Ginseng (Panax ginseng) has a long history in Traditional Chinese Medicine. Panax is based on the Greek word meaning ‘all healing’ and this names highlights the usefulness of ginseng as a restorative herb. Like roseroot (Rhodiola rosea), ginseng is classed as an adaptogenic herb, making it particularly useful against the symptoms of chronic and overwhelming stress. As chronic stress may be a cause of depression, the adaptogenic properties of ginseng may give it particular useful properties against the development of mild to moderate depression. As exercise is also a form of stress, this explains the interest and use of ginseng by athletes. It is known for example that too much exercise can lead to the overtraining syndrome, and one of the symptoms of this syndrome is a mild depression. Ginseng may be able to delay the onset of the overtraining syndrome by counteracting the exercise induced stress. Based on this traditional use ginseng has become a popular herb to treat stress in Western nations.
Ginseng is a slow growing perennial plant belonging to the Araliaceae family. Panax ginseng is native to Asia. It is the fleshy root of the ginseng plant that is used medicinally. The active ingredients in ginseng are thought to be a group of chemicals called the ginsenosides (also called panaxosides). Ginsenosides are a group of diverse chemicals belonging to the triterpene saponin group. These chemicals have a structure somewhat similar to the steroid hormones synthesised by animals such as testosterone and oestrogen. To this basic steroid ring structure is then added various sugar molecules in different configurations. This variation produces a range of over 30 ginsenosides that have been isolated to date, with perhaps the most studied and recognised being ginsenoside Rb1. Although certain ginsenosides may have more activity in humans and animals compared to others, it is likely that the entire range of ginsenosides contributes to the overall adaptogenic properties of ginseng.
A number of studies have investigated the effects of ginseng supplements on the overall quality of life of the participants. This is of interest in the treatment of depression because overall quality of life is one things that has been shown to deteriorate in those suffering from depression. One group of researchers reviewed a number of studies that had been published previously to assess the impact of ginseng on quality of life. The review showed that in nearly every study, some aspect of quality of life was improved through supplementation with ginseng. For example, in one study ginseng supplements significantly improved depression, hot flushes, well-being and overall health compared to the placebo in postmenopausal women. In another study, ginseng significantly improved depressive symptoms, vitality, alertness, relaxation, appetite and self-confidence in middle aged healthy individuals. These studies involved supplementation with a dose of between 80 and 400 mg of ginseng and the study length ranged from 2 to 9 months.
The actual content of the ginsenosides in the ginseng plants is dependent on a number of factors including the age of the plant, the growing conditions, the part of the plant used, the harvest season and the extraction process. In the ginseng plant the ginsenosides appear to act as natural defence mechanisms against insect and microbial attack. Plants that are exposed to more environmental stress may therefore accumulate greater concentrations of ginsenosides. The ginsenoside content of ginseng plants is greatest when the plant reaches 6 years of age. Standardised extracts of ginseng are available commercially including G115 which contains 4 % ginsenosides, and NAGE which contains 10 % ginsenosides. The actual ginsenoside content of these standardised extracts is slightly different, but it is not clear how this affects the adaptogenic properties of the extract.
The effects of ginseng supplements have also been assessed in patients with preexisting health complaints. For example, in one study, the effects of 8 weeks of supplementation with 100 or 200 mg of ginseng were investigated in patients with type 2 diabetes. Both doses of ginseng caused significant elevations in the mood, vigor, well being and the performance of mental tasks performed by the subjects. In addition, the ginseng had the added benefit of improving blood sugar control and reducing the body weight of the subjects. At the 200 mg doses of ginseng there was also an improvement in physical activity and reduced the amount of glycated haemoglobin in the patients. In animal studies, individual ginsenosides were shown to produce antidepressant activity equivalent to that of the selective serotonin reuptake inhibitor antidepressant drug fluoxetine. The ginseng, but not fluoxetine, also decreased free radical damage in the brain and reduced levels of the stress hormone corticosterone.
Ginsenosides may exert some of their mood enhancing effects through their ability to protect neurones in the brain. This may relate to the ability of ginsenosides to inhibit the over release of nitric oxide and glutamate from neurones. In excessive amounts both nitric oxide and glutamate may be neurotoxins and so through inhibition of their release, ginsenosides may protect neurones from damage. There is also a line of evidence that suggests that ginsenosides are able to inhibit free radical production and in this way may have a general antioxidant effect that protects from lipid peroxidation in the brain. Ginsenosides may also be able to influence the blood flow to the brain, via their ability to regulate nitric oxide. In addition, some evidence suggests that ginsenosides are able to increase energy metabolism in the brain. Another way ginsenosides may protect the brain is through an ability to inhibit the release of stress hormones from the hypothalamus. There is also evidence that ginsenosides are able to increase the levels of dopamine, noradrenaline and serotonin in particular parts of the brain. Therefore ginsenosides from ginseng may, through a number of mechanisms, have a general beneficial effect on the chemistry of the brain, that improves its efficiency and overall function.
Perhaps the best known effect of ginseng is its ability to inhibit fatigue. The antifatigue effects of ginseng are of particular interest to athletes, but non-athletes can also benefit from these effects. Many of the studies involving the antifatigue effects of ginseng have been performed on animals. Rodents for example experience a significant increase in the time to exhaustion and a significant decrease in the release of stress hormones when given ginseng. That ginseng can delay fatigue and decrease stress hormone release may explain its mood enhancing effects as fatigue is clearly a cause of a depression in mood. While animals are forced to endure swim tests and treadmill running, humans metaphorically perform these tasks in the pursuit of their daily tasks, and physical exhaustion is a real problems in the modern World. Increasing the capacity to deal with such chronic fatigue may make ginseng particularly useful at increasing the resistance of an individual to the rigours of daily living, and thereby improve the quality of their life.
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