The active components in Panax and American ginseng are thought to be a family of triterpenoid saponins that are collectively referred to as “ginsenosides.” In general, most of the top-quality ginseng products, whether whole root or extract, are standardized for ginsenoside content. The active components in Siberian ginseng are considered to be a group of related compounds called “eleutherosides.”
It has been theorized that ginseng’s action in the body is due to its interaction within the hypothalamic-pituitary axis to balance secretion of adrenal corticotropic hormone (ACTH). ACTH has the ability to bind directly to brain cells and can affect a variety of stress-related processes in the body. These behaviors might include motivation, vitality, performance, and arousal.
In a widely cited study of student nurses on night duty, 1200mg of Panax ginseng appeared to improve general indices of stress and mood disturbances. Levels of free fatty acids, testosterone, and blood sugar, which were all elevated by night work, were significantly reduced to those levels observed under day work. In another study, 2,700mg/day of Panax ginseng was able to reduce blood sugar levels and insulin requirements in a group of diabetic subjects following three months of supplementation.
One study on the effects of 200mg/day of Panax ginseng extract for 12 weeks showed improvements over baseline values of mental performance — attention, mental processing, logical deduction, motor function, and reaction time.
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Over a period of several decades, German and Soviet researchers have studied the effects of Panax ginseng extract, typically standardized to 4 percent ginsenosides, on the performance of athletes. One study compared 200mg/day of Panax ginseng extract in 14 highly trained male athletes versus a placebo. The ginseng group showed an increase in its maximum oxygen uptake when compared to the placebo group, as well as a statistically significant improvement in recovery time and lower serum lactate values.
Other studies in various groups of young athletes have shown Panax ginseng extract to provide statistically significant improvements in performance measures such as forced vital capacity and maximum breathing capacity as compared to the placebo groups.
Unfortunately, the scientific evidence for ginseng is far from proven. For every study showing a positive benefit in terms of energy levels and/or physical or mental performance, there is at least one other study showing no benefits. Part of the discrepancy in results from well-controlled studies may have to do with differences between the ginseng extracts used in various studies (non-standardized extracts with unknown quantities of active components).