonatal death.22 The incidence of adverse effects increases when use is extended beyond three months, though estimates of the increase are not available. A "ginseng-abuse syndrome" has been proposed for the regular consumption of more than 3 g/d ginseng. The symptoms are hypertension, nervousness, sleeplessness, and diarrhea.4
The quality of ginseng products in the United States is of serious concern. One analysis found that only nine of 22 products passed a quality control test, with eight containing greater than allowed pesticide levels.23 Ginseng is not banned by the International Olympic Committee or the National Collegiate Athletic Association, but an athlete at the 1988 Seoul Olympic Games tested positive for ephedrine, which is banned. The ephedrine was traced to a ginseng product.24
Very little evidence exists here, although theoretically ginseng’s many constituents could interact with several drugs. All ginseng species potentiate caffeine’s stimulant effects, suggesting caution when taken with tea, coffee, and herbs like guarana or mate. Reports exist of Asian ginseng interfering with warfarin and other blood-thinning agents, though inconsistently. Theoretically, all ginseng species could interfere with antidiabetic agents, antipsychotic drugs, steroids, and with drugs metabolized by the cytochrome P450 enzyme system.23
Ginseng plant material is processed in several ways, leading to further variability in ginsenoside content. The roots are most commonly bleached and dried, producing "white ginseng."3 If the roots are steam-cured prior to drying, this gives "red ginseng." Teas, extracts, and tinctures (alcohol-based extracts) are available, leading to even greater variability.
In TCM, 3-9 g/d of powdered ginseng root is taken, usually combined with other herbs.3 Standardized preparations typically contain 4% ginsenosides, with 200 mg/d ginsenosides recommended. Many clinical trials used a standardized preparation called G115.
Although animal studies consistently have found exercise benefits from ginseng and ginsenosides, these studies have tended to use much higher doses than those given to humans (up to 100 times higher). A number of early human studies found significant ergogenic effects, which gave ginseng use much credibility among athletes. The Ginsana web site continues to cite these studies from the 1980s, but fails to mention that several, better-designed studies have not reproduced these results.8
The results of ginseng research are complicated by varying doses, plant species, and product formulations. Studies have been conducted for different lengths of time and used different outcome measures. However, lack of efficacy has emerged as the most consistent result. Although the research protocols may vary from how athletes use ginseng, the evidence fails to demonstrate that ginseng has any direct impact on athletic performance.
Ginseng is widely used by the general population and among athletes. Although adverse effects are relatively infrequent, the lack of direct ergogenic effect should caution athletes against taking ginseng. Some hold that ginseng offers athletes psychological benefits that enhance performance. However, these effects have not been examined in competitive situations. Athletes should beware that contaminants are found regularly in ginseng products, some of which are substances banned by sports organizations. Given the lack of efficacy, any risk of adverse effects, and the small chance of inadvertently consuming a banned substance, athletes should be discouraged from taking ginseng. Research does not support its use as an ergogenic aid.
Dr. O’Mathúna is Professor of Bioethics and Chemistry at Mount Carmel College of Nursing, Columbus, OH.
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