Adaptogens or adaptogenic substances, compounds, herbs or practices refer to the pharmacological concept whereby administration results in stabilization of physiological processes and promotion of homeostasis, for example, decreased cellular sensitivity to stress. The European Medicines Agency states in a 2008 reflection paper that the concept requires additional clinical and pre-clinical research, and is therefore not accepted into current terminology.
Normal pharmacological theory supports the receptor theory of drug mechanism, and the scientific community calls into question the validity of the concept of adaptogens, while the U.S. Food and Drug Administration (FDA) and European Medicines Agency accept that the term can be used to assess traditional products.
In herbal medicine the categorization of different herbs as adaptogens is very popular, often with far-reaching claims of increasing longevity, libido and well-being. Most of the studies conducted on adaptogens were performed in the Soviet Union, Korea, and China during the 1980s. While they may be suggestive, the studies are not considered conclusive, having been criticized for various methodological flaws.
Adaptogens have been claimed to treat a wide variety of medical conditions, from fatigue to cancer. Adaptogenic effect of some herbs may occur as a result of the herb containing substances that increase the body's own response to oxidative stress, such as Gynostemma pentaphyllum wn to increase the body's innate response by increased production of superoxide dismutase (SOD).[medical citation needed]
The concept of adaptogens was originally created by pharmacologist N.V. Lazarev in 1947 to describe novel effects of dibazol 12-benzyl benzimidazol, an arterial dilator developed in France. Adaptogenesis was later applied in the former Soviet Union to describe remedies that increase the resistance of organisms to biological stress in experimental and clinical studies. According to the original definition, adaptogens are:
non-specific remedies "that increase resistance to a broad spectrum of harmful factors (stressors) of different physical, chemical and biological natures".
This definition has been updated and today adaptogens are conceptualized as a:
"new class of metabolic regulators (of a natural origin) which increase the ability of an organism to adapt to environmental factors and to avoid damage from such factors."
Another definition requires that, for an herb to be considered an adaptogen, it must be nontoxic, nonspecific and have a normalizing effect on physiology.
By 1984, more than 1,500 pharmacological and clinical published studies had been conducted on adaptogens in the USSR, Adaptogens have even been described as "medicine[sic] for healthy people". In 1998, the term "adaptogen" was allowed as a functional claim for certain products by U.S. Food and Drug Administration and the European Medicines Agency claims, "The concept of adaptogens is sufficient to be considered in the assessment of traditional herbal medicinal products (e.g., monograph on Eleutheroccocus root)."
There is dispute in the herbal community regarding whether certain plants qualify as adaptogens. However, certain plants are generally believed to qualify:
- American Ginseng (Panax quinquefolius), root
- Ashwagandha (Withania somnifera), root
- Asian Ginseng (Panax ginseng), root
- Cordyceps (Cordyceps sinensis), mushroom/mycelium
- Dang Shen (Codonopsis pilosula, C. tangshen), root
- Eleuthero (Eleutherococcus senticosus), root/stem bark
- Guduchi (Tinospora cordifolia), root/stem
- Holy Basil (Ocimum sanctum, O. gratissimum), herb
- Jiaogulan (Gynostemma pentaphyllum), herb
- Licorice (Glycyrrhiza glabra, G. uralensis), root
- Reishi (Ganoderma ludicum), mushroom/mycelium
- Rhaponticum (Rhaponticum carthamoides), root
- Rhodiola (Rhodiola rosea), root
- Schisandra (Schisandra chinensis), fruit/seed
- Shilajit (Asphaltum bitumen), pitch 
Adaptogens in other cultures
The concept of adaptogens as "medicine for the healthy" or as a substance that helps the body cope with stress is a similar to many remedies common in chinese herbology, as well as other forms of traditional medicine.
Ayurveda traditional medicine operates with the concept of rasayana. Various substances are classified in this tradition as rasayanas, meaning they are believed to promote physical and mental health, improve defense mechanisms of the body and enhance longevity. Rasayanas are referred to as adaptogens by some researchers. 
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The mechanism of action of adaptogens is not entirely clear. In 1965, it was demonstrated that the adaptogenic effect was dependent on cellular transcription. Later, it was suggested that the action of adaptogens was at least in part a function of effects on the sympathetic nervous system.[clarification needed]
Another set of more recent of pharmacological studies have provided a mechanism for the effects at the molecular level. The stress-protective activity of adaptogens has been found to be associated with activation of molecular chaperonin Hsp70, and other key mediators of the stress response such as cortisol, nitric oxide, stress-activated protein kinase JNK and DAF-16. Studies have demonstrated that heat-shock factor 1 (HSF1) and Neuropeptide Y might be primary upstream molecular targets of adaptogens in neuroglia cells, but the results were only suggestive, not conclusive. One recent analysis revealed that a claimed adaptogen extract, ADAPT-232, and some of its components individually, regulated the transcription of genes involved in cellular signaling pathways, most notably those of G protein-coupled receptors.
Adaptogens vs. stimulants
|This section's factual accuracy is disputed. (June 2014)|
In spite of their theoretical normalizing effect, certain dosing regimens of adaptogenic plant extracts are claimed to have stimulating effects on the central nervous system. Plant adaptogens are said to stimulate the nervous system by mechanisms that are totally different from those of conventional stimulants as associated with metabolic regulation of various elements of the stress system.[clarification needed] Adaptogens are also claimed to be efficacious in the treatment of anxiety disorders.
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